Organics

Basil Trial for Basil Downy Mildew

19 August, 2019 by amygwh 4 Comments

A plant disease called Basil Downy Mildew has been yellowing basil leaves, stunting basil plants, and interfering with gardeners’ pesto dreams for many years. According to Cornell University, this basil disease was first identified in the USA in Florida in 2007. Since then, the disease has spread pretty much across the entire country, and beyond.

What is basil downy mildew?

Basil downy mildew is a plant disease that causes yellowing and browning of basil leaves. Because the first signs, the changes in color of the leaves, are also signs of other problems, like a lack of soil fertility, identifying downy mildew requires a closer look at the plant.

Sweet basil plant affected by basil downy mildew, August8
Sweet basil plant not yet affected by downy mildew, July 22

In the two plants above, the first shows leaves that are less brightly green. The tops of the leaves show some yellowing, and there are brown patches on the leaves, too. The undersides of its leaves are pale.

The other plant is actually the exact same plant, just a few weeks earlier in the summer. Back on July 22, the leaves were brightly green, un-mottled, and the backs of the leaves were also green.

To see if downy mildew is causing the change in the leaves, from brightly green to a mix of paler green with yellow and brown, turn a yellowed leaf over to look underneath.

If downy mildew is causing the problem, there will be purple-gray dots that are the spores of the disease that you can see if you look close. You might need a magnifying lens to see them well. From further away, the underside of an affected leaf looks almost silvered.

Backside of a basil leaf showing the purplish gray spores of basil downy mildew.

The good news for home gardeners is that not all basils are affected by the downy mildew. Finding resistant basils that have the flavor we desire is the next step in renewing our pesto dreams.

My home garden basil varieties trial

This year I planted eight kinds of basil. My goal was to identify hardy, good-flavored varieties for my yard. All but two varieties (‘Amazel’ and ‘Red Rubin’) were grown from seed that I bought from Strictly Medicinal Seeds.

The ‘Red Rubin’ seeds were from Nichol’s Garden Seeds. The ‘Amazel’ basil was a plant sent to me (for free) from Proven Winners.

The information below is what I’ve learned so far for each of the eight basil varieties currently growing in my yard (two are about to come out, because of the downy mildew).

Sweet Genovese basil (Ocimum basilicum)

Genovese basil has the “classic” basil flavor. It is the variety I have relied on for many years to fill my freezer with pesto, to be used in winter.

However, this is one of two varieties in my garden that currently are turning yellow and brown from downy mildew. The downy mildew pictures above are of this variety.

The good news is that I already harvested leaves from my two Genovese plants, early in July, to make pesto. That pesto is in the freezer now, waiting for its moment to shine in appropriate meals.

Sweet lettuce leaf basil (Ocimum basilicum)

Yellowed mottled leaves of basil plant in August — Lettuce leaf basil showing signs of downy mildew disease

Lettuce leaf basil is the other variety that is fading fast in my garden as a result of basil downy mildew. To be honest, this variety looks worse than the Genovese basil.

In the past, this has been a great basil to have in the garden, because the large leaves fit so nicely onto a sandwich.

If I had known what was coming to the plant this summer, I would have brought more of it into the kitchen before now.

Kivumbasi lime basil (Ocimum canum)

This is a new basil variety for me. I was curious about the flavor and wanted to know more. The great news is that the plant, so far, shows no signs of being affected by basil downy mildew.

Basil plant with flower spikes — Flower spikes of small-leaved Kivumbasi lime basil plant

The plant in my garden has small leaves, and the entire plant is not as large and robust-looking as some varieties. The flavor is the funny part. It really does taste like a mix of lime and basil.

I have not been super-successful in finding ways to use this basil in the kitchen. The description at Strictly Medicinal Seeds, where I purchased the seeds, suggests using the leaves in tea. Before I pull the plant from the garden, to make way for fall vegetables, I will harvest the remaining leaves to dry for herb tea.

The other way I’ve used the leaves is to make lime-basil popsicles. The result was a little odd, but you never really know until you try, right?

Mrihani basil (Ocimum basilicum)

Scallop edged green leaves of mrihani basil — Scallop-edged green leaves of Mrihani basil

This is another new basil for me, and it also shows no signs of basil downy mildew. The flavor is very good; it leans a bit toward anise. I am saving leaves for tea.

The leaves are large and scallop-edged. The scalloped edges are pretty in the garden, and the large size makes for an easy harvest. The plant is also large, for a basil.

The flower spikes start out green but mature to purple. Bees love them.

Thai basil (Ocimum basilicum)

Bumblebee on purple flower spike of a Thai basil plant — Purple flower spike of a Thai basil plant, with bumblebee

So far, I see no signs of basil downy mildew on this variety. The plants make tidy, globe-shaped mounds. The flower spikes are purple, which makes an ornamental contrast to the leaves. The basil flavor is spicy and good, but not exactly pesto-like.

If you order pho from a Thai restaurant, this is likely to be the basil that comes in the pile of green things that accompany your soup.

Greek basil (Ocimum minimum)

Small-leaved Greek basil, crowded by a cucumber vine.

This small-leaved variety also shows no signs of basil downy mildew. The plant is small all over, with a neat, tree-like shape if given proper spacing at planting time. My garden tended toward crowdedness this year, so my Greek basil did not develop the classic shape.

I have grown this basil before. The small leaf-size slows down harvest a little, but the strong, spicy flavor means a little bit goes a long way. The flavor leans toward cloves.

Red Rubin basil (Ocimum basilicum)

Purple leaves and purple flower spike of red rubin basil

This is the basil variety I grew last year, when I first decided to look into a wider range of basil varieties that might resist the basil downy mildew disease. Of all the non-Genovese varieties in the garden this year, this one has the most Genovese-like flavor.

Like last year, the plant does not show any signs of having basil downy mildew.

The leaves do shade toward purple. Both years that I’ve grown this variety, the plants have not grown to a large size. The leaves, though, are large enough that harvesting is easy.

‘Amazel’ sweet basil from Proven Winners (Ocimum basilicum)

Bright green leaves on basil plant — Downy mildew resistant ‘Amazel’ basil from Proven Winners

This plant was sent to me by Proven Winners, and it fit nicely into my plan to try more basil varieties this year. The plant shows no sign of basil downy mildew. The leaves are large-ish, brightly green, and the flavor is similar to that of ‘Red Rubin’ — not quite as sweet as the classic Sweet Genovese, but close.

