No doubt you’ve come across the words ‘determinate’ and ‘indeterminate’ when reading about tomatoes. It can be a bit confusing to determine what determinate and indeterminate mean. Here I’ll provide some insights which should help to clear up any confusion.
Among the various classifications, you will likely – or at least possibly – see on tomato plant labels or on tomato seed packets is determinate or indeterminate.
The terms make reference to a tomato plant’s growth habit. That basically comes down to bush-type growth (bushier) or vining-type growth (taller), respectively.
If you didn’t stake your tomato plants inevitably they would begin to sprawl along the ground – a bit like some of the vigorous Clematis and rose varieties do. So, if they are left unto nature, tomato plants, in general, would not do a particularly good job of it. Why?
Their natural tendency is to ‘wander.’ Their natural tendency is to grow horizontally. That tendency would inevitably lead to a wet, tangled-up mess of a plant trailing along the soil surface. In turn, this means that tomato plants would be a center of attraction for pests and diseases.
This natural growing scenario is bad enough for determinate tomato varieties. But it’s even worse for indeterminate varieties because ‘indeterminates’ grow far longer than ‘determinates.’
What is a Determinate Tomato?
A determinate tomato plant is one that grows to a particular size when it reaches maturity. All of the fruit ripens within a short period of time – normally, that would be around two weeks.
After the first flush of fruit, a determinate tomato plant will start to diminish in terms of its vigor. This spells disaster as far as more fruit is concerned – there will be very few if any new fruit once the plant begins to diminish.
Frequently, and you’ll very likely have come across it yourself, determinate tomato plant varieties are referred to as ‘bush.’ This is because they stop growing in length at a certain point in time within the growing season.
In general, determinate tomatoes are smaller than indeterminate varieties. Most determinate tomato plants will only reach around 4-5 feet in height. In terms of meters, that’s 1.2-1.5 m.
Sucker removal from determinate-type tomato varieties is, as a general rule, not really required. That’s because the suckers will, again – as a general rule, not have a tendency to grow much, if at all.
In spite of the compact size, caging or staking (or you can do both if you wish) is still a recommendation for determinate tomato varieties.
This is because the plants will need to support a boatload of plump, juicy fruit once the fruit has set and begins to ripen. For obvious reasons, this weighs heavy on the branches.
There are many Roma tomato varieties that are determinate – for example, ‘Amish Paste‘ and ‘San Marzano.’ Others have been specifically bred so they become determinate in nature. In the latter category, we have ‘Marglobe,’ ‘Celebrity,’ and ‘Rutgers.’
If you’re keen on harvesting copious tomatoes within a relatively short timespan – you may wish to make a large batch of sauce, for example, then growing determinate tomato varieties is a wise decision.
What is an Indeterminate Tomato Variety?
An indeterminate tomato plant variety is one that continues to grow in length throughout the entirety of the growing season. This is contrary to determinate varieties and what they do: determinate varieties hit a certain height when mature and then set fruit on one go.
Indeterminate varieties are often referred to as ‘vining’ tomatoes because of this growth habit.
Indeterminate tomato varieties don’t quit on setting and ripening fruit until the growing season comes to an end. They continually set fruit throughout the entire season. And they only stop setting fruit when the plants are hit by early (or mid-, depending on where you are) fall frosts.
Indeterminate varieties provide growers with a nice slow, steady supply of fruit. Again, that’s very different to determinate tomato varieties that cater to a one-time excessive harvest.
Fruit on indeterminate varieties has a tendency to begin ripening a little later on than determinate tomato varieties. That’s because indeterminate varieties spend a lot more time, and energy, growing far taller than determinate varieties do.
Most tomato varieties are, in fact, indeterminate. This includes most cherry-type tomatoes and most heirlooms as well.
Many dwarf varieties of tomato plants are likewise indeterminate.
How to determine if it’s an indeterminate variety?
If it grows tall and lengthy (though it doesn’t necessarily have to fit this category) and/ or the plant continually sets flowers and fruits throughout the growing season, for example, ‘Sungold,’ ‘Brandywine,’ ‘Sweet Million,’ ‘Big Boy,’ ‘Beefsteak,’ then you have yourself an indeterminate tomato variety.
Early producers such as ‘Early Girl’ and ‘Celebrity’ are indeterminate. Nevertheless, because these varieties have a tendency for maturing earlier and dying back prior to the season’s end they have earned themselves a different label – semi-determinate.
While most people will stake (or cage) any type of tomato, with the indeterminate varieties you’ll need to use the sturdiest and the tallest stakes. These plants really do need substantial staking, or indeed, substantial caging. After all, many indeterminate varieties reach heights of up to 10 ft (3 meters ) or sometimes higher still.
You can, though, grow your tomato plants upside down. This way, the plant becomes a hanging vine and it eliminates the requirement for support. Plus, as a hanging vine the fruit remains well away from the ground and the plant can grow in a more open manner.
The good thing about a more open growth habit is that sunlight can reach into the center of the plant and the plant is more open which means more airflow throughout the plant and that means less likelihood for some diseases occurring.
Which is Better – Determinate Tomato Varieties or Indeterminate Tomato Varieties?
Now, which one should I choose to grow? Will it be a determinate variety or an indeterminate variety? Hmmm…
To make the choice easier: both of them come with pluses and both come with minuses. Does that make it easier for you to choose? No, obviously not.
But these factors will make the choice easier: it’s more dependent on what you wish to use your tomato crop for. It’s also dependent on your own growing season – how long the growing season is.
If you wish to make sauces from your tomato crop harvest, the choice would likely be a paste tomato. Paste tomatoes are typically determinate varieties.
Want to eat your tomatoes pretty much straight from the bush? Want to enjoy a supply of fruit that is season long? Opt for the indeterminate varieties.
If your growing season merely lasts for a couple of months or so, a better choice for you would likely be determinate.
There are, though, some short-season varieties that are indeterminate such as those early-maturing varieties mentioned above.
So the best way to tell which variety, that being indeterminate or determinate, is going to be best for you is to experiment and see which ones work best where you are.