How to prune tomato plants to double your harvest
In addition to watering, fertilizing, and weeding, pruning your tomato plants is key to a bountiful harvest.
Key Takeaways
- Knowing the difference between determinate or indeterminate tomatoes.
- Not all types of tomatoes need pruning
- Why pruning is an effective step in tomato growth.
If you haven't checked on our tomato plants for a couple of days and are amazed how much they grew, you won't need much convincing that pruning is an important part of tomato-care routine. It is a simple technique that gardeners use to keep plants tidy and disease-free, harvest larger fruits that ripen earlier, and produce a maximum yield.
Not all types of tomatoes need pruning, and we'll explain which types of tomato plants you should prune and why. Then we'll give you the full rundown on why to prune tomato plants, when, which parts, and how to prune, as well as pruning mistakes to avoid.
Pruning Determinate Vs. Indeterminate Tomatoes
When you purchase a tomato plant from a nursery, the container label should identify the plant as either determinate or indeterminate.
Determinate tomato varieties are often referred to as "bush" tomatoes because they do not continue growing throughout the season and stop at a height of around 4 feet. Determinate varieties such as 'Roma' produce one large crop, which is ideal if you want a lot of tomatoes in a short period for freezing, canning, or making tomato sauces. Determinate tomatoes do not need to be pruned, though you can remove growth at the base of the plant that would trail on the ground.
Indeterminate tomato varieties, such as 'Beefsteak' and 'Brandywine', are vining plants that continue to extend in length and produce fruit throughout the growing season. Pruning indeterminate tomatoes helps to keep the huge vines under control and encourages the production of tomatoes large enough for your classic BLT sandwich or tomato pie, instead of excessive foliage and many smaller tomatoes. Many cherry tomato varieties are indeterminate as well, and proper pruning will guarantee clusters of tomatoes throughout the entire season.
Why You Should Prune Tomatoes
While it is possible to grow tomatoes without pruning them, this small yet effective extra step is highly recommended for several reasons.
Improved Airflow Reduces Disease
Pruning reduces the amount of foliage, which results in a less dense plant. This allows for more air to flow among the stems. Pruning also removes tomato stems touching the ground. Especially when the soil is wet, this can lead to disease. A well-pruned plant will also dry faster after a rain, so tomato plants are less susceptible to diseases that develop from prolonged moisture, humid weather, and poor air circulation.
Common fungal, bacterial, and viral diseases that infect tomato plants include late blight, leaf mold, bacterial spot, and anthracnose. They all thrive in poor air movement due to dense foliage. Pruning tomato plants is an important part of disease prevention.
It's Easier To Spot Pests
Fewer leaves also make it easier to spot insect pests that hide in thick, dense foliage. Common enemies of tomato plants are aphids, hornworms, thrips, whiteflies, tomato psyllids, fruitworms, and flea beetles. Spotting pests early allows you to take the necessary steps before a few insects turn into an infestation. Larger pests can easily be picked off, while others may require spraying with an organic pesticide labeled for vegetables.
Tomatoes Grow Bigger And Ripen Faster
Pruning at the right time directs the plant's energy toward creating and ripening fruit instead of producing excessive foliage. Overall, you will probably have less fruit on a pruned plant, but the fruit will ultimately grow bigger.
When a plant has fewer leaves and less fruit, the fruit also ripens faster. This is an advantage in areas where the growing season is short because of early fall frosts.
Plants Stay At A Manageable Size
Pruning keeps the size of tomato plants under control, especially with container plants. Removing the suckers gets rid of extra vines that will cause a tomato plant to outgrow its space, eventually turning into a tomato jungle. This allows you to space your tomato plants a bit closer together and also makes more room for other vegetables in the garden.
If you want to grow tomatoes in containers, choose compact varieties. Depending on whether it's a determinate tomato such as 'Tiny Tim' or indeterminate variety such as 'Sweet 100', your container tomatoes will also need pruning.
Start pruning your tomato platns when they are about 12 to 18 inches in height, which is typically the time when the first suckers appear.
Prune tomato plants in the early morning on dry days. Do not prune the plants if they are wet from rain, dew, or sprinklers.
The suckers should be removed when they are no larger than 2 to 4 inches long so the plant won’t spend energy growing new branches off of the main ones. Prune indeterminate tomatoes at least every couple of weeks, preferably more often, as new suckers appear on the plant. Continue to prune the plants until about four weeks before the first expected frost.
How To Prune Tomatoes
Pruning indeterminate tomatoes is really a simple process.
Pruning At Planting Time
The first pruning should be done when you plant the tomatoes. Remove any lower leaves or stems that touch the ground after planting. Then pinch off any flowers on the plant until it reaches a height of 12 to 18 inches, so the plant can focus on root growth.
Always wear gloves when pruning tomatoes. The foliage causes allergic skin reactions in come people, leading to itching, rash, swelling, or redness. It also leaves pesky green stains on hands and under fingernails.
- Always disinfect your pruners with a 10% bleach solution (1 part bleach to 9 parts water) or rubbing alcohol before starting and as you move from one plant to another to prevent the spread of disease.
- Remove any yellow leaves.
- Remove any foliage or stems growing at the base of the plant. Stake up or remove any branches that are low-hanging or touching the ground.
- Look for the tomato "suckers," which are the side shoots that grow in the "V" space between the main stem and the main branches of a tomato plant. Pinch small suckers off with your fingers, but use your pruners for larger ones.
Final Topping
At the end of the growing season, about four weeks before the first frost, do one final pruning called topping. Cut off the growing tip of each stem, which encourages the last batch of tomatoes to ripen before fall.
Common Pruning Mistakes
To avoid stressing your plant or introducing harmful bacteria, here are mistakes to avoid when pruning your tomato plants:
- Using dirty tools introduces bacteria and fungi, which is why you need to clean your tools with rubbing alcohol or bleach before use on each plant.
- Don't prune severely diseased plants; they should be pulled and discarded before they infect the rest of the patch.
- Don't go days without checking on your tomato plants. Ideally, visit them every other day, so you can remove suckers as they emerge. Waiting too long to remove suckers means the plant spends its energy on unnecessary growth that could be spent on the fruit. Removing large amounts of foliage at once to get the growth back under control is stressful for the plant.
- Wait until plants are dry before pruning. The risk of bacteria, viruses, or fungi spreading in wet plants is much higher.
- Give tomato plants adequate support with a sturdy, tall trellis or tomato cage so they don't become top-heavy and unmanageable. Otherwise, you may end up needing to prune more heavily and lose some of your harvest.