Cornell University reports that the seeds of ‘Amazel’ are sterile, which means that, even if we manage to collect seeds from the plants, they won’t grow next year. However, many gardeners purchase herb plants, instead of seeds, for the garden each year. If they buy an ‘Amazel’, they will get a plant with good flavor that won’t suffer from basil downy mildew.

How to manage basil downy mildew in the organic home garden

Currently, no good treatment options exist for basil downy mildew in home gardens, even in gardens that are not managed organically. Commercial non-organic farms do have some chemical options, but even those are not perfectly effective.

Organic home gardeners should consider other strategies.

Change our expectations

Some of us may choose to branch out, flavor-wise, and bring some differently flavored pestos to the table. Certainly, there are many flavor options to try! Maybe a batch of lime-basil pesto would be less odd than my lime-basil popsicles. Maybe, too, I will eventually love lime-basil popsicles.

Plant resistant varieties

‘Amazel’ is not the only new Genovese-type basil variety that shows resistance to the downy mildew disease. A Basil Downy Mildew article from Wisconsin Cooperative Extension suggests ‘Eleanora’ as a resistant variety to try. Cornell University (linked earlier in this article) lists several additional varieties for home gardeners to try:

Devotion
Obsession
Passion
Thunderstruck
Prospera
Emma
Everleaf

Many of the above varieties can be purchased from Johnny’s Selected Seeds.

Change the timing of planting and harvest

Looking back at the first two pictures in the article, you can see that the plant on July 22 looked great. Evidence of disease did not show up until later. If I had planted more Sweet Genovese basil earlier in spring, I could have harvested loads of delicious basil leaves before August, with its heat and humidity that encourage downy mildew diseases.

Then, as the disease became noticeable, I could have removed them from the garden, replanting that space with another crop, knowing that I had plenty of pesto stored for use in later months.

Purchase steam-treated seeds

Some basil seeds are steam-treated to kill the basil downy mildew pathogen. The information might not be easy to find in a seed catalog or even online, but untreated seeds can spread the disease to your garden if they came from infected plants.

The disease can also come into your garden on the wind, which we can’t do anything about, but making sure our tools are clean, that plants we purchase to set into our gardens are healthy, and buying disease-free seeds are ways we can slow the spread of this disease.

Herb tea in my future

Glove-shaped Thai basil plant with green leaves and purple flower spikes — Globe-shaped Thai basil plant with green leaves and purple flower spikes, beloved by pollinators

Right now, my garden still contains several basil plants. They won’t all be there much longer, though. Soon, I will be harvesting leaves to dry (in my most excellent Excaliber dehydrator) for herb tea. Then, I will remove most of the plants to make room for planting vegetables that I want to grow for fall and winter harvests.

The Thai basil plants will stay in the garden until frost, to support the many pollinators that visit them every day.

Duct Tape for Pest Control

20 July, 2019 by amygwh

At the Plant-a-Row-for-the-Hungry garden where I volunteer, squash bug eggs have shown up on some of the squash plants. The eggs stick very tightly to the leaves, making them difficult to remove by hand. Duct tape, though, can help with egg removal.

Why are squash bugs “bad”?

Squash bugs aren’t essentially bad, but their activity on our plants can have a bad result. North Carolina State University’s Extension tells us that squash bugs suck the sap out of our squash plants.

Even if the plants don’t die directly as a result of this feeding activity, it can weaken them. The result is that they can make fewer squashes and become wilted. Neither of those outcomes is good. Getting rid of the eggs can slow the infestation down.

How to use tape to remove squash bug eggs from leaves

Cluster of tiny, shiny, bronze colored eggs on a green leaf. — Cluster of shiny, bronze colored squash bug eggs on a squash leaf.

First, identify the clusters of eggs.

What the eggs look like

Squash bug eggs are pretty distinctive. They are shiny, hard, bronze-colored, and appear in clusters on the leaves of squash plants. Sometimes, they are on the stems, too, but this is less common.

Why remove the eggs, rather than smash them where they are? These particular insect eggs are difficult to smash without damaging the leaves. Removing the eggs completely from the plant is the best hope for keeping the numbers of hatching eggs to a minimum.

Duct tape egg removal technique

Actually, the blue painters tape works, too, if you don’t have duct tape. It is likely that clear package-sealing tape would also work, but I haven’t tried it.

Bronze-colored bug eggs and hairy yellow larvae stuck to the sticky side of a piece of duct tape. — Duct tape can lift eggs and squishy larvae from leaves of your garden crops.

Just press the sticky side of a short section of tape to the squash bug eggs, then peel it away from the leaf. Most of the eggs will be stuck to the tape.

You may need to press a fresh section of the tape to the eggs a second time to get them all, but the tape works. With little effort on your part, the eggs will be gone from the leaves.

Now, of course, those shiny eggs are on the tape. When your piece of tape is “full”, fold it over and smash the eggs as well as you can, before putting the tape into a trash bin.

Duct tape can lift away other pests, too

You may have noticed that there are some yellow fuzzy things on the tape pictured above, along with the squash bug eggs. Those fuzzy things are the larvae (babies) of squash beetles.

Normally, I just smash those beetle larvae with my fingers, but I already had the tape in hand. Picking the larvae up with the tape was convenient, easy, and less icky than my usual method.

You can read about squash beetles and the damage they can inflict on your squash patch in my 2018 article about those particular pests. Older articles, from 2015 and 2012 confirm that this is not a new pest for my area.

Upbeat pictures, to end a “pest post”

After thinking about pests for awhile, it is good to switch over to thinking about more of the positive parts of gardening and being out of doors. These pictures might help:

Yellow swallowtail butterfly on large squash flower, that also has several bees working at the center.
Home garden vegetables from a recent morning’s harvest.
Frog on the table on our back deck.

Growing (and Eating) What’s Good for the Garden

7 April, 2019 by amygwh

New gardeners often are advised to grow foods that they and their families like to eat. It makes sense. Why grow tomatoes if no one at home will eat them? That advice, though, is less firm for gardeners who have been working their soil for a few years. Longer-term gardeners should consider branching out a bit, with regard to what they grow. Here is why:

Different crops can improve your crop rotations

Crop rotation is the practice of growing different kinds of crops in succession within a growing space. “Different kinds” here means plants from different plant families. An example of crop rotation, to illustrate the practice from one space in my garden, is this: kale (fall/winter), followed by peppers (summer), followed by garlic (fall/winter).

