How to Prune Tomato Plants in 6 Easy Steps
Are you struggling to find the most efficient way of pruning your tomato plants this season? Tomato pruning can be a chore, but it doesn't have to be complicated. In this article, gardening expert and farm owner Jenna Rich walks through the six steps you'll need to follow when pruning your tomato plants this season.
I often hear people saying, “I let my tomatoes get away from me this summer,” or “I just don’t know how to control my tomatoes when I grow them, so I let them go wild.” There is nothing worse than putting a lot of hard work into growing a garden and then losing control of it!
Tomatoes are definitely a favorite crop to grow in the summer, but it can be hard to know how best to take care of them. Proper pruning will help you get maximum yields and keep your disease pressure down so you can enjoy fresh, juicy tomatoes all summer long. When you don’t know how to prune, or when to prune, pruning can be a tough thing to tackle.
When you don’t know how to do it, pruning can be a tough thing to tackle. However, it is a fairly simple process that just takes a few tools and a little bit of time. Here are six easy steps to keep your tomatoes in line.
Step 1: Get to Know Your Tomatoes
There are two different types of tomato plants; determinate and indeterminate. Each type of tomato is grown for different reasons. An important thing to note is that there is no real need to prune determinate tomatoes.
All of the fruit on these plants ripens all at the same time, all within a short time frame. They are often referred to as “bush tomatoes” because they only grow to be 4-5 feet tall. This type of tomato is ideal if you want to harvest all of your tomatoes at once in order to do lots of canning to have them available in the off-season.
There is little to no pruning necessary with determinate tomatoes because they stop growing once they set fruit. If you are not one who loves to be out in the garden once a week tying up tomatoes, this type might be for you.
These tomatoes set fruit all season. They will ripen beginning with the lower clusters and move up the stem. They will continue to grow as long as they are given something to climb up or trellis. These plants are sometimes called “vining tomatoes.”
Indeterminate plants are ideal if you want to have a little bit of fruit all season long instead of one heavy flush of fruit. Pruning and trellis or caging this type of tomato is very important to successful growing.
The next step in pruning plants is to collect the right tools. All tools should be sanitized and sharpened. This is important when pruning, as you are essentially damaging the plant, opening it up to certain diseases.
- Pruning shears
- A trellis system
- A bucket for clippings
Be sure to sanitize your pruners in between sessions and only prune dry plants to keep disease pressure down. The simplest and most cost-effective way I’ve found to keep your pruning shears disinfected is to spray and wipe them down in between uses with a 70-100% isopropyl alcohol. No mixing, soaking, or diluting is necessary.
Step 3: Prune Before Transplanting
Before transplanting your tomatoes, you should remove the lowermost leaves of the plant, leaving only the healthiest-looking ones. As a general rule, there should never be any leaves touching the ground.
Creating open space around the base of each plant is important for preventing fungal disease. Fungal disease can come into play when water splashes up from the soil onto the leaves of the plant. Doing this will help give your plants a great chance at staying disease free and to thrive.
When cutting off leaves, make sure to cut close to the main stem and not an inch or two out. You want the cut close and clean. Young plants are taking in the sun with the few leaves they have so just be sure to leave enough on for ample sun intake.
Once growth really takes off, you should walk through your tomatoes at least once a week, taking note of any spotting, curling leaves, yellowing, etc. This is also when you should be trellising your plants or guiding them up the string or cage. Your plants are looking to you for support so be sure you help them out!
Suckers grow between the main stem and each leaf, growing out of the space called the “axil.” They grow in an upward diagonal fashion, making them pretty easy to spot. This is the plant’s way of reproducing, which like all living creatures, is its main purpose of existence.
Identifying and snipping off suckers is a task that should start early and continue all season as they can take over quickly, making your plants unruly.
You should snip suckers right away as they will grow large, begin to flower, and set fruit causing competition for nutrients and resources which will make your tomato area hard to control.
When suckers are small, you can simply pinch them off with two fingers. Once suckers are as big around as a pencil, be sure to use sharp, clean snips to remove them as flush to the main stem as possible.
Some growers recommend leaving a few suckers around just in case you lose the main growing tip early on in the season. If this happens, simply re-train your plant so the sucker becomes the main leader.
