Choosing Between Determinate and Indeterminate Tomato Varieties

 Garden-planning time is underway! Seed catalogs have been arriving for a few weeks, and gardeners are reading descriptions for the hundreds of amazing tomato varieties available and trying to decide which ones to grow this year.

'German Gold' tomato

Among the many features that we ought to consider, along with disease resistance, heat tolerance, and whether we want canning tomatoes or fresh-eating tomatoes or both, is the growth type. Do we want determinate or indeterminate plants?

Understanding the differences in how determinate and indeterminate tomato plants grow and set fruit can help us choose the best type for our home garden. The differences can influence not only which type we choose, but also how the plants should be spaced, trellised, and pruned.

Difference between growth types

Plant size at maturity

The first difference that we can easily see in the garden is how tall 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 and the weather does not turn to freezing. Many heirloom tomato varieties are indeterminate types.

Semi-determinate tomato plants are a third growth type that you may see. As you might have guessed, the characteristics of semi-determinate plants are in between those of the other two 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 tomato fruit production and ripening -- when the fruits are ready for 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 tomato plants produce fruit all summer and into the fall, if they stay healthy. The fruits usually are spaced farther apart on indeterminate plants that they are on determinate plants.

Semi-determinate type tomato plants 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 held upright, 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.

Staking tomato plants

Up North, many gardeners prune and tie an indeterminate tomato plant to a single stake. In the South, I have seen that practice result in fruits ruined by sun-scald. In general, the Southeastern states have too much heat for too long for staking tomatoes to be a viable option.

However, I did see a remarkably productive patch of staked tomatoes in Florence, Italy, when I was lucky enough to visit there, that looked healthy and showed no scalded fruit. Summer is hot in Florence, but it is also dry, unlike the very humid summers of the Southeast. 

The close spacing in this tomato patch, in the image below, may not be as successful here, where tomato leaf diseases promoted by the high humidity can destroy our plants in a short span of time. I am thinking about trying a small patch of staked tomatoes this year, as an experiment.

Raised bed full of staked tomato plants in Florence, Italy

Caged tomato plants

Mostly, home gardeners in the Southeast rely on tomato cages to support their tomato plants, for all growth types. I learned at a Georgia Organics conference, several years back, that caged plants produce more tomatoes per plant than trellised or staked tomatoes. This makes caging a great option for small gardens.

Determinate tomato plants, since they stay smaller, can be supported by less robust structures than indeterminate plants. The indeterminate growth types 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 sturdy wire mesh. Find a mesh that has its wires about 6-inches apart, and create a cylinder that is about 18-20 inches across (diameter). 

The wire cylinder makes a good cage/support for tomato plants, but it will need to be held upright with stout posts, to keep it from blowing over in a big wind or being toppled by the heavy top-growth of an especially robust tomato plant.

Another caging option is a product called a Texas Tomato Cage. These strong, and collapsable (for easy storage!), tomato cages are awesome -- I use them -- but they are pricey.

Pruning the different types of tomato plants

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."

If you feel the need to prune, thin the number of main stems of indeterminate plants to just three or four, early in their growth, then leave them 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.

The Texas A&M article linked above also adds this about pruning determinate tomatoes: "Do not prune plants of determinate hybrids if you plant to trellis and support them with twine woven around wooden stakes."

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:

Characteristics of 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 ripe 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.
• Shorter productive lifespan also means that gardens that are troubled by a lot of late-summer tomato plant diseases have an improved chance to harvest plenty of tomatoes before the diseases destroy the plants.
• Smaller-growing determinate types can fit in small gardens that might not contain an indeterminate type. You can plan to have another determinate type plant ready to replace the first one, when it quits making abundant tomatoes. You can have a second harvest in the fall!

Characteristics of indeterminate tomato plants

• Produce over the whole summer, as long as they 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. One year, 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?

'Wuhib' is a semi-determinate paste-type tomato that did great in my old North Georgia garden

Examples of determinate and indeterminate tomato varieties

Back in North Georgia, many gardeners that I knew were dedicated to particular varieties. Some always grew 'Celebrity', some planted dozens of 'Park's Whopper' every year, and some were 'Better Boy' loyalists. 

I am still learning about varieties that are best for the Mississippi Gulf Coast, but so far, the same varieties I've grown from this list are still proving to be successes.

Some determinate tomato varieties with good disease resistance for the South:

• Celebrity (hybrid)
• Dixie Red (Hybrid)
• Mountain fresh (hybrid)
• Patio Choice Yellow
• 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 with good disease resistance for the South:

• 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)

Making your final tomato variety selection 

Did I already say the part about reading variety descriptions carefully as you choose your tomato plants? This works best if you are growing from seeds, since the catalogs give more detail than plant-tags in a garden center. But, checking varieties online, on your phone, as you face the racks of plants in a garden center can be helpful.

The descriptions contain clues about whether a variety is a good match for your garden. For example, if you live in the Southeast, and a tomato variety description says that it produces well in dry conditions, the variety might not be a great match for the rainy, humid Southeast.

Also, consider this: my copy of the 2023 seed catalog from Southern Exposure Seed Exchange says that its 'Cherokee Purple' tomato plants stay shorter than the 'Cherokee Purple' plants grown from seeds of some other suppliers.  This statement presents a topic worth understanding.

The same variety offered by different suppliers might not be the exact same plant. If you have grown a variety from one seed supplier, and it did great in your yard, be aware that seeds of the same variety from a different supplier might not give the same results. 

The plants may be generally the same, but different in key particulars.

I have known a lifetime-gardener who grew 'White Mountain Half Runner' beans for decades, but she would only buy from one supplier -- Morse (now Ferry Morse). She said that the same variety from other suppliers did not actually produce the same beans, in flavor, abundance, and growth habit.

So, when you find a tomato variety that you love, that meet the needs of your household, and that does well in your yard, remember (or write down) the name of the seed or plant supplier.