Why should you be concerned about your crop rotations?

Bowl filled with shelled cowpeas surrounded by garden vegetables including okra, tomatoes, and peppers. — Cowpeas, in the bean family, help diversify my crops in summer.

University of North Carolina’s article, Advantages of Crop Rotation, explains that rotating crops can reduce buildup of pests and diseases. It can also improve the balance of nutrients in the soil and improve soil structure.

Organic gardeners, especially, who may see themselves as stewards of the soil, will find that crop rotation is a practice that can enhance their gardens.

A chef argues for eating more kinds of crops

I remember reading a Yale Environment 360 interview with chef Dan Barber who explained how he came to understand that supporting sustainable agriculture can mean learning to eat new crops.

The central example discussed in the interview was a farm that was growing emmer wheat, an ancient variety that Barber was excited about using in recipes. This is the relevant bit in the interview:

…I was standing in the middle of a field, and all of a sudden discovered that he [the farmer] was growing very little wheat, and that instead he was growing a whole suite of lowly grains like millet and buckwheat and barley, and leguminous crops like Austrian winter peas and kidney beans. He was growing a lot of cover crops like vetch and clover. And they were all meticulously timed and spread out among the 2,000 acres I was standing in the middle of. And that’s when I sort of had this agricultural epiphany. But it led to this gastronomic epiphany, which was that here I was as a farm-to-table chef waving the flag of sustainability and realizing that I wasn’t supporting most of the farm. In the case of Klass [the farmer growing the emmer wheat], he needed these lowly crops and cover crops and leguminous crops because his soil health needed it to grow wheat. You couldn’t get the wheat unless you grew all these other crops. And you had to time it in this way that brought the fertility to the soil to give you this incredible tasting wheat.
Diane Toomey, How to Make Farm-to-Table a Truly Sustainable Movement, interview with chef Dan Barber, Yale Environment 360, 15 Sept. 2014

Most of us are not going to develop elaborate rotations for the production of emmer wheat, but the interview made me feel like less of a loon for growing – and learning to prepare and eat – crops that are not my favorites, all because I thought they’d be good for the garden.

Adding more plant families to the rotation, for home gardens

An example of adding beets

Red beet with red-veined green leaves growing in soil. — Garden beet in April.

Years ago, I decided to expand my spinach/amaranth family plantings by growing beets, even though I didn’t really like beets. I could have planted more spinach, instead, but the phosphorus level in my soil was a little high. I knew that a root crop like beets would use up some of that extra phosphorus, helping to rebalance the nutrients in my garden’s soil.

Over time, as a result of this decision, I learned how to prepare beets in a way that Joe and I actually like. Now, beets are just one more good food that we look forward to bringing in from the garden.

I have worked on collard greens in the same way, but with less success. The good news is that Joe likes them.

Why grow collard greens?

A good reason to grow collard greens is that collards (and mustards) help suppress the root-knot nematodes that are such a big problem in Southern soils. At the garden/farm where I used to volunteer, the winter mixed-greens crop of collards, mustards, kale, and radishes was called a “fumigant” crop for the good work it does in cleaning up the ever-present nematode pests in the soil.

These greens can stay in the ground all winter long in the South, harvested leaf by leaf, so they work on the soil for many months. Tilling in the remaining leaves and roots about a month before spring planting just frosts the cake of their beneficial effects.

Plant families for garden crops

The list of plant families that include food crops, to enhance your own garden crop rotations, is large. Here are examples of plant families and some crops in each one:

Tomato family – tomato, pepper, eggplant, potato, tomatillo
Cabbage family – cabbage, broccoli, kale, collards, mustards, radish, turnip, kohlrabi, Brussels sprouts, cauliflower, arugula/rocket
Bean family – bush beans, pole beans, Lima beans, peas, Southern peas, cover crops like clover and vetch
Onion family – onions, garlic, shallots, chives
Carrot family – carrots, parsley, cilantro, parsnips, dill, fennel
Spinach family – spinach, Swiss chard, amaranth, beets, Good King Henry
Squash family – cucumbers, summer squashes, zucchini, winter squashes, pumpkins, melons
Sunflower family – sunflowers, lettuce, chicory, radicchio, escarole, endive
Mallow family – okra, roselle
Morning glory family – sweet potatoes
Mint family – mint, basil, oregano, thyme, anise hyssop, rosemary, sage, marjoram
Borage family – borage
Grass family – corn, wheat, rice, oats, lemongrass
Buckwheat family – buckwheat, French sorrel (and rhubarb, which is not a plant for the South)

Growing some chicories

Pale green lettuces and dark red radicchio plants growing together in a garden bed. — Radicchio (right) is a kind of chicory, which is in the same plant family as lettuces (left). Growing them together makes crop rotation simpler.

Personally, I would like to see more gardeners branching out a bit into the unknown, in terms of crops. That is why I took seedling chicories to the Soil3 Garden Show, to give away with a handout of information about chicories.

I have found that these plants are relatively pest-free in our area. For organic gardeners in the South, pest-free crops are an amazing gift! Chicories also have deep roots, which can help break up heavy soils and can bring up nutrients from deeper soil layers.

Clump of 'Italiko rosso' chicory - upright leaves are dentate and have red veins. — ‘Italiko Rosso’ chicory in the fall, ready for harvest to use in salads or on pizza.

In addition, they are useful in the kitchen as greens, which we all probably need to eat more of (chop some up to put on your pizza), and the roots can be roasted to make a coffee substitute. If the plants stay in the garden over a winter, they will produce a tall stem with blue flowers, in spring or early summer, that will support many pollinators.

Not everyone will appreciate the bitter flavor of chicories, but if you like the flavor of radicchio in your salads, you may like other garden chicories, too. The very first one I grew, Italiko rosso (which Baker Creek labels as a dandelion, possibly because of its leaf shape), is still a favorite.

Hope your gardens are all growing well!

(If this blog post is interesting or useful to you, please “like” or “share” it. Thank you!)

Planting Dates for Summer Garden Vegetables

18 March, 2019 by amygwh

As spring advances and weather warms, the urge to plant the summer garden becomes almost overwhelming. Knowing which crops can stand a bit of cooler weather and cooler soil can help us make good choices about what to plant when we just can’t wait any longer.

