Understanding the differences in how determinate and indeterminate tomato plants grow and set fruit can help you choose the best type for your home garden. The differences can influence not only which type you choose, but also how the plants should be spaced, trellised, and pruned.
Differences between the growth types
Plant size at maturity
The first difference that we can easily see in the garden is how large the mature plants become.
Determinate tomato plants usually grow between one and five feet in height, which means they are less likely to overwhelm a small garden. Many patio and container type tomatoes have a determinate growth habit.
Indeterminate tomato plants can grow to become much taller, as much as 8 or more feet tall. Main stems of plants in this growth type continue to grow in length/height for as long as they are healthy. Many heirloom varieties are indeterminate type tomatoes.
Semi-determinate tomato plants are a third growth type that you may see. As you might have guessed, the characteristics of a semi-determinate plant are in between those of the two other types. These plants are a little less tall and rangy than indeterminate type tomatoes, but not as compact as determinate types. This growth type can work well in a small garden.
Differences in when they set fruit
Timing of fruit production and ripening — when it is ready to harvest — is another difference between the growth-types that we can see in the garden.
Determinate type tomato plants set almost all of their fruit within a few weeks, and then their productivity slows way down. The fruits form on side-branches that are fairly closely spaced on the plants.
Indeterminate type tomatoes produce fruit all summer and into the fall, if they stay healthy. The fruits are spaced farther apart on indeterminate plants than they are on determinate plants.
Semi-determinate type tomatoes can produce fruit through the whole season, but they may not be as productive toward fall as an indeterminate type.
Trellising the types of tomatoes
Tomatoes need to be trellised one way or another to keep the fruit off the ground. The fruits are more likely to rot or attract small animal pests if they touch the ground.
Up North, many gardeners prune and tie an indeterminate tomato plant to a single stake. Here, that practice would result in a lot of ruined fruit, from sun-scald. We have too much heat for too long for staking tomatoes to be a reliable option.
Home gardeners in the South mostly rely on tomato cages to support their tomato plants, for both growth types. Research has shown that caged plants produce more tomatoes per plant than trellised tomatoes (I learned this at a Georgia Organics conference), so caging is a great option for small gardens.
Determinate tomato plants, since they stay smaller, can be supported by less robust structures than indeterminate plants. Indeterminate tomato plants need strong, tall structures.
Most garden centers do not sell sturdy enough cages or supports for indeterminate tomatoes. One option is to make your own out of strong hog fence or other wire mesh. Find a mesh that has its wires about 6-inches apart, and create a cylinder that is about 2-feet across. The wire cylinder makes a good cage/support for tomato plants, but it will need to be held upright with stout posts. Otherwise, a tall, heavy plant will topple the whole thing.
Another option is Texas Tomato Cages. These strong but collapsable tomato cages are awesome — I use them — but they are pricey.
Another great aspect of caging a tomato plant, instead of trellising or staking, is that it reduces the amount of pruning needed. Texas A&M Extension goes so far as to say this about pruning tomatoes: “Suckering or pruning the plants is not necessary when you use cages.”
Clemson Extension says that, if any pruning is done on caged tomato plants, it should be early and just once, adding this about caged tomatoes and less pruning: “Caged plants are less prone to the spread of disease from plant handling and do not have open wounds from de-suckering and tying them up frequently as with staked plants.”
If you feel a need to prune, thin the number of main stems of indeterminate plants to just three or four, early in their growth, then leave the plant alone.
For determinate plants, any pruning should be very early in the plant’s life, just enough to guide its growth. Pruning this growth type can result in lower production of tomatoes.
Tomato plant spacing in the garden
Recommended spacing for tomato plants in the garden for the South, for plants in cages, is 3-4 feet, for both types. Determinate types tolerate a tighter spacing than indeterminate plants.
However, when plants are in cages, a wide spacing allows more air-flow between the plants. Good air-flow helps the leaves dry out in damp weather, and as a result reduces the spread of leaf-diseases in the garden.
When first setting out plants in the garden, when they are little transplants in 4-inch pots, the 3-4 foot distance looks absurdly large. As the plants grow, though, you may wish that you had given them 5 feet instead of just 3 or 4, if you planted a very large-growing variety.
Which type is best for my garden, determinate or indeterminate?
The different growth habits have benefits and drawbacks. Here are some things to think about as you plan your garden:
Determinate tomato plants
- Ripen most of their fruit in a short time-frame– this is great if you plan to do some canning, where having a lot of tomatoes all at once is helpful.
- Shorter productive-lifespan means that there will be space in the garden in late summer for other crops. This can be good if you are short on space but want more variety from your garden.
- If space in your garden is so tight that an indeterminate variety won’t fit, you can plan to have another determinate tomato plant ready to replace the first one, when it quits making abundant tomatoes. You can have a second harvest in September!
Indeterminate tomato plants
- Produce over the whole summer, as long as the plants stay healthy. This is great if you like to have a few tomatoes to eat every week.
- Long-time in the garden means these plants are exposed to more plant diseases and pests for a longer time than determinate plants. Relying on disease resistant varieties becomes increasingly important.
- Many heirloom varieties are indeterminate, and the heirlooms offer a wide range of flavors that is hard to find in determinate types.
- These can grow to be quite large. Read the variety information carefully. I grew a ‘Matt’s Wild Cherry’ that erupted out the top of its cage and sprawled across 10-feet of garden. Do you have room for that?
Examples of determinate and indeterminate tomatoes
Some determinate tomato varieties, with good disease resistance for the South:
- Celebrity (hybrid)
- Dixie Red (hybrid)
- Mountain Fresh (hybrid)
- Patio Choice Yellow (hybrid)
- Homestead 24 (old, open-pollinated, but not heirloom) may be semi-determinate
- Long Keeper (heirloom, I think) a storage tomato
- Rutgers (old, open-pollinated, but not heirloom) may be semi-determinate
Some indeterminate tomato varieties:
- Park’s Whopper (hybrid)
- Better Boy (hybrid)
- Cherokee Purple (heirloom)
- Sweet 100 (hybrid) cherry tomato
- Mortgage Lifter (heirloom)
- Arkansas Traveler (old, open-pollinated, but not heirloom)
- Black Krim (heirloom)