Understanding Determinate and Indeterminate Tomato Plants

Tomatoes are a staple in vege gardens but by halfway into the growing season you may be faced with an overgrown tangle of vegetation hiding clusters of half-ripened tomatoes or pests that are feasting on them. So, to make sense of our vege plots we need to work out what we have.

Tomatoes fall into two main categories: determinate and indeterminate. Knowing the difference between these two types can contribute to a better harvest.

Determinate tomato plants, often referred to as "bush" tomatoes, have a compact growth habit. They grow to approximately 1.5 metres and then stop. This type of plant produces all its fruit in a relatively short period, usually within two weeks and is widely used by commercial growers. After this fruiting period, the plant's energy focuses on ripening the fruit rather than producing new blossoms. Determinate tomatoes are ideal for gardeners with limited space or those who prefer to can or process tomatoes all at once. Most determinate varieties need a trellis, but some varieties have a very sturdy main stem and don't need much support; just a stake.

When pruning derterminate plants you don't want to remove too many branches otherwise, you will reduce your overall yield.

The aim is to tidy up the plant, stopping it from becoming too thick and preventing air flow amongst the branches and fruits.

To effectively prune your indeterminate tomatoes, first remove suckers, as we did with our determinate plants. As the plant grows, remove the lower leaves that are close to the ground. These leaves are more prone to diseases and pests. Pruning them improves air circulation and reduces the risk of soil-borne diseases.

Maintain one to two main stems. This focuses the plant’s energy on fewer, but more productive, stems. To do this, choose a strong sucker or two, and allow it to grow while removing all others. As new suckers develop, pinch them off when they are 4-8 cm. This can be done with your fingers or pruners.

Toward the end of the growing season, when the summer heat arrives, you can "top" the plant by cutting off the top of the main stem. This stops the plant from growing taller and redirects its energy into ripening the remaining fruit.

Whether you are growing determinate or indeterminate tomato plants, they will both thank you with abundant, healthier harvest following pruning through the season.

Enjoy!

The best time to prune is when the plant is young. Begin by removing any suckers, these are shoots that appear between the main stem and branches, they tend to grow at a 45-degree angle. These branches provide smaller fruit and take energy away from the other fruiting branches, affecting the overall yield.

Next, remove any branches growing towards the main stem. The branches will block sunlight from reaching other leaves and prevent airflow.

Finally, remove any branches that look diseased or damaged.

Indeterminate tomato plants continue to grow and produce fruit throughout the growing season. These plants can reach two metres or more and require sturdy support structures like cages or trellises. Benefits of this type are larger plant size which can lead to a more abundant overall harvest, and better flavour due to vine ripening. Pruning indeterminate tomato plants is important for plant health, air circulation, and higher fruit production. We stock Tommy Toe, Sweet Marbles, and White Cherry tomato plants. These are hot-climate, early fruiting varieties of indeterminates.