Understanding the last frost date

Most of the garden vegetables that we grow in summer are frost tender, which means that they won’t survive freezing weather. This is why most seed packets use the “last frost date” — the expected date of the last freezing temperatures — as a marker for when to plant summer crops.

Where I live, the average date of the last frost in spring is in mid-April. The date is not exact; we estimate the date based on the dates of the last frost in previous years. Annoyingly, we won’t know the exact date of the last frost for this year until we are well past it. Some years, the last frost in my yard is in March, and one year my yard had a frost on April 23rd.

The role of soil temperature

Cucumber seedling with three true leaves, already planted in the organic home garden. — Cucumber seedling transplanted into the garden in April.

Part of finding the best time to plant vegetables is knowing the best temperature for seeds to sprout and for plants to grow. Texas AgriLife Extension points out that these two temperatures are not necessarily the same. For example, bean seeds may sprout best at a soil temperature of 85 degrees F, but that temperature isn’t best for plant growth and productivity.

The AgriLife article lists reasonable, “compromise” soil temperatures for planting many crops:

cucumber (64°F)
cantaloupe (68°F)
okra (73°F)
pumpkin (75°F)
squash (70°F)
watermelon (72°F)
beans (72°F)
beets (45°F)
tomato (55°F)
turnip (50°F)
corn (55°F)

From the list, you can see that beets and turnips (cool-season crops) can do well in cooler soil, corn and tomato plants slightly warmer, and cucumbers and cantaloups a bit warmer still. This information can help in planning your schedule.

Recommended date ranges from University Extension programs

UGA publishes a Vegetable Planting Chart that shows suggested planting dates for garden vegetables. The dates are for middle-Georgia (a line through Macon across the state), which means that the dates need to be adjusted for areas north and south of that line.

Tomato transplants for the organic home garden, indoors under lights on a cold day.

For my area, just north of Atlanta, I would add about two weeks to the ranges in the UGA planting chart to get a reasonable planting date range for my garden.

North Carolina State University Extension publishes a planting chart for Western North Carolina. The dates are similar to those that I would use for my garden.

You may notice that the recommended date-ranges in the linked publications for spring planting can be quite large – up to six weeks for some vegetables. The whole range of dates might be good theoretically for a particular crop; however, for organic home gardens, there are some good reasons for choosing to plant either at the early end of the range or the late end.

Reasons to consider dates at the edges of the recommended ranges

For both bush beans and pole beans, I usually plant as early as I think the plants can survive the experience. The early planting — as early as the first week in April, if the weather forecast looks ok — means that I start harvesting beans before the end of May. By the time the Mexican bean beetles show up to demolish the plants, I will have harvested plenty of beans.

I also choose an early planting date for cucumbers, squashes, and melons. Those plants all are attacked by mildew diseases in late summer and an assortment of pest insects in mid to late summer. Early planting allows a larger harvest, before the plants are affected by whichever problem attacks first. For these crops, planting seeds in the first week in April, or transplants a week or two later (when the soil is warmer), can make a big difference in how much food I can harvest before the plants die.

Okra and sweet potatoes are two crops that I plant at the later end of the recommended planting date range. Both of those two crops grow slowly in cool weather, and I have found that keeping ahead of the weeds, which grow faster, is more work when these two crops are planted early. When okra and sweet potatoes are planted later, in early or mid May in my yard, they grow fast enough to shade the ground sooner, and weeds have less chance to take hold.

Tomatoes are another crop that I plant later than almost every other gardener I know. My experience is that later-planted tomatoes, like at the end of April or early May, are less troubled by blossom-end rot than earlier-planted tomatoes. They also are more likely to survive whichever soil-borne wilt disease is in my yard, and infection by the ever-present early blight disease is usually less severe.

Organic gardeners won’t use the chemicals that are available in garden centers to control all the above problems. Instead, we have be a bit wily about getting around the diseases and pests that can reduce the productivity of our organic home gardens. I have found that adjusting my planting dates to the edges of the date ranges, for some crops, is all the “control” I need.

Of course, keeping a good attitude about the vagaries of the natural world also helps.

Amy’s planting schedule

In case you are curious, this is when I plant the standard summer crops, most years, in my garden, zone 7B, just northwest of Atlanta:

first week in April – plant seeds for bush beans and pole beans if forecast is ok; if a freeze is in the forecast, I start these in a flat or tray, to transplant to the garden after a couple of weeks. I also start squash-family plants – cucumbers, zucchini, winter squashes, melons – in little pots this week, to transplant to the garden when the soil is warmer.
mid-April – plant corn, if any is planned. For me, that is usually popcorn. Early planting for corn reduces problems with corn ear-worm. Later plantings almost always have more ear-worms. Plant the transplants (beans, squash family plants) when the first true leaf is a couple of inches across.
late-April – plant pepper plants, and seeds for Swiss chard (if planned).
early May – plant tomato and eggplant transplants, seeds for okra.
mid-May – plant sweet potato slips.
mid-summer – plant Southern peas when one of the earlier crops comes out of the garden (bush beans or cucumbers are usually the first to go). After bush beans have been gone from the garden for a couple of weeks, if there aren’t any pole beans also in the garden to harbor more Mexican bean beetles, plant a new patch of bush beans.

What the above schedule doesn’t show is that I start tomato and pepper plants from seed, indoors, in early March. It also doesn’t include annual herbs, like basil or borage, or flowers, like nasturtium and Zebrina hollyhock, that I plant most years.

Protecting early-planted crops from frost

The summer crops are frost-tender, but I plant some of these crops early enough that the risk of frost is high. A couple of different strategies can be used to protect your crops.

The first strategy is the use of transplants to allow an early start for some crops, like beans and cucumbers. This strategy takes some planning, and it takes space in your house. It also, though, protects plants from cooler weather, since they are indoors. The plants can be planted into the garden when the risk of frost is lower.

The second strategy is the use of row covers to protect tender crops in the garden from a light frost. If a hard freeze happens and the row cover does not fully protect a crop, some replanting might need to be done. The good news here is that most seed packets contain enough seeds to replant a small home garden.

For further reading, my older post about planting seeds in the garden contains reminders about planting depth and plant spacing that might be helpful.

