It’s a controversial topic that feels a little counterintuitive. Gardeners may argue different points of view, but most horticultural knowledge agrees that pruning is an essential part of cultivating tomatoes.
Tomatoes benefit from four different types of pruning – suckers, foliage, fruits, and tomato tops. Tomatoes need to be cut back regularly during the growing season, ideally once per week after transplanting. Make tomato pruning part of your weekly gardening routine for the healthiest and most productive plants.
The first time I had to prune tomatoes, I struggled. It felt more than a little cringy, and I spent way too much time worrying about whether or not I was pruning my precious tomatoes correctly. Was I hurting the plants? Opening the door for disease? Was I even removing the right suckers?
I’m here to save you from making the same mistakes I made so you can prune your tomatoes with confidence! Read on to learn the importance of pruning tomatoes and use the step-by-step guide to learn exactly when and how to prune tomatoes.
Why You Should Prune Tomato Plants
Tomato pruning is a somewhat debated subject in the garden. While most growers agree that pruning tomatoes result in larger and better-tasting fruits, pruning obviously reduces tomato yields.
Some gardeners will argue that leaving suckers provides more surface area for photosynthesis to occur, ultimately resulting in more fruits with high sugar content. Other growers insist that removing suckers concentrates the already available sugars into fewer fruits, resulting in smaller but sweeter harvests.
According to the Lee County Center of the North Carolina Cooperative Extension, it all comes down to a choice between quality and quantity:
“Sufficient pruning will leave your plants with shorter vines and larger fruit that will mature earlier. Pruning combined with staking keeps vines and fruit off the ground, helping to control diseases. Although pruning requires some effort, the benefits of it are more good-sized fruit, and easier harvesting (Daughtry and Gaster).”
https://lee.ces.ncsu.edu/2018/05/try-pruning-to-get-larger-tomatoes/
Different Pruning Techniques
Pruning tomatoes encompasses removing a lot more than just suckers. While removing tomato suckers, or offshoots, is the pruning practice most commonly referred to, tomato plants also benefit from removing some leaves.
Many growers remove the bottom leaves of tomato plants as they grow to improve air circulation between tomato plants. The increased airflow limits stagnant, moist air–reducing the chance of disease among plants.
Ideally, remove at least a foot of the bottom-most tomato leaves, leaving the remaining leaves for photosynthesizing and providing shade for developing fruit.
Topping is the practice of trimming tomato vines, effectively rendering indeterminate tomatoes determinate. Most gardeners cut back tomatoes a month before the first fall frost, allowing green fruits on the plants time to ripen before the season’s end.
You can top tomatoes whenever you want to halt their growth – some growers top tomatoes once tomatoes have outgrown their trellis to make the plants more manageable.
Determinate & Indeterminate Types
All of your favorite tomato varieties fall into one of two categories – determinate or indeterminate:
- Determinate tomato plants grow until they reach a certain height, at which point the plants flower, bear fruit, and complete their life cycle.
- Indeterminate tomatoes will continue growing, flowering, and fruiting until the first killing frost of autumn.
Both determinate and indeterminate tomatoes benefit from some pruning, although pruning each type looks a little bit different. Read more about the differences between the two types here, and reference this article for a list of favorite determinate tomato varieties.
When To Prune Tomato Plants
Pruning tomato plants is an ongoing process that begins three to four weeks after tomatoes have been transplanted. Early summer is an ideal time to prune tomatoes – any earlier and risk pruning too hard, but wait any later and pruning will lose some of its effectiveness.
Start paying careful attention in late June and early July, as these are the months when tomatoes start flowering, which helps to differentiate suckers from fruit clusters. You’ll want to check in on your tomatoes every week after you notice the first suckers growing, and get in the habit of pruning early – after the morning dew has dried but well before the hottest part of the day.
Remove suckers before they get more than two inches long, as they’re easier to remove. At the same time, remove any discolored foliage or leaves at the base of the plant.
How To Identify Suckers
Tomato suckers are the tiny shoots that appear between the stem and leaves of the plant. If left alone, suckers will grow into fruit-producing vines.
