Sucker Punch: Why I Finally Started Pruning My Tomatoes (And What Happened)

I grew tomatoes for four years without touching them. Just let them do whatever they wanted. Full chaos mode, sprawling out of the cage by August like they were actively trying to escape. My neighbor finally walked over one day, looked at my plants, looked at me, and said “are you pruning those?” The answer was no. Clearly no.

Turns out I’d been growing a lot of very happy tomato plant and not a lot of tomatoes. There’s a difference.

What a Sucker Actually Is

Look at your tomato plant right now. Find where a branch meets the main stem. See that little shoot poking out of the V between them? That’s a sucker. Left alone, it becomes a whole new branch, which grows its own suckers, which grow their own suckers. You end up with a tomato bush the size of a small car.

The plant isn’t being lazy. It’s doing exactly what it wants to do. You’re the one with opinions about tomatoes.

This Only Matters for Indeterminate Varieties

Worth saying clearly: if you’re growing a determinate variety like Roma or Glacier, skip this. Determinates are bred to grow to a fixed size, set fruit, and stop. You prune those and you’re just removing future tomatoes. Not great.

Indeterminate varieties, most of the good ones honestly, just keep growing all season. Sungold, Big Beef, Early Girl, most heirlooms. These are the ones that will absolutely take over your raised bed if you don’t make some decisions. We’ve got maybe six to eight more weeks of decent ripening weather here in Redmond before things get dicey, so what the plant does right now actually matters. The clock is ticking and the plant does not care.

The Basic Move

Find the sucker. Pinch it off with your fingers if it’s small, under about an inch. Bigger than that, use clean scissors or pruners. I use a pair of Fiskars I’ve had since 2019 that I wipe down with rubbing alcohol between plants, mostly because I read once that you should and now I can’t stop doing it.

The goal for most home gardeners is to keep one or two main stems. One stem is more aggressive and works great if you’re growing in a tight space or up a string. Two stems gives you a little more production with still-manageable growth. Three or more and you’re basically back to chaos mode, just with extra steps.

I keep two stems on most of mine. Pick the main stem and the first strong sucker that grows below the first flower cluster. Let that one become your second leader. Everything else that shows up after that gets the pinch.

Why Bother

Fewer stems means the plant puts energy into fruit instead of leaves. Tomatoes ripen faster, grow bigger, and actually get enough airflow to dry out between rains. Which, this being July in the Pacific Northwest, still happen more than you’d think. Less foliage also means less late blight risk, and late blight is a real and genuinely annoying thing here in zone 8b.

Also your cage or trellis doesn’t turn into a structural engineering problem by mid-August. So there’s that.

The Part Where I Messed Up

First year I tried this, I got a little too enthusiastic. Took off basically everything I could find, including a couple of what I thought were suckers but were actually legitimate fruiting branches. One plant looked like I’d had a personal disagreement with it. It recovered, but things were weird between us for a while.

The fix: if you’re not sure whether something is a sucker or a branch, give it a few days. Suckers come out of the V. Branches come from the main stem and usually already have a little more structure to them. When in doubt, wait. You can always remove it later. You cannot put it back.

One More Thing for July Specifically

Around now I also start thinking about topping the plant, which means cutting off the very top growing tip. You don’t have to do this, but with our first average frost somewhere around mid-October, any flowers that show up after early August are probably not going to make it to ripe tomatoes. Cutting the top tells the plant to stop spending energy on new growth and focus on finishing what’s already there.

I usually top mine around the first week of August. Not a hard rule. Just what works in Redmond.

Anyway. Go check your tomatoes. Look for the suckers. Pinch the small ones off right now while you’re out there, before they get any bigger ideas.

The plants will thank you. Well, they won’t. But the tomatoes will. Which is kind of the whole point, and honestly the better deal.

Photo by Laura España on Unsplash