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Broccoli, Beets, and Boron – Updated

8 March, 2019 by amygwh

Soils in the region where I live are short on the mineral boron, an essential plant micronutrient. The University of Georgia soil lab doesn’t measure boron levels in its routine test for garden soil, but it does include a recommendation to add some to a home vegetable garden. This is the recommendation:

“Apply 1 tablespoon of borax per 100 feet of row to broccoli and root crops such as turnips and beets. This can be applied by mixing the borax thoroughly with approximately 1 quart of soil in a container and then applying the mixture along the row; or it can be mixed with a quart of water and applied to the soil in solution.”
University of Georgia, Soil Test Report, basic soil test for Home Vegetable Garden, 2018

What is a micronutrient?

The micronutrients are needed in tiny amounts, but they are essential for plant growth. Boron is one of several micronutrients that plants need. Other micronutrients include copper, iron, and nickel, among others.

For boron, the difference between not-enough and too-much is a pretty narrow range, according to K. Kelling at the University of Wisconsin and Ron Goldy at Michigan State Univ. Extension. This means that great care must be taken to not use too much.

How does boron help plants?

Golden beets growing in the garden - beets are a crop that need a little more boron than others. — Golden beets growing in the garden – beets are a crop that need a little more boron than others.

UMass Extension, Amherst, says that boron “is required for many different aspects of plant cell functioning, including protein synthesis, development of cell walls, carbohydrate metabolism and sugar transport, pollen growth, fruit set, and seed production.”

Sounds important, to me!

What happens when plants don’t get enough boron?

The UMass information about boron deficiency lists these possible effects of too-little boron:

“stunting and distortion of the growing tip”
“brittle foliage and yellowing of lower leaf tips”
reduced flowering
reduced fruiting
distorted fruit
“brown heart” (mushy brown centers) in root crops like turnips and rutabagas
hollow stems in broccoli and cauliflower
brown or otherwise discolored curds on cauliflower

Kelling’s Soil and Applied Boron publication adds that cabbages that are low on boron may show an “internal breakdown of head”.

Which plants need the most boron?

Some vegetable crops need more boron than others.

Broccoli growing in the organic home garden.

Ron Goldy’s U Michigan publication lists crops and their relative need for boron. The high-need vegetables for boron he includes are these:

broccoli
cauliflower
celery
table beets
turnips

How can I provide boron to my garden?

One way to add boron is to follow the instructions on the UGA soil test report, to mix a tablespoon of borax in water or with soil and to spread that across a 100-foot row of garden, especially in areas where higher-need vegetables are growing. If your garden is not in rows, or is smaller, it will need less borax.

The borax you will need is in the laundry section of your grocery store, in the box of 20 Mule Team Borax. This should be fine for organic gardens, because it is a mined mineral.

You will need to be careful with this product, though, because it is easy to use too much. Do not apply the boron every year without having the boron levels tested at a reliable soil lab.

If you prefer to use another product, one that contains many micronutrients, including boron, to safely fill any gaps, try kelp meal. It is much more difficult to use too much boron when using kelp meal, because it is a much less concentrated source of the micronutrient. There is enough, though, to help your plants. Just follow package directions for safe use in your organic home garden.

Georgia isn’t the only state with low-boron soils

The 20 Mule Team Borax company notes that boron will be at low levels in soils that are sandy, or acidic, or that are low in organic matter (like Georgia clay!), or that are in areas of high humidity.

The company has found that low-boron levels are a common problem in soils east of the Rockies and in the Pacific Northwest. The middle of the country and the Southwestern region mostly have sufficient boron.

To learn more about soil fertility in organic home gardens, read my posts about potassium sources, soil pH, building good garden soil, and side-dressing your garden crops.

GGIA Trade Show Notes for Organic Gardeners

29 January, 2019 by amygwh

The trade show at this year’s WinterGreen conference of the Georgia Green Industry Association (GGIA) provided a look at some new (and not so new) products and plants for organic gardeners. The event was held last week, in Duluth, GA.

Most vendors at the trade show specialized in ornamental (non-edible) plants, machinery for large operations, products for commercial nurseries, and chemical-companies, but I located some local/sustainable/organic-related vendors, to share with you.

Recycled plastic nursery pots

East Jordan Plastics, in Michigan, displayed planting trays, growing pots, and some larger containers made from recycled plastics. Many gardeners are concerned about the excessive use of plastics in gardening. It is good to know of a plant-product company that is working to cut back on plastic waste, by re-using containers and recycling other plastics to create new containers.

RootMaker pots

Image from the RootMaker catalog showing difference in root growth between sprout in regular pot versus sprout in RootMaker pot. — Image from RootMaker catalog.

RootMaker trays and pots for growing plants are the result of research in container design, with the goal of more robust root systems. The trays and containers that I examined seemed very sturdy — like they would last for years — and the informational literature was very compelling. The pots and trays have an unusual pattern of protrusions and holes inside, and those, according to the information, guide root growth into more-branched root systems.

I will be trying a RootMaker tray this year. The representative at the Trade Show did give me a couple of fabric liners, for use when growing plants in cinderblocks, so I cannot say that I am 100% unbiased. I will have to buy the tray, though.

Rice hulls for mulch

Until this trade show, I had not heard of using rice hulls as mulch in containers or as a substitute for perlite in planting mixes.

PBH brought samples of parboiled rice hulls, so people could see the actual product and understand how it can be used. The rice hulls are approved for use in organic systems. I did not bring home a little baggie of rice hulls, but I could have. There were plenty on the table. I did bring home the informational literature, to learn more.

Rice hulls pictured on the cover of an article titled "Rice Hulls 101".

PBH Nature’s Media Amendment is from Riceland Foods. This shouldn’t have been a surprise, but it was. It makes sense that the rice industry would want to find a good use for this bi-product of rice production. Looks like they were successful.

Pope’s CBD oil

This isn’t organic and it isn’t about growing, but I did learn that Tennessee grows industrial hemp. The CBD oil was displayed in what was otherwise an all-succulent-plants booth, for Pope’s Plant Farm. CBD oil seems to be a popular product these days. If anyone was looking for a local (-ish) source of CBD oil, Pope’s Plant Farm is one place to try.

Display for Pope's Plant Farm at the 2019 GGIA Wintergreen Conference.

The little succulent plants in the Pope’s booth were very cute. If I were more of an indoor gardener, I would probably grow some. My oldest son in Colorado does grow little succulent plants, so I pay more attention to them than I used to.

Bottom’s Nursery for fruit trees and other plants

Its plants are not organically grown, but after they are planted, most of the varieties at Bottoms Nursery will not need intensive programs of chemical sprays. All the varieties I saw in the catalog are relatively easy-care fruits that would do well when switched to organic management after planting, even in the South. Some are varieties that would do well in small space gardens.