Suckers draw energy away from the parent plant and can actually increase the risk of disease. Removing suckers improves the health of your tomato plants and makes them significantly easier to manage.
Suckers are branches or shoots that grow from the leaf axil or point where true leaves meet the main stem. Don’t confuse suckers with fruit clusters, which will have yellow flowers and show the beginnings of fruits.
How To Propagate Tomatoes Via Suckers
So you’ve pruned your tomato plants, but you hate to waste those suckers? No worries – you can propagate tomato plants with the leftover suckers! It’s so simple – just put your tomato suckers in a glass of clean water on a windowsill or sunroom – somewhere that gets bright indirect light.
Change out the water every few days, and give your science project some time – within two weeks your tomato cuttings will begin developing roots.
Once the roots are at least an inch long, pot the cuttings up in potting soil and begin gradually hardening the suckers off to outdoor temperatures and lighting conditions. After a week your tomato suckers will be ready to plant!
Note that propagating tomatoes via suckers is only really worthwhile early in the season, while the suckers still have time to mature. After a certain point in the season, tomato suckers won’t have time to grow into adult plants and bear fruit before the killing frost.
4 Essential Ways To Prune Tomato Plants
Pruning tomatoes isn’t difficult, but it does take consistency. Once you start seeing suckers on your tomatoes, you’ll want to check for suckers at least once a week.
Pruning Suckers (also called “suckering”)
Start With A Sanitized Tool
You can snap small suckers off with your fingers, but bigger suckers require a pair of snips or shears. Either way, wash your hands before pruning and sanitize your tools with a diluted hydrogen peroxide solution before you begin and in between plants, to avoid transferring diseases between plants.
Locate The Suckers
Check each joint where leaves meet the stem for suckers. The University of Wisconsin-Madison has a fantastic diagram and accompanying article illustrating how to locate and prune suckers:
“Identify the lowest flower/fruit cluster on the plant (i.e., the flower/fruit cluster closest to the ground). Remove every sucker from the plant EXCEPT for the first one below the lowest flower/fruit cluster. That sucker is the strongest one on the plant and should be left to grow and bear fruit as a second stem (Dampier).”
https://hort.extension.wisc.edu/articles/tomato-pruning/
Once you’ve found identified all the suckers, decide if you will leave any to create a multi-branched plant. Most growers leave one or two suckers on their tomato plants, resulting in two or three manageable fruit-producing vines. Multi-branched tomato plants aren’t difficult to maintain and moderately increase fruit yields and flavor.
Make A Clean Cut
Using a clean tool or your fingers, make a clean cut or break at the base of the sucker above the joint. Discard the suckers in a compost pile or root the suckers in water to propagate more tomatoes. The plant will quickly callous over the wound, healing itself and directing its energy elsewhere.
Pruning Fruit Clusters
Some growers choose to prune fruit clusters, insisting that pruning immature fruits makes the remaining fruits larger, and quicker to grow. This pruning phenomenon applies to most fruiting plants, but especially tomatoes, according to the Durham County Center of the NC Cooperative Extension:
“A plant will produce either fewer large tomatoes or more small tomatoes, so by removing ripening tomatoes from clusters, the plant is encouraged to redirect energy into the remaining tomatoes, making them larger (Troth).”
https://durham.ces.ncsu.edu/2020/06/pruning-for-healthier-more-productive-tomatoes/
Only prune fruit clusters that have six or more fruits, and remove no more than one-third of the cluster, or two fruits. Prune fruit clusters while the fruit is still green for the best results.
Pruning Foliage
Tomatoes really benefit from pruned foliage. Tomatoes are very susceptible to diseases, especially when the plants are planted too close together.
Promote better airflow and minimize disease by removing discolored leaves as you see them, and by removing the bottom foot or so of leaves from the plants. Prune foliage as often as you prune suckers–about once weekly.
Topping Tomato Plants
One final tomato pruning technique is called topping. Topping isn’t specific to tomatoes, and tomatoes don’t have to be topped, but some gardeners swear by the practice. Topping tomatoes is a one-time pruning task that takes place about four weeks before your area’s first fall frost.
