Determinate and Indeterminate Tomato Plants

Tomatoes come in two distinct growing types: Determinate and Indeterminate tomato plants. A third type, semi-determinate, is also available but I treat it the same as I would an indeterminate.

Determinate tomato plants grow bush-like and usually no taller than about three feet. A tomato cage works well for these, and they require little pruning except for some leaf removal for air circulation. Determinate tomatoes will typically produce all of their fruit at once and then die. These tomato plants work well in patio containers. The advantage to determinate tomato plants is that they require less work and tend to have more resistance to disease.

This photo shows one of my determinate plants, "Saucey," in the foreground with indeterminate plants growing in the background. I only had to tie this plant once to the metal pole coming out of the center of the plant. As you can see, there can be a real contrast in height between determinate and indeterminate plants.

Indeterminate tomato plants grow tall and vine-like with lots of side shoots, although they do not have tendrils to grab onto supports. If left without support, this kind of tomato plant will sprawl all over the ground and be subject to disease and insects. Therefore, they require tall, strong supports and pruning to keep them healthy. To grow them under cover, you will need to build a structure that allows the tomato plants to grow about 6-8 feet tall. The advantage to growing indeterminate tomato plants is that they continue to produce fruit until killed by frost. Keeping them under cover will keep them producing longer--we continue to harvest from our indeterminate plants well into November.

Here is a photo of one of my indeterminate plants, "San Marzano 2". The support for this plant is two square cages stacked one on top of the other for a height of just over 5-feet. My indeterminate plants have all outgrown the top of their supports and are brushing the plastic ceiling of the garden covering.

Indeterminate tomato plants can also be grown in large containers with tall support. Here's a photo of a semi-determinate plant called "Andes" growing on my deck in a 1/2 wine barrel planter. I created a teepee-shaped cover for this plant using bamboo, twine and staples.

Before selecting tomato seeds or plants to grow, it can be helpful to figure out ahead of time whether determinate or indeterminate tomato plants will be best for your garden.

Seed catalogues, online seed sites and seed packages should have "Determinate" or "Indeterminate" listed for each tomato type. It can be trickier purchasing seedlings or plants--this should be listed on the plant marker but you may have to ask the nursery selling them to know for sure.

If you bring home a plant that you think is determinate but is growing like it's indeterminate--you could have an indeterminate plant by accident, but it's also possible that you have too much nitrogen in your soil producing an abundance of plant material and that makes your plant act indeterminate. Either way, you'll probably need to provide a taller support and do some pruning.

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