Front cover of the 2019 catalog for Bottoms Nursery, which is in Concord, GA.

The fruit trees at the back of the booth are what attracted my attention. The first tagged tree I noticed was a Kieffer pear, which I know to be both hardy and a producer of good-tasting fruit.

I wasn’t the only person drawn to the booth of Bottoms Nursery. Another vendor was there, discussing trees and other plants to order, to sell in his General Supply store.

General Supply, Inc, in Blairseville, GA

General Supply is the kind of “everything” store that makes some gardeners go into raptures. This is the store mentioned above that will be selling plants from Bottoms Nursery, but it is also a source of tools, pet supplies, small farm supplies, and a million more interesting things.

Hand tools display in General Supply booth at GGIA 2019 Wintergreen Conference.

Of course, hand-tools are pretty appealing for gardeners working in small space gardens. We don’t need a large assortment of full-sized equipment for our little plots, but good tools make the work easier.

I was especially interested in the Truper brand tools (long-reach 15″ length, ash wood handles, sturdy forged “business ends”), but a full line of Corona tools — which are long-lasting and easy to use — was also on display.

The guy at the booth (so sorry that I did not record his name!) and I discussed the ergonomic benefit of tools that have the “business end” at a right-angle to the handle, when he showed me another tool designed for easier use.

The pruner on the right, in the nearby image of two Corona-brand pruners, has a different angle for the cutting edges. Do you see the difference? According to the guy in the booth, the angled pruner on the right would be easier to use on some branches, because it allows your arm and wrist to stay aligned, rather than to bend.

I haven’t tried it, so I don’t whether that really works, but I would be interested to try. When late-winter pruning time comes around (soon!), it would be good to avoid aggravating old injuries.

Gardeners heading toward the Blairesville area might want to put this store on their list of places-to-visit.

What else happens at the GGIA WinterGreen conference?

In addition to the trade show, the event provides continuing education opportunities for commercial lawn and garden folks. I did attend a workshop about Beneficial Insects, but that story is for another post.

Soil pH and Garden Success

15 December, 2018 by amygwh

When a garden hasn’t been doing well, one of the first conditions to check is the soil’s pH, its acid-alkaline balance. The pH scale goes from 0 to 14; 7 is the neutral pH, measurements below 7 are acidic, and measurements above 7 are alkaline.

For reference, distilled salad vinegar has a pH in the range of 2 to 2.5 (acidic), and cold-process soap has a pH in the range of 9 to 10 (alkaline).

Soil pH influences how well plants can take in nutrients from the soil, so getting a garden’s soil into the best pH range for your plants will help them be healthier and more productive.

What is less well-known is that correcting a pH that is either too high or too low takes time. Testing soil pH should be done now, or soon, for gardens that have not done well in the past year.

What pH is good for gardens?

Blueberries will be ripe beginning in mid-to-late June. — Blueberry plants prefer a soil pH near 5.

Most garden veggies need a soil pH of between 6 and 7. Where I live, northwest of Atlanta, the natural soil pH is lower than that range — it is naturally acidic. With that acidity in mind, many people here routinely add lime to their lawns and gardens without checking the soil pH first, and end up with a soil pH that is too high.

When I worked at the local Extension office and managed the soil samples that went to the soil lab at University of Georgia (UGA), it was not unusual to see some samples with soil pH around 5, but others with pH higher than 8. Those higher pH soil samples were from lawns and gardens that had been limed pretty much every year.

Once, a friend who decided to plant blueberries in the space where she had originally kept a vegetable garden sent a soil sample in to the lab at UGA. The lab found that the pH of her soil was 7. This pH level was not a surprise because she had been spreading ashes from her fireplace on the garden. Wood ashes are a good source of potassium, but they raise the soil pH.

For many veggies, a soil pH of 7 is fine, but the blueberries she hoped to plant in that space prefer a pH closer to 5. That soil needed some work before it would make a good home for blueberries.

How can I find the pH of my garden soil?

Example of easy to use soil pH test kit for home gardeners.

The most reliable method of finding your garden’s soil pH is to send a soil sample to your state’s soil lab. Call your local county Cooperative Extension office to find out how to take a representative soil sample, how to package it, and the lab fee for this service.

Another option is to purchase a pH test kit at a local garden center. One I have used (pictured nearby) includes a container with color chart for comparison, capsules of pH-indicator-powder to add to the container, and instructions.

The basic instructions for this kit, and others:

put a tiny bit of garden soil into the container
add the indicator powder
add water up to a line near the top
put the lid back on the container, then
mix the parts together by shaking the container until color develops.

You find the pH by comparing the color of your sample to the chart on the front of the container.

Soil sample in pH test kit with water and indicator powder, to read the soil pH. — Sample in pH test kit shows pH of soil in my upper flower bed to be about 6.5.

How to lower a too-high soil pH

The UGA soil lab sent information to my friend about how much aluminum sulfate (the cheapest option) to add in order to bring the pH down to a better level for blueberries. If you know that the pH of your garden soil is too high, but don’t have a lab-recommendation for how to lower it, the amount of elemental sulfur (my preferred option) needed can also be found in a table by Clemson University Extension, in its Changing the pH of your soil publication.

For a soil pH that is only slightly high (about 0.5 higher than the desired level for your plants), one of my county’s former Extension agents used to recommend mixing sphagnum peat into the soil as a quick fix. Iowa State University Extension suggests other amendments that can lower a too-high pH, including “elemental sulfur, aluminum sulfate, iron sulfate, acidifying nitrogen, and organic mulches.”

There is a note, too, that a very high pH (over 8) is hard to bring down. When the local Plant-a-Row-for-the-Hungry garden (one of my volunteer groups/projects) was at a location that had a high-pH soil, we added the recommended amount of sulfur several years in a row before the pH started to come down.

How to raise a too-low soil pH

The Iowa State University publication How to change your soil’s pH includes a table showing how much ground limestone will be needed to raise soil pH. If you have hydrated lime handy, and think it might be a “quicker fix” for a too-low pH, please don’t try it. The risk of raising the pH too high with this product, by accident, is large. Lowering the pH after over-liming is difficult and can take a long time. Use ground limestone instead of quick lime or hydrated lime.