If you want to get more bang for your buck, create a “double leader” system. Choose a strong sucker that is fairly low on the plant and train it up your trellis system. This will become your second “leader”. You’ll prune each of these leaders as if they are their own plant, essentially getting fruit of two plants from one!
Step 5: Prune to Create Space
One of the most important aspects of tomato pruning is to ensure your plants have enough airflow to prevent disease and ample space to grow.
Indeterminate tomatoes should be planted 12-24 inches apart for smaller varieties such as cherry and cocktail and 18-24 inches apart for larger varieties such as heirloom and beefsteak varieties.
If you decide to use a double leader system, you should plan on having a trellis system that allows enough space in between the two leaders. The two leaders should point up and out in opposite directions from the main stem and form the shape of a “Y.”
Tomato plants only need about ⅓ (6-7 leaves per plant) to grow. It is important to keep the bottom 6-12 inches of plants clear of leaves (especially yellowing ones), suckers, and debris. Any rainwater splashed up can quickly spread disease.
Deep watering is the best option for tomatoes (as opposed to overhead watering) as it promotes a strong and healthy root system and keeps splash potential to a minimum.
Step 6: Prune Throughout the Season
It’s important to be in the habit of walking through your tomatoes at least once a week, checking for disease and pests, and to harvest fruit. Remember to have your favorite pruning tool handy just in case you see a stray sucker or yellowing leaves.
On average, you’ll remove about 2-3 leaves per plant per week, depending on its growth, the weather, and the variety. Be sure to keep some leaf coverage for each cluster to avoid sunscald.
As the season progresses and fruit is being regularly harvested, you should remove empty trusses. A truss is a cluster of small stems from which flowers and fruit form and emerge. There is simply no need for these to be hanging out at the bottom of the stem once they have been emptied of fruit.
Many gardeners, especially ones growing in northern regions with shorter growing seasons will “top” their tomato plants around mid-late August.
This simply means cutting the growing tip off which stops the plant from producing new fruit, reallocating its energies to ripening fruit that is already on the plant. This allows you to take advantage of the remainder of summer and make sure all the fruit ripens.
Any disease present can be spread from dropped clippings, so be sure to keep the growing area tidy. Use a bucket to remove any pruned leaves and suckers from around your tomato plants and add to a burn pile.
Though these problems may be common, they are easily remedied. Don’t let these few problems stop you from snipping away at those little suckers on your tomato plants!
Why is it important to remove suckers and leaves?
Firstly, tomatoes will ripen sooner if you properly and regularly prune your plants so they can focus their energy on making fruit. When too much foliage is present, the plant has to spread out its resources to all parts, making it hard for it to know what’s important. You want to keep competition for resources down and help the plant know where it should focus its energy.
Secondly, pruning is extremely important in creating quality air control which keeps fungal disease pressure down.
An added bonus of clean, manicured plants is you can see everything that’s going on more clearly, and this includes pests. Hornworms are already very camouflage so having fewer leaves to poke through makes them easier to spot and them less to munch on!
Is it possible to over prune my tomato plants?
Simply put, yes. When plants are young, you want to ensure there is enough leaf surface area present for the plant to take in sunlight and make quality photosynthesis and growth possible.
As each plant grows, you want to ensure ripening fruit has enough leaf coverage to protect them from the sun and prevent sunscald. Too much pruning can cause stress, open up the risk of disease, shock, and even death.
What to do if you mistakenly cut off the main growing tip?
Earlier I described a double leader system and how some growers leave a few suckers around for this exact instance. If it’s early enough in the growing season, simply choose a sucker and train it up your trellis. This will become the new leader. If it’s closer to the end of the season, having the tip removed will simply reallocate the plant’s energy into ripening existing fruit.
Pruning your tomatoes is essential for maximum yields and low disease pressure. Read up on pruning now so that you are confident heading into your growing season. It can seem intimidating at first, but it’s not difficult once you get the hang of it!
Whether you say to-MAY-to or to-MAH-to, with proper pruning, your plants will thank you and you’ll thank yourself later when it comes time to enjoy the fruits of your labor.