Determinate tomatoes naturally stop growing once they reach a certain height, but some growers top indeterminate tomatoes a month before the first killing frost of autumn to encourage green tomatoes to ripen before the end of the season.
You can top tomatoes at any point that you decide you don’t want your tomatoes growing any taller. Some growers choose to top tomatoes when their plants begin to outgrow their trellis.
To top tomatoes, decide which fruit cluster you want to keep, and cut the tomato stem just above that fruit cluster. If you can, leave one or two leaves above the fruits to protect the clusters from sun damage.
Common Tomato Pruning Mistakes
Tomatoes are tough plants that can take some abuse, but be mindful of these common tomato pruning mistakes.
Over Pruning
Never remove more than a third of tomato foliage, or you risk seriously injuring the plant and damaging your harvests. Remove diseased foliage and foliage around the bottom of the plant, but leave the leaves above fruit clusters – the extra foliage helps protect fruits from getting burned by the sun.
If you cut a tomato leader – or the main growing tip – your tomato plant will not grow any taller – you have essentially topped the plant. If you’ve left a sucker or two on the stem, you can leave that sucker to become the new leader.
Moving Too Fast
Don’t rush pruning until it becomes second nature. Give yourself time, at least in the beginning, to really see and identify suckers from leaves, fruit clusters, and leaders. Any suckers that you miss will just become more difficult to remove with time.
Pruning Wet Plants
Tomatoes don’t like to stay wet, so avoid pruning tomatoes during rain or immediately after they’ve been watered. Wet foliage and soggy soil open the door for fungal diseases and bad bacteria.
Keep tomatoes as dry as possible by growing them under plastic or by using drip irrigation to water the plants at their base. Wait to prune tomatoes for a dry day, and keep tomato leaves and fruits from touching the ground.
Using Dirty Tools
Do not use dull or dirty tools to prune tomatoes! A surgeon would always use new or sanitized equipment for each patient, so do the same for your tomato plants.
Tomatoes are more likely to form a healthy callous if pruning cuts are made with clean, sharp tools. Disinfect your tools between tomato plants to minimize the spreading of disease between plants.
Pruning Determinate Varieties
Determinate tomatoes don’t really benefit from pruning – in fact, pruning determinate varieties may actually reduce potential yields since these varieties are designed to stop growing at a certain height.
Not Keeping A Consistent Schedule
Pruning is a continual process, not a one-and-done task! Keep a regular pruning schedule to stay on top of pruning. Make suckering part of your weekly gardening regimen and it won’t feel like such a daunting chore.
In Summary
Pruning tomatoes isn’t difficult, but it is a recurring task that can spell the difference between success and failure in the tomato patch. Removing young suckers results in larger and sweeter fruits while pruning excess foliage keeps tomato plants healthier all season long.
Top your tomatoes in late summer to hasten the last harvest of the year, and you’ll be a tomato-growing pro!
You can learn more about heirloom tomatoes (and how to grow them) here.
I hope you found this article helpful. If so, please share it with someone who can use the information.
If you want to read some of my most popular posts, please check out the “Best of GreenUpSide” page here. Enjoy!
~Jonathon
Resources
Daughtry, Minda, and Rhonda Gaster. “Try Pruning to Get Larger Tomatoes | North Carolina Cooperative Extension.” Lee County Center, 30 May 2018, https://lee.ces.ncsu.edu/2018/05/try-pruning-to-get-larger-tomatoes/. Accessed 17 May 2022.
Dampier, Jay. “Tomato Pruning – Wisconsin Horticulture.” Wisconsin Horticulture, 8 February 2021, https://hort.extension.wisc.edu/articles/tomato-pruning/. Accessed 17 May 2022.
Troth, Ashley. “Pruning for Healthier, More Productive Tomatoes | North Carolina Cooperative Extension.” Durham County Cooperative Extension, 11 June 2020, https://durham.ces.ncsu.edu/2020/06/pruning-for-healthier-more-productive-tomatoes/. Accessed 17 May 2022.
About the author:
When not writing content or growing flowers in her native Virginia, you can find Sarah hiking a long-distance trail deep in the woods. Follow along with Sarah’s adventures at http://sarahcolliecreative.com.
