Tomato Plants: Determinate, Indeterminate, Semi-Determinate – what do they mean?

There are two (or three) different types of tomato plants:

  • Determinate;
  • Indeterminate; and
  • Semi-Determinate.

Determinate

Determinate plants (also known as bush tomatoes) grow to a pre-determined sized and then flower and fruit over a short time (about two weeks or so). After this the plant will diminish in vigour and little new fruit will set. They tend to be smaller plants (up to four or five feet), sprawl about and don’t need pruning (in fact if you prune them it will reduce your crop). Depending upon the weight of fruit on the plant, they may or may not need support. Plants with standard sized fruit (e.g. Heinz H9129) will need some support to keep the fruit off the ground, plants with cherry sized fruit (e.g. Sweet Pea Currant) are much less likely to need support as the total weight of fruit will be less.

Determinate tomatoes are ideal if you want a lot of tomatoes all at the same time (e.g. for making batches of sauces) and if you are growing tomatoes on the patio where they are ideally suited to growing in pots. Commercial growers in places where the weather is suitable for outdoor growing tend to grow Determinate varieties so that they can harvest them mechanically all at the same time. For this reason, there are lots of different Determinate varieties available from the USA.

Indeterminate

Indeterminate plants (also known as cordon tomatoes) have fruit over a longer season. They tend to grow as a vine and need staking/support. In general they should be trained as a small number of vines (up to three) and supported with canes, strings or cages. The vines can grow huge (particularly when grown commercially) but in the greenhouse they are usually “stopped” when they reach the top of the greenhouse to encourage the set fruit to ripen. Most of the different sizes and colours of tomatoes are available as Indeterminate varieties.Examples of Indeterminate plants are Pink Brandywine, Red Berry and Ailsa Craig).
Indeterminate tomatoes are good in the greenhouse (where there is plenty of support) because they take up less floor space than determinate varieties. For this reason, commercial growers who grow under cover will generally grow Indeterminate varieties (many hydroponically) and heat and light their greenhouses to get a long season and large crop.

Semi-Determinate

Between these two types are the Semi-Determinate plants. Less vigorous than indeterminate plants, they typically grow three to five feet tall, will need staking and may require some pruning to limit the number of stems. Semi-Determinate are alright in the greenhouse (although you will need more space than for Indeterminate plants) but are less suitable for pots. An example of a semi-determinate plant is Gold Dust.

Choosing which varieties suit you best depends upon how much space you have and what varieties you are happiest with. We tend to grow Indeterminate and Semi-Determinate beefsteak, standard and cherry varieties in the greenhouse and Determinate cherry varieties in pots outside where we can move them around to catch the best of the weather to ripen them and provide snacks for the grandchildren.

If you go to our main website (here) you’ll find a full list of all the tomatoes we describe and each description includes the growth habits of the individual tomato.

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