Pruning some tomato varieties can produce more fruit

For most people, growing tomatoes doesn’t get any more complicated than buying a $3 plant and plunking it in a sunny spot.

But there is one more thing that helps tomatoes grow bigger and keeps the plant healthier: pruning.

I know, it sounds a bit fussy. But in this climate, gardeners need to give tomatoes all the advantages they can. And it’s not hard. Really.

Here’s the science behind it.

Many tomato varieties are South American vines that will keep pumping out fruit until disease or the weather knocks them out. Suckers develop from the main stem and some of those suckers will eventually produce flowers and then fruit.

By pinching out some of those suckers, gardeners can redirect the plant’s energy into growing fruit that remains. Removing some side shoots not only increases the plant’s productivity but also allows for better light and air circulation, which will help prevent pest problems and disease.

A team of Snohomish County Master Gardeners has used pruning on some of the 5,000 tomato plants they grow annually for the group’s plant sale and for trying new techniques.

Master gardener Jeff Thompson — also known as “Mr. Tomato” — said from his unscientific observations, pruning the plants grows bigger fruit and more of it.

In his own Edmonds garden, he grows about 35 tomato plants outside, each in its own large black nursery container. He prunes his tomatoes about once a week.

Here are his tips:

Figure out the type of tomato: Pruning is only effective on vinelike tomatoes called indeterminates. Figure that out by reading the tag that comes with the plant. Some common indeterminate types are Early Girl, Sun Gold and Stupice.

Find the side shoots: The suckers grow in the “V” between the main stem and a branch. Pinch them off with your fingers. Start at the top of the plant. Find the first cluster of yellow flowers or small tomatoes and remove the feathery sucker growing just beneath.

Remove any dead, yellowing leaves toward the bottom of the plant. As the plant matures, the leaves toward the bottom naturally wilt. Clear them away, too. Ideally, the plant should be supported and present all its leaves to the sun.

Don’t yank all the leaves: Some people believe removing leaves helps tomatoes ripen faster. That’s not true. In fact, tomatoes need leaves to turn sunlight into sugar.

Remove all but one or two tomatoes from each fruiting group. If you remove some of the smaller, green tomatoes, the plant can put its energy toward what’s left. This is a good technique for larger fruited types such as Early Girl, Legend and Stupice, but not for cherry types that have a cluster of tomatoes, such as Sungold, Sweet 100 and Yellow Pear.

“It’s hard, sort of like having to choose your two favorite toys, but in the end you are rewarded with larger fruit,” Thompson said.

Indeterminate tomatoes should be staked or supported. Thompson makes his own round cages from rolls of concrete-reinforcing wire. Also try attaching the main stem of the plant to a bamboo shoot by looping a twist-tie into a figure eight.

A third option is training the tomato up a long, vertical piece of twine, attaching the main stem with tomato trellis clips, available at professional garden supply stores such as Steuber Distributing Co. in Snohomish.

Debra Smith: 425-339-3197 or dsmith@heraldnet.com