It takes more lime to raise pH in a clay soil than in a sandy soil. In general, according to the table in the Iowa State publication, for 100 square feet of clay-soil garden, it takes 5 to 6 pounds of limestone mixed into the top six inches of soil to raise the pH by 0.5.

When is the best time to adjust the soil pH?

For my friend’s blueberries, the UGA lab report recommended that the bushes shouldn’t be planted until 6 months after applying the sulfur. If she added the sulfur in October, that means blueberry-planting should — for best effect — wait until April. That is pushing the boundary for good planting time for woody plants like blueberries; as spring progresses and the weather warms, newly planted bushes are less likely to do well. They need time in the soil for their root systems to become established before being stressed by the heat of a Georgia summer.

What this means is that soil testing should be done now, if it hasn’t already been done, so adjustments to pH can be made soon enough to benefit plants that will be planted in spring.

What soil pH is best for my plants?

An article by Lewis Hill, published in Robert Rodale’s The Best Gardening Ideas I Know (1983) includes a list of some garden plants and the pH ranges they prefer. I’ve pulled some of the food plants from his list to post here:

pH 4 to 5: blueberry
pH 5 to 5.75: blackberry, grape, parsnip, plum, potato, pumpkin
pH 5.75 to 6.5: bean, citrus fruits, cowpeas, currants, gooseberry, oats, pepper, rutabaga, rye, squash, strawberry, tomato, turnip
pH 6.5 to 7: apple, beet, broccoli, buckwheat, butternut, chicory, chives, cucumber, eggplant, endive, kale, leek, muskmelon, onion, pea, peach, radish, raspberry, rhubarb, spinach, watermelon, wheat
pH 7 to 7.5: alfalfa, asparagus, barley, cabbage, carrot, cauliflower, celery, lettuce, nasturtium, parsley

This list may help other gardeners in planning what to plant where, but it is comforting to remember that plants will still grow and produce in soil that is slightly outside their preferred pH range.

This is lucky, since most of us grow many of these plants mixed all together in our gardens. However, for peak production, planting in soil that is actually the preferred pH for each crop works best.

Succession planting with preferred pH for each crop in mind

When I plant Irish-type potatoes in the spring, I will have added some sphagnum peat to their soil to bring the pH down a bit, but not all the way down to 5. Knowing the pH preferences of other crops helps me know what to plant after the potatoes in that space. For example, cabbages in that space would likely be a total bust, because their pH preference is so much higher (7 to 7.5!).

After potatoes are harvested, a better option than cabbages would be to let a nearby vining crop, like melons, sprawl across that space. Another option would be to plant a crop there that prefers a lower pH range, like beans or cowpeas that thrive at pH 5.75-6.5.

(If this information seems helpful or interesting, please remember to “like” or “share” it. Thank you!)

Something is Making Holes in My Squash Flowers and Stems

11 September, 2018 by amygwh

Over the past couple of days, I have noticed that several flower buds on my zucchini squash plants don’t look healthy. The flower buds have stayed small and turned pale and droopy. Today, I finally took the time to REALLY inspect my plants. What I saw is a lot of bad news.

The holes in the flower buds and the holes in the stems could — possibly — be caused by several kinds of insects. However, the piles of pale green, round globs like tapioca, and the yellow globs too, are most likely frass (poo) from caterpillars.

Around here, a major cause of this kind of damage is squash vine borers. The adult moths lay eggs on the plants. Then, the tiny caterpillars that hatch out of the eggs eat their way inside the plant, where they eat and eat until they have killed the plant from the inside.

I pulled up two of my five zucchini plants to try to find the culprits/caterpillars. As I dissected the plants, this is what I found:

What are pickleworms?

Pickleworms, the caterpillars of a night-flying moth, are a common summertime pest in the South. They are pests I have seen before, but I have not seen such extensive damage to plants from their activity before. Who knew that they would gnaw right into a stem? Not me. At least, not until now.

If the damage had been from squash vine borers, I would have pulled up all five of the zucchini plants and called them an interesting late-summer experiment that I never need to repeat. Since the damage is from pickleworms, I am trying another option. That second option is the use of an organic-approved product for caterpillars.

Organic control for pickleworms

I have mixed up some “Bt for caterpillars” – the product at my house is Thuricide, but others are available – and I’ve sprayed it all over the stems and flower buds of the remaining zucchini plants and my little patch of cucumbers. The name “pickleworm”, if you haven’t already guessed, alludes to a fondness for cucumbers. Since I like cucumbers, too, it would be nice to bring any cucumbers that these plants make into my kitchen, without caterpillars inside.

I planted seeds for cucumbers the same day I planted the zucchini. With a time-to-maturity of 65 days, they seemed less likely than the zucchini to make a crop before the first frost, but they are another late-summer garden experiment. Since they have plenty of flowers on them, the odds look good that I might harvest a couple of cucumbers before the end of October.

This hope for cucumbers depends on me and the Bt. It will need to be re-applied every week, and after every rain, for the Bt to work well.

Wish me luck?

Beneficial Garden Insects: Flower Flies

31 July, 2018 by amygwh

While I’ve been walking outside our little town in Italy, missing my vegetable garden, I have paid attention to the local plants. On good days, I see a lot of flowers and pollinator-insects. At first, I thought the pollinators were all bees. Then, I looked closer. Many of them are actually flower flies, a different group of beneficial garden insects.

Flower flies, which are beneficial garden insects, look like bees but without the sting. — Flower flies are beneficial garden insects.

What are flower flies?

Flower flies really are flies, but a lot of them look like bees. It is possible that looking like a bee prevents some predators from eating them. I don’t know if that mimicry really works, though. We used to have a dog that ate carpenter bees when she could catch them. The stinging inside her mouth didn’t seem to stop her from catching and eating more.

Flower flies do not sting or bite, but they do eat nectar and/or pollen as adults. As they visit flowers to gather food, they pollinate the flowers. Flower fly babies (larvae) eat aphids and other small insects. These are definitely beneficial garden insects!

Organic gardens, in particular, rely on pollinators and predators in the garden to increase harvests and reduce pest problems. We can wait for our helpful predators (like flower flies, wasps and ladybugs) to eat the aphids, no spraying required!

Flower flies are also known as syrphid flies and as hover flies.

How can I tell which is a flower fly and which is a bee?

With only a brief glance, it is not easy to tell bees and flower flies apart. If you have the fortitude (and lack of bee-allergies) that allows you to look a little longer, you might see the difference.

