The Sucker’s Guide to Pruning Tomatoes

I lost an entire summer to tomato jungle once. The plants were enormous, beautiful, incredibly leafy, and produced roughly fourteen tomatoes between the four of them. I was so proud of how big they got. That was dumb.

Turns out when you let an indeterminate tomato do whatever it wants, it wants to grow leaves. Not tomatoes. Leaves. The plant has opinions and they are wrong.

What a Sucker Actually Is

Look at where a branch meets the main stem. See that little shoot growing up at a 45-degree angle right in that crotch? That’s a sucker. Left alone it becomes a full branch, which grows its own suckers, which grow their own suckers, and by August you have a seven-foot green monster held together with twine and regret.

Every sucker you let go is the plant putting energy into structure instead of fruit. Which, now that I think about it, is exactly the wrong direction in July.

Indeterminate Only. This Matters.

Before you go snapping things off, check what you’re growing. Indeterminate varieties keep growing and setting fruit all season. Think Sungold, Early Girl, most heirlooms. Those are the ones you prune.

Determinate varieties are bred to grow to a fixed size, set fruit all at once, and stop. You prune those and you’re just removing future tomatoes. I made this mistake with a Roma plant in 2019 and told nobody about it until just now.

How to Do It (for Free, With Your Fingers)

Small suckers, under an inch or so, just pinch them off with two fingers. Done. No tools, no cost. The wound is tiny and heals fast.

Bigger suckers, ones you let go for a week because you got distracted, you’ll want a clean pair of pruning snips. Cut close to the main stem but don’t dig into it. And if you’re going plant to plant, wipe the blade between cuts. Tomatoes can pass disease on a dirty blade faster than my kids share a cold.

Do this in the morning if you can. The cuts seal better when the plant isn’t heat-stressed. I read that somewhere, tested it exactly once, and now I repeat it like I’m an expert.

The One Sucker You Leave Alone

The sucker right below the first flower cluster. Some people call it the leader sucker. Leave that one. It becomes your second main stem and that’s actually a good thing on indeterminate plants. Two stems, one plant, more fruit. I run most of mine as two-stem plants and it works well in our Redmond summers where we’re racing to get fruit before October clouds move back in.

Everything else above that? Gone.

How Often

Once a week is about right. In July heat, suckers can go from tiny to enormous in five days. I do a walk-through every Sunday morning with coffee and just pinch as I go. Takes maybe ten minutes for six plants. Satisfying in a slightly violent way.

If you miss a week and come back to suckers the size of your thumb, just cut them. Yes, the wounds are bigger. The plant will survive. I ignored my garden for two full weeks during a camping trip and came back to absolute chaos, and the plants still made tomatoes. Annoyingly resilient, given how many ways I’ve tried to accidentally kill them.

Does It Actually Work

Last year I ran a totally unscientific experiment. Two Sungold plants from Sky Nursery, same spot in the bed, started the same week. One I pruned weekly. One I ignored completely as a control group. That’s what I told myself, anyway.

The pruned plant had ripe fruit about eight days earlier and stayed productive through mid-October. The unpruned one was a tangled mess by August, set a ton of green tomatoes in September that never ripened before the cold hit, and my daughters thought it looked cooler because it was bigger. They are not wrong about the aesthetic. They are wrong about the tomatoes.

So. Pruning works. It’s free. It takes ten minutes a week. And the only thing you’re losing is a bunch of leaves that were freeloading anyway. Stems above their station, really.

You could say those suckers were really just suck-ers all along. (I’m not sorry.)

Photo by Sarah Damen on Unsplash