How to Prune Indeterminate Tomatoes for Maximum Yield

When planting tomatoes, the main goal is to receive the maximum yields possible. You may want to remove the unnecessary suckers and leaves in order for the plant to maximize the use of nutrients for the production of fruits.

Selectively removing unwanted plant growth from indeterminate tomatoes can help to improve production and the taste of the harvested fruits. Further, removing a set of older leaves improves air circulation and keeps the plant off the ground. This reduces the chances of fungal diseases like early blight and septoria leaf spots attack.

Does Pruning Tomatoes Increase Yield?

Yes, pruning tomatoes increases yields. It helps the plant to direct its energy towards fruit production rather than the production of foliage. Pruned plants tend to produce larger fruits as compared to those left alone. By having less foliage, the plant is able to direct its energy toward developing larger fruits.

Pests and diseases attack is among the common causes of poor yields in tomatoes. Pruning ensures the plant receives free air circulation and stays off the ground. Tomatoes are at risk of fungal infections like early blight and septoria leaf spots if they are lying on the ground. Maintaining the plant healthy throughout the season guarantees high yields.

In addition, when plant leaves stay permanently in the shade, they produce less energy. This can be corrected by pruning or staking the plant to remain in an upright position. It also ensures all the leaves receive adequate sunlight. Plants use sunlight in the process of photosynthesis to boost growth and production.

How to prune indeterminate tomatoes

There are two main types of tomato varieties namely indeterminate and determinate. The common indeterminate varieties include Beef Master, Big Boy, Black Prince, and German Queen. Most cherry and heirloom tomato varieties belong to this category. 

On the other hand, determinate varieties are Amelia, Better Bush, Ace 55, Biltmore, Patio, Mountain Pride, Heinz Classic, and Headmaster.

Indeterminate tomato variety grows like vines and requires a lot of staking and pruning to keep it upright while determinate variety requires less or no pruning and staking. They can contain themselves and direct their energy toward fruit production.

The common mistake that many gardeners do is pruning their tomatoes too late. Watching out for the following tell-tale signs will help to guide you on whether your plants are ready for pruning or not:

• Check for yellowing of lower leaves: Yellowing of the first set of leaves is among the early signs that will tell a tomato is ready for pruning, it is an indication that the plant no longer needs them. You can start to prune when you notice the change.
• Check for sprouting of suckers: Suckers are small new branches that emerge at the center of the leaves and branches of indeterminate tomato plants. They are the branches that you would want to remove. When left to grow, they can produce fruits but will compete for nutrients and other resources with the main plant. The aim of removing them is to have larger tomato fruits.
• Check for flowers: The plant is mature when you start to observe the appearance of flowers. At this point, you can go ahead and start pruning. During flowering, the plant requires a lot of energy. Cutting off the suckers and older leaves can help the plant to stay healthy and produce larger fruits.
• The techniques to use for pruning: The quality and quantity of fruits to get from tomato plants is determined by the techniques you use during the pruning process. Be gentle when removing the suckers and older leaves to minimize injuries to the plant.

Pruning steps

Once you are sure that your tomatoes need pruning, here is what to do:

1. Prune all the suckers below the first cluster of flowers

Removing all the suckers below the first cluster of flowers is one way of ensuring that the nutrients are directed toward the development of the fruits. Suckers are not removed when pruning determinate tomatoes, instead, only yellow or dead leaves are removed.

To remove the sucker, grab it at the base using your thump and the forefinger. Bend it back and forth until it plucks away. This procedure should be done when the sucker is still young to prevent serious injuries to the plant.

2. Do not prune thicker suckers

Snapping off thicker suckers can cause serious injuries to the plant. Use a Missouri pruning method on suckers that are thicker than a pencil. This method is done by pinching the tip of the sucker. Leave behind a set of leaves for photosynthesis and protection of the fruits from sunscald.

3. Remove the lower yellow leaves

It is normal for the lower set of leaves to turn yellow as the plant matures. However, you should remove them once you start to notice a change in color. Yellow leaves use more energy from the plant than they produce. They can also act as pest and disease transportation media.

4. Remove some fruit-bearing tissues

When all the fruit-bearing tissue is left to develop, there may be a competition for nutrients and other resources. The fruits will be many but too small size. For larger and healthy fruits, you can remove some clusters of fruit-bearing tissues.

5. Top the plant

Remove the terminal shoot when the fall of frost is around the corner or when the plant hits the ceiling of your greenhouse. The plant will use its nutrients for the development of the fruits instead of supporting further growth.

Tomato pruning mistakes people make

There are some pruning mistakes that many gardeners do:

Pruning excess foliage

The plant requires enough leaves to provide itself with energy through the process of photosynthesis. Removing too many leaves can cause stress to the plant. The leaves also act as a shade to protect the fruits from sunscald. Pruning especially during summer weather conditions can damage the fruits.

As a rule of thumb, do not remove more than one-third of the plant’s foliage at a time.

Pruning too late

When growing indeterminate tomato varieties, it is detrimental to prune late when the plant has already established itself. Cutting thick suckers may cause injuries that allow in bacterial infections. The main aim of pruning is to keep the plant leaves off the ground, maintain an upright posture and maximize the use of nutrients. Late pruning may not give positive results as it would have been done earlier.

Using unsterilized tools

Dirty and unsterilized tools can introduce bacterial or fungal infections to your plants. Clean the tools properly using a disinfectant or clean soapy water. To avoid the spread of diseases, do not use the same shears to cut old diseased leaves and the young suckers.

Pruning wet plants

Tomato plants are prone to fungal infections. Pruning when the leaves are wet can encourage the spread of diseases from infected plants to others. Be sure to wait until when the plant is completely dry.

Final Thoughts

Pruning indeterminate tomatoes promotes maximum yields by ensuring there is maximum utilization of sunlight and nutrients. A healthy plant equals high production, pruning ensures the plant is less attacked by pests and diseases.