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"Pruning Tomatoes": Who's the 'Sucker' Here?


Q. Can you please explain which shoots on a tomato plant should be pinched off so that the strength of the plant goes into maximum fruit production?
    ---Miriam in Lower Gwynedd, PA
Should some of the shoots on tomato plants that develop between the main stem and leaf branches be pruned?
    ---David Walzer; Penn Valley, Pa.
A. No, I don't believe that they should be. There is an abundance of advice out there suggesting that selective removal of "suckers" will improve the health and vigor of a tomato plant, but this flies in the face of basic horticultural physics.

Plant leaves are essentially solar panels; via photosynthesis they turn sunlight into energy that the plant can use. The more leaves, the more potential energy to fuel the growth of the plant and its fruits—and to enhance the complex flavors inside those fruits. (This is why some classic heirloom varieties like Brandywine have a tendency to produce more leaf matter and fewer fruits than other varieties—the incredibly complex flavor components in these supremely tasty love apples simply need more energy to develop.) Removing healthy leaves to get bigger fruits is like taking half the solar panels off your roof to get more power—it just don't work that way.

And it's especially important not to remove any healthy leaves if your tomato plants get full sun all day. They need every possible leaf to shade their fruits and protect them from sun scald—essentially a kind of fruit sunburn. The actual fruits of a plant can't process solar energy; only the leaves can do that. And having lots of leaves is great protection for plants in very hot and sunny locations. (This is why the common advice to 'ripen green tomatoes on a sunny windowsill' is equally bogus; all that sun is doing is cooking away flavor. If its fully grown, a green tomato will ripen in total darkness!)

Q. I have several different varieties of indeterminate tomatoes. They appear to be very healthy and rigorous as of late June, and that's my problem. The leaf and stem production is causing crowding, even though I spaced them about 18 inches apart. Can I prune them now without significantly damaging overall fruit production?
    ---Paul; Wilmington, Delaware
A. I just looked at the big ruler I keep in my office and decided that 18 inches between plants is like a professional basketball player sleeping in a twin bed; and the player is NOT Allen Iverson. Eighteen inches between the EDGES of FULLY GROWN plants is more like it, Paul. That's one of the many things I like about tomato cages; they help you keep the final edges of the plants well defined, even back when you're putting teeny tiny baby plants in the ground.

If you have room, transplant the one in the middle to another spot. Do this in the evening, NOT the morning, try and get most of the roots to stay inside a big island of soil and let a hose drip at the base of the plant overnight afterwards. This will also allow you to cage the plants if you haven't already.

Q. I have a very small plot and this year only planted three tomatoes. Last year they grew so much the vines were trying to cling to a small tree at the back of the plot. I got lots of tomatoes, but they didn't ripen or grow to the expected size. It is advisable to (dare I say it) prune the plants to control them?
    ---Dan in Drexel Hill, Pa.
A. Sounds like your puny green produce was the result of too many tomatoes for the space; and growing those plants too close to the nutrient-stealing roots and shade of a tree. You'll get more and better quality tomatoes from one plant that has lots of room than from three struggler. Move a few to other spots or find a good home for them (again—move and replant in the evening) and concentrate on giving one plant what it needs.

Q. I have your book "You Bet Your Tomatoes" and know the importance of giving them lots of breathing room when planting, using REAL cages, compost for disease control, etc., etc.; but I don't know how you feel about pruning. Last year, the plants grew really vigorously and the foliage became so dense they weren't getting good airflow. About mid season, the leaves started turning yellowish brown and withering. I did start pruning at that point, but took a bad hit on my yields. How would you handle this? Thanks.
    ---Chip down in Waco, TX
A. As I've been belaboring, lots of room at planting time don't mean much. They're cute little puppies then; not the 14-foot long monster vines they will soon grow to be (unless you kill them first, of course). So to belabor redundantly (once again): Plan for the final size! Grow small herbs or flowers down below so you don't waste any space, but double the distance between your tamata plants next season.

For THIS season, some pruning might make sense. All tomatoes get discolored leaves at some point and it is an excellent idea on all levels to remove those leaves as soon as you see them. If it's been really wet and the plants are crowded, remove entire branches that have rogue leaves on them. The adjoining leaves are probably already infected, and getting them out early while also increasing the interior airflow will do wonders for the future.

But more space next year! I planted fewer tomatoes this season, and it's already pretty obvious I'm going to get a much bigger harvest than I did with lots more plants....

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