top of page

Pruning Tomato Plants

Happy Sunshine Gardeners!

Wow, what a HOT few days we've had in Portland. 97 on Tuesday and 99 on Wednesday. I swear my tomato and cucumber plants doubled in size overnight. They were loving these sizzling summer temperatures. I, however, was hanging out at home and the movie theater, comfortable in the air conditioning. I hope that you have stayed cool, well hydrated, and healthy.

I get many questions from gardeners about pruning tomato plants. We were discussing it in last weekend's Troubleshooting the Organic Vegetable Garden class at Portland Nursery. So yesterday morning while watering the garden I snapped a couple of photos I hope will help you.

I recommend pinching all suckers off of tomato plants. You locate these suckers in between the main trunk/stem and the branches. When they are small like this you can easily pinch them off with your fingers. If they have developed into stems, it is too late and just leave them be.

This is the "sucker" to pinch off your tomato plants

Tomato plants are monsters that will grow and grow and grow until a frost kills them in the fall. The problem specific to our mild maritime climate here in Portland, and the greater PNW region, is that our summer is short and mild.

While we do have a few really hot days, our July & August average high is 80 and average low is 58. In this shorter growing season with milder temperatures we need our tomato plants to produce fruit that will actually ripen by autumn.

When we pinch off the suckers this discourages excessive leafy green plant growth and for fruit to develop on the remaining branches.

As you know from my other posts and classes, tomatoes are a warm season vegetable crop that thrives in the hot weather of summer. You can read my Indispensible Guide to Growing Tomatoes in Portland here.

Tomatoes should be planted in the garden from seedlings/transplants when night temperatures are consistently above 55 degrees. In Portland this is typically May 15-June 1. Planting early without protection does not give you a jump-start. Tomato plants exposed to night temperatures below 55 degrees will cause stunting. Typically stunted plants will not recover and grow into healthy plants.

This year we did not achieve night temperatures consistently above 55 degrees until June 10. And that is pushing it a little late to plant tomatoes.

You can plant your tomatoes in early May when night temperatures are still cool with the assistance of season extenders like water-filled cloches. These are sometimes sold under the brand names Wall of Water and Kozy Coat.

While visiting a local community garden I spied this simple and inexpensive season extender for tomatoes. The gardener fastened greenhouse plastic around the tomato cage and secured with binder clips. The tomato plants inside looked super healthy and big.

When you purchase your tomato plants, or if you started your own inside from seed in January, you do not want the small plants to have flowers or fruit on them at planting time. We want tomato plants to produce lots of leafy green growth on strong plants for their first month. If they are flowering and fruiting when small the plant's energy is sunk into making fruit at the expense of plant growth. This will result in small plants with less tomatoes.

'Sungold' Cherry Tomato Plant 1 Month in Garden

For the first month tomatoes are growing in the garden, I am pinching off suckers and any flowers.

After one month this is what my tomato plant looks like. Nice strong central trunk/stem with moderate amount of branches, lots of healthy green leaves, and the now flowers. Leaves show no sign of cold damage.

This kind of pinching and pruning promotes as strong healthy plant with good air circulation.

Notice I have put the tomato cage around the plant at planting time and as it grows I am gently placing the stems in the cage for support.

Tomatoes are very successful in Portland gardens if you plant in a full sun location well-amended with compost, choose shorter season varieties, plant them at the appropriate time, give them consistent watering, provide monthly organic granular fertilizer, pinch/prune the plants, and keep them supported with a cage or other structure. Please let me know if you have any questions.

Happy Gardening,


'Lemon Boy' Tomato Plant 1 Month in the Garden

129 views0 comments

Recent Posts

See All
bottom of page