Pruning Determinant and Undetermined Tomato Plants

Tomatoes are either determinate or indeterminate. This will depend on the tomato plant’s growth habit of stopping at a determined height vs a plant that keeps on growing indeterminately. Tomato plant suckers, or side shoots, are the growth that appears in the crotch between the stem and a branch. If it is an indeterminate and left to grow, the suckers will become another main stem with branches, flowers, fruit and will generate more suckers of their own. This will be a problem if the pattern continues indeterminately.

Determinant tomato plants have a predetermined growth cycle. When they reach a certain height they cease growing. If you are growing a determinate, pruning is of little importance. You might consider removing a few lower branches once it has grown a bit to assist in air circulation under the plant. The Bonsai Dwarf Red Cherry Tomato , for example, is a determinant type. It’s perfect for a smaller container such as the 5lt Hydro-Organic passive container. The  Bonsai Cherry Tomato doesn’t fruit until the branches are pretty much fully grown and then they set their fruit all at once. So pruning is not required. You will need to harvest all the tomatoes within a very short time of one another.

Indeterminate tomato plants you will want to have under growth control. If you leave all the suckers to grow, your plants will become heavy besides crowding out other plants. It’s incredible this vegetable plants eagerness to grow and live. The indeterminate growth pattern is exponential. From the main stem a suckers will keep forming in the crotch of all the leaves. These will grow into a vines shooting off suckers as well. At that rate you could get over crowded in a very short time. Removing some suckers will result in a more compact plant and larger tomatoes.

Training and Pruning an Indeterminate Tomato Plant

Your going to want to understand that an indeterminate tomato plant needs first to have something placed for support, trained then pruned constantly. To train the plant to stay within your support, you will have to “top-it-off” by cutting the “top” of the main stem. Afterwards, during it’s growth it will require constant pruning of the emerging suckers. Pruning suckers has a lot to do with the thickness of the stems and quality of the tomatoes.

Training an Indeterminate Tomato Plant

The plant will need to be trained to only grow in the space you have assigned to it. Tomato plants will ramble on and on given the chance. Controlling this large growth by topping off the plant after one or two suckers form is necessary. Perhaps the only exception is when you are placing the container where the plant can grow onto the arms of a Flying Nun Vivero or next to a trellis in the patio. But even then at some point your going to have to control the growth.

The first thing you want to do is set up a trellis, cage or bamboo branch for the vine to grow into. Bamboo branches are ideal for this purpose. They have a main stem with lots of random branches radiating outwards. Place the bamboo branch into the container while the plant is very young. Then, in the upcoming days, train it stay inside that space while maximizing light and air exposure. You do that in two ways, topping it off and trimming the sucker shoots. When to cut off  (top) the lead stem depends on the size of the container. Obviously the larger the container the more space it will have but topping the plant off after only one or two suckers will keep it inside the pots dimensions. To add a new stem, you need only to allow a sucker to grow just above the first flower cluster. Topping-off allows the plant stem to thicken and fatten the fruit. (Let me put it another way to make sure the idea is clear. The more stems the more flowers and fruit, but the tomatoes will be smaller. The less flower clusters, the larger the fruit.)

Pruning an Indeterminate Tomato Plant’s Suckers

The sooner you prune out the suckers, the easier it is. Tomato pruning is a trial and error process because all tomato varieties grow a bit differently and container sizes vary. As long as you have a strong main stem, it’s fine to leave a few suckers on the plant but then top it off and wait for the two you left to grow, extend and give off suckers of their own. They will always be in the new leaf’s crotch. Here is the challenge… in deciding how many of these suckers you leave on. Each one is no different than the top of your plant, except for the fact they were not the first in line. Try just one each. So now you have the main stem with two vines extending outward with one more extending from those. You better call it quite’s there and see what happens. There is a set of flowers at each joint. That means you have four setts of fruits. Some tomato plants get a lot bigger than others. If you are wanting to contain the tomato within the container, four fruits is normally just perfect. So after 4 5 clusters prune all the newly emerging suckers at least once a week..

Cuttings From any Tomato Plant

If you are in the position where you would like another tomato plant just like the one growing in your container, then simply take a cutting. Cut a small to medium sized branch with one or two shoots coming off it with a sharp clean knife. Place the cuttings in a cup or vase, changing the water every other day. In a week to ten days roots should appear on the bottom of the stem. You can place the rooted cutting in a seedling cup to finish off the rooting. Follow the instructions on how to use and hydrate the seedling cup.