Many of the most well-known salad greens, like lettuces, and potherbs such as spinach and collards, are cool season vegetables. That means that they do not stand up well to summer heat, especially the intense and humid heat of the Southeastern U.S.
However, the onset of summer does not necessarily mean the end of garden salads and cooking greens. It does, though, mean that our summer salads and cooking greens might look and taste a little different from those we enjoy in cooler weather.
What is the difference between salad greens and potherbs? In general, we eat the salad greens raw and the potherbs cooked. Some greens can be used both ways. The list below is not a full list of all the possibilities; it is a start, though, to help diversify our gardens and our diets.
Salad greens we can grow in summer
Lettuces
In the Southeastern U.S., growing full-sized summer lettuces — that are not too bitter to eat — is difficult in a home garden. However, some gardeners in the Southeast cannot imagine life without garden-fresh lettuce. The good news is that it is possible to keep growing lettuce here, in the summer heat, but the gardener will have best success when harvesting the lettuce as “baby greens”.
That means harvesting the lettuces when they are only about four inches tall, letting them regrow once (maybe) for a second harvest, then starting over with another bunch of seeds. Lettuce plants in the garden eventually will turn bitter in the summer heat. Planting a new patch of seeds every few weeks lets a gardener harvest fresh lettuce that is still sweet.
Planting the lettuces in a spot that gets afternoon shade, with rich moist soil, and not allowing the soil to dry out, can help delay the bitterness.
Chicories can be grown and used the same way in summer – harvested small, grown in rich, moist soil, in afternoon shade, to minimize the bitterness.
Purslane and Jewels of Opar
These plants are grouped into the same plant family: Portulaceae. Both have leaves that are a little tart, or maybe lemony in flavor, and succulent — plump with an interesting interior that skirts the edge of slimy.
Purslane pops up in my garden on its own. I have never planted seeds for it, but buying seeds is possible if this plant doesn’t just magically appear in your summer garden. Baker Creek sells seeds for both green purslane and golden purslane. They grow well in full sun.
Purslane seedlings in the garden. 
Purslane plant in a space between leaves of a squash plant in the home garden.
Jewels of Opar (see photo near top of this article) is a cultivated plant that self-sows in many yards after the first plant becomes established. I have written about Jewels of Opar in a previous blog post, but the best news is that the plant is attractive enough to grow in a flower border. If your garden is in the front yard, this is a salad green to try.
Parsley
The strong flavor of parsley is not a favorite for everyone, I know, but this green is an essential ingredient in the Mediterranean salad known as Tabbouleh. The Lebanese version includes a lot more parsley and less bulgar wheat than some versions, and it is a good argument for including more parsley in other kinds of summer salads.
Parsley may be my favorite summer salad green. My garden has four parsley plants in it right now, growing to hugeness.
Potherbs we can grow in the summer garden
Swiss Chard
Some Swiss Chards languish in the summer heat, but I have had good success with a variety called ‘Perpetual spinach’. If you enjoy beet greens, this is an excellent similar-flavor substitute for summer.
Smaller leaves, harvested while still tender, can also be used as a salad green.
Amaranth
Leaves of amaranth wilt pretty quickly when they are cooked, so have the garlic chopped and ready to go before adding the leaves to a hot pan with olive oil. Like for many other plants, new small leaves are tastier than older, larger leaves.
Some varieties of amaranth grow very tall and are cultivated for their seeds, rather than as greens.
Look instead for a variety like Baker Creek’s ‘Green calaloo’ or ‘Chinese multicolor spinach’. These are cultivated for their more delicious leaves.
Malabar spinach
Many years ago, when I was growing malabar spinach, our substitute mail-carrier was from Barbados. One day, when she was delivering the mail, she stopped to ask about our garden. She said that our malabar spinach was the green her mother cooked for her family back home. She called it REAL spinach. I quickly harvested a large pile of leaves for her to take home, and told her to stop by any time for more.
Once established, this crop is a vigorous vine. Be sure you have plenty of room and a strong trellis before planting this one. The thick leaves are more mucilaginous inside than most cooking greens, but the slimy aspect is lessened with cooking. According to our mail carrier, adding a few chopped leaves to soups is a good way to work your way toward eating them as a stand-alone dish, if they don’t appeal at first.
I never managed to love this crop, so we don’t grow it any more. I have met, though, plenty of gardeners who do love malabar spinach and who can’t imagine not growing it in the summer garden.