Effects of prolonged heat

elight(9b)July 21, 2011

This is my first year growing and needless to say, I've learned so much every step of the way (that unfortunately I have to wait 9 months before putting into practice). So now it's time for another lesson... Much of the country is experiencing extreme heat right now. I feel lucky to be in southeastern NY where temperatures have stayed under 100.

What are the effects of severe, prolonged heat on plants like tomatoes? What can be done to mitigate them? Should plants be moved to the shade at some point (or even indoors)? What if that's not possible?

Looking forward to your responses.

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missingtheobvious(Blue Ridge 7a)

I remember reading that people who grow in really inhospitably hot climates use shade cloth canopies over their tomatoes. Unfortunately I don't remember any details. Try searching the forum for "shade cloth" and "shadecloth."

    Bookmark   July 22, 2011 at 1:00AM
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Bets(z6A S ID)

Prolonged temperatures of 95 degrees and higher can denature pollen making it sterile so that flowers that bloom will not be fertilized, resulting in blossom drop. Anything that can lower the temperature in a given area can help, especially shading the plants with shade cloth as missingtheobvious has said.


Here is a link that might be useful: "Blossom Drop" FAQ

    Bookmark   July 22, 2011 at 6:01PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Prolonged heat also slows ripening or stops it all together until the weather breaks. You can even get fruit cooked from the inside out - boiled in the peel so to speak - if it gets really hot enough - 109 here today.

    Bookmark   July 22, 2011 at 7:41PM
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I thought our tomatoes would stall because we're having a heat wave (Southeastern Indiana) but we haven't had any blossom drop. It seems the tomatoes are enjoying the sauna-like weather. The only problem is, they're growing like mad and I can't bear to go out to tie them up. :)

    Bookmark   July 22, 2011 at 8:48PM
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I was also wondering the effects of the heat on ripening and going from 90 degrees at night to 50 in 48 hours. I'm expecting some mushy tomatoes by the time they finally ripen. I hope I'm wrong.

    Bookmark   July 25, 2011 at 11:12AM
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i live here in phoenix where 100 is a cool day in the summer the effects are what was mentioned above along with cracking some plants do far better then others my black prince and german queens are all dried up and dead yet my yellow cherries and bonnie grapes look ok. i don't think you guys will have prolonged heat like we do so it's probably no big deal. some people here shade them and mist them and stuff like that but i just keep on an even watering schedule to prvent cracking and they seem to pull through.....

    Bookmark   July 25, 2011 at 2:28PM
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It's been in the high 90's for, well, seems like forever here, though I guess it is only two-three weeks or so. No rain. I've kept some of my garden alive, including the tomatoes, by watering. I'm not really set up well for irrigation because for the last several years we've had sufficient or even excessive rainfall. I'm also not set up with shade cloth. I am seeing the delay in ripening and sunscald. I've got some plