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Pruning Tall Tomato Plants

Posted by mewhee 9 (My Page) on
Mon, Mar 29, 10 at 10:38

Hi All -

O.K., I know, I know it's just the beginning of the season. My transplants here in So. Cal just went in last week but thought I'd hopefully get some feedback in advance from all you tomato growers and what works for you re: late season pruning.

My question is, it seems year after year towards the end of the growing season (late Aug./Sept.) I wind up with 8 to 10 ft. tall indeterminate tomato plants, both heirlooms and hybrids, of which the top 1/3 is quite lush with foliage AND some blossoms but they wind up producing very little in the way of fruit. Would I be better off to start pruning the tops say in August, thus allowing more production into the lower 2/3rds of the plant or continue letting them grow as high as they want?

Any suggestions?

Will and the Furry Ones

Follow-Up Postings:

RE: Pruning Tall Tomato Plants

Great question, the same thing happens to me in New Jersey

RE: Pruning Tall Tomato Plants

Often discussed but I don't know if any of the previous discussion are still available via search or not. Search 'pinching', 'pruning tops', 'plants too tall', etc.

So just my opinion - no, since it defeats the whole purpose of growing indeterminate varieties that are just doing what comes naturally to them. Nothing says you have to stake them to 10-12' tall and very few folks do so with no problems. But if you want short plants, grow determinates or so-called semi-indeterminates. ;)

thus allowing more production into the lower 2/3rds of the plant

You are assuming that would happen - new growth and even production in the lower 2/3 of the plant but it really doesn't or only does so minimally as that isn't the nature of indeterminate vines. The circulation to those lower branches has already been sealed off from the plant circulatory system.

Some varieties will send up new growth from the root ball if severely pruned back to within 1-2 feet of the ground and if the weather allows. But unless you have an exceptionally long growing season - and you may in zone 9 (but not in NJ) it doesn't have time to bear fruit. So what production you would have had otherwise is lost (assuming weather even allows for pollination.)

Like I said - JMO.


RE: Pruning Tall Tomato Plants

I have pinched new growth back starting 5-6 weeks before frost. That is the latest any fruits can ripen from new flowers. The initial immature leaves grow out (adding a foot or so to the plant) leaving the rest of the nutrients to go to the fruit rather than new grow. I have not compared flavor or fruit size to non topped plants, but it made my garden less messy with over grown plants and reduced the problem of end of year green fruit.

RE: Pruning Tall Tomato Plants

I've only trimmed tomatoes that got too tall upstairs or too leggy this winter in the GH. But I do it early before they start blooming.


RE: Pruning Tall Tomato Plants

FWIW, I attended a talk by a professional organic gardener. She said that topping off indeterminant tomato plants late in the season stops them from growing and producing more flowers/fruit, and redirects the plant's energy to ripening the existing fruit. If you're at a point in the season where new fruit is not likely to ripen, it makes sense (to me) to top off the tomato plant to increase the likelihood that the fruit on the rest of the plant will ripen.

Of course this does stop the plant from growing so it's not something you would ever do early in the season.

RE: Pruning Tall Tomato Plants

" Of course this does stop the plant from growing so it's not something you would ever do early in the season "

Topping plants early in the season does not stop new growth. In fact it may get twice the amount of new growth from suckers.

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