I wasted three growing seasons in my Brooklyn rowhouse backyard. Beautiful, leafy, six-foot-tall tomato plants every June. By August, maybe twelve actual tomatoes. I was ready to switch to growing only peppers.
The problem wasn’t the soil or the fertilizer. I was letting the plants grow completely wild. Every single branch was competing for the same limited supply of sugar and energy, so the plant focused on producing more leaves rather than growing fruit.
Then a retired farmer taught me how to prune tomato plants properly. Last summer, I pruned weekly—same four plants. Eighty-seven tomatoes harvested. Here is the exact five-minute weekly pruning method that changed everything.
Understanding Indeterminate vs Determinate
Before you start ripping leaves off, you need to know what kind of tomato you are growing.
Determinate tomatoes are bush varieties. They grow to a specific height, produce all their fruit at once, and then die. Do not prune determinate tomatoes. If you cut off their branches, you are just throwing away fruit.
Indeterminate tomatoes are vining varieties (like Cherry, Roma, or Beefsteak). They will keep growing like a weed until the frost kills them. These are the ones you must prune. If the seed packet or plant tag says “vining” or “indeterminate,” grab your scissors.
Step 1: Finding the Suckers
The entire secret to pruning is finding and removing the “suckers.”
Look closely at your tomato plant. You have the main vertical stem running straight up the middle. Coming off that main stem are horizontal branches with leaves on them. A sucker is the brand new, tiny shoot that grows right in the “V-joint” between the main stem and the leaf branch.
If you leave that tiny sucker alone, it will grow into a massive secondary main stem, complete with its own leaves and eventually its own flowers. That sounds good, but it’s actually terrible for container or small-space gardeners. The plant’s energy gets split too many ways.
Step 2: Pinching Them Off Early
The goal is to remove those suckers while they are still tiny.
Check your plants every single week. When the suckers are under two inches long, you don’t even need tools. Just grab the sucker between your thumb and pointer finger and snap it sideways. It will break off cleanly (your fingers will turn green and smell like tomatoes, which I secretly love).
If you miss a week and the sucker gets thicker than a pencil, don’t try to snap it. You might accidentally strip the skin down the main stem and invite disease. Use sharp bypass pruners to snip it off as close to the main stem as possible. Honestly, the cheap ones from the hardware store work just as well as the expensive brands.
That covers the top of the plant. Now let’s fix the bottom.
Step 3: Removing the Lower Leaves
Once your tomato plant is about three feet tall, look at the bottom foot of the main stem.
Those lowest leaves are usually resting directly on the dirt. When you water the plant, soil splashes up onto those leaves. This is exactly how soil-borne diseases like blight infect your entire plant.
Take your pruners and cut off every leaf branch on the bottom twelve inches of the stem. It looks ruthless, but it creates crucial airflow around the base of the plant (trust me on this one). Bare stems at the bottom mean healthier leaves at the top.
Step 4: The Late Summer Topping
This is the hardest rule to follow, but Joanna swears by it.
About four weeks before your first expected fall frost, you need to “top” the plant. Take your pruners and cut off the very top growing tip of the main stem. Yes, you are intentionally stunting the plant.
Why? Because any new flowers that bloom in late September won’t have time to grow into mature tomatoes before the frost hits anyway. By cutting off the top, you force the plant to stop growing vertically. All of its remaining energy gets redirected into ripening the green tomatoes that are already on the vine.
Wait, Don’t Make This Fatal Mistake
The biggest mistake I see beginners make is pruning their plants while they are soaking wet from rain or a sprinkler. Water acts like a highway for bacteria. If you create an open wound on the stem while it’s wet, disease will immediately set in. Wait until the afternoon when the sun has completely dried the leaves before you do your weekly pruning.
Once your tomatoes are pruned and thriving, you might want to look into 10 Tricks That Help You Harvest a Brag-Worthy Pile of Tomatoes to maximize their yield even further. Or, if you’re dealing with pests, check out 12 Plants to Grow Under Tomatoes to keep the bugs away naturally.