Check the antennae

Flower flies have short, straight, stubby antennae. The antennae may be so short that they are hard to see. Bees have longer antennae, and their antennae are more likely to bend.

Check the wings

All flies have only two wings (one pair), and you can easily see them. One wing is on each side of the body.

Bees have fours wings (two pairs). The larger front pair of wings is easy to see, but the hind-wings can be hidden below the front pair. You might not be able to see that there are four wings.

Check the eyes

Eyes of flower flies are larger, and more on the front of their heads. Bee eyes are shifted a little to the sides of their heads.

Check the back legs

Flies do not collect pollen in clumps on their back legs. Some kinds of bees, especially our native, solitary bees, also do not collect and carry pollen on their back legs.

However, bumble bees and honeybees often store clumps of pollen on their back legs, to carry back to their colonies. If you see a bee-like insect that has pads of orange, or red, or yellow on its back legs, that is a good sign that the insect is some kind of bumble bee or a honeybee.

How can I attract flower flies to my garden?

University of California has published an easy-to-use table of plants that attract flower flies (see page 16). The table is deep within a document that is not super-easy to read, and not all the plants will grow well in the Southeastern US, but many will.

Here is a short list of plants that are known to attract and/or support flower flies to your organic garden, that I know will grow in the Southeastern US:

buckwheat, coriander/cilantro, thyme, Italian oregano, sweet alyssum, fennel, tansy, white-flowered yarrow

Side-Dress Your Vegetable Garden if Needed

2 July, 2018 by amygwh

If plant growth in your garden has slowed, or your plants are looking puny, it might be time to side-dress your vegetable garden with fertilizer. What does that mean? Side dressing is applying additional fertilizer near your crop plants, either spread on the ground around them or in a little furrow a few inches away.

Side-dressing helps some crops more than others

Some crops will not need additional fertilizer in mid-summer to make a full harvest. These, mostly, are the beans and peas — Southern peas especially, like purple hull peas and zipper creams. Most of the other fruiting crops in a summer garden, like tomatoes, peppers, cucumbers, corn, eggplants, and squashes, may benefit from additional fertilizer. These crops are often referred to as medium feeders or heavy feeders. They have a higher need for some nutrients.

Side dress your vegetable garden tomatoes in mid-summer, if needed. PHOTO/Amygwh

For plants that benefit from additional fertilizer in mid-summer, it usually is applied either when plants have begun to set their fruit (squash and cucumbers count as fruit, since they have seeds), or, for corn, when it is “knee high.” If your crops are further along than this, it is not too late to side-dress, if plant growth or productivity seems slow.

How to know if you need to side-dress your vegetable garden

These gardens are most likely to benefit from mid-summer side-dressing with fertilizer:

Gardens with sandy or fast-draining soil
Gardens that have received more than the usual amount of rain
Gardens fertilized with water-soluble, conventional, chemical fertilizers
Gardens that support a lot of medium and heavy feeders

In the first three examples, some of the nutrients added in spring may have washed away, out of reach of the plant roots. When nutrients are out of reach, plant growth will slow down, some plants may start to look a little pale, and harvests will not be as large as they should.

If the only plants in your garden that look pale/puny by mid-summer are the tomatoes, peppers, and/or eggplants, and all other crops are growing well, these crops might need a little extra magnesium. In my county, soils are low on magnesium. The tomato-family plants all have a slightly higher need for magnesium than other crops. This combination can result in plants that are pale and less productive.

To boost the available magnesium for these plants, use epsom salts. Dissolve a couple of tablespoons of epsom salts in two gallons of water, and pour it on the ground around your plants. Two tablespoons-full dissolved in two gallons of water should be enough for four plants. If the plants start to look darker green in about a week, then they needed the magnesium.

You also, of course, could get your soil tested through your local County Extension office. A soil lab report will tell you whether any nutrients are in short supply and offer a fertilizer recommendation. Extension fertilizer recommendations are, at this point, still all for conventional, chemical fertilizers, but even this can be helpful in pointing out the needs of your garden’s soil.

Some gardens may not need side-dressing

Gardens with soil that is, essentially, all compost
Gardens that are 100% beans and Southern peas that have been inoculated with bacteria that help fix nitrogen

If your garden soil is all-compost in a raised bed, and the compost was all new this spring, then the odds are good that your plants will not need side-dressing. Some community gardens in my county fill new beds with a product called “Soil3”, from SuperSod. This is an all-compost product. Soil3 and similar composts available in other areas can provide all the nutrients the garden plants will need for the first summer. Organic fertilizers may be needed in increasing amounts in later years.

Which organic fertilizer is good for side-dressing?

The vegetable garden fertilizer you already have
Fish emulsion or a seed-meal-based fertilizer
Worm compost, yard compost, compost tea

If you have a complete garden fertilizer already, one that you used in spring, use that again in mid-summer, following directions on the container.

However, the nutrient that is most often in short-supply by mid-summer is nitrogen. It can leave your soil by going into the air in addition to being washed away. If you can locate a higher nitrogen fertilizer product like the Alaska fish emulsion fertilizer or the seed-meal-based Nature’s Source Garden Plant Food, those can be good choices.

Composts are also good choices. To side-dress with these, be sure to rake them in — shallowly to avoid damaging roots — around the plants, covering it all with soil. Then water the compost in well to give the soil bacteria, fungi, and other small life-forms better access, to start breaking it down for use by plants. Use a big shovelful of yard compost, or a cup or two of worm compost, per plant. Worm compost is usually a more concentrated source of nutrients than yard compost.

If you make compost tea from your compost, to pour around your plants, root-damage becomes a non-problem. The tea may need to be poured around the plants more often than just once in mid-summer, for best effect. Compost tea applied to leaves can also slow down the growth of fungal leaf diseases. (Compost tea recipe is in the “treating mildews” section of the Summer Squash blog post.)

For gardens prone to leaf disease problems (pretty much every garden I have ever seen), regular use of compost tea can be helpful in extending harvests of some sensitive crops, like cucumbers and tomatoes, further into the summer.

Any gardener who has a small garden, but no compost pile or worm bin at home, might be interested in trying the compost tea bags. Sustane Compost Tea Bags are convenient, and no straining is required. I have used these to make tea for my own garden, and they seem helpful. When pressed for time, it is nice to not have to strain the compost bits out of the tea before filling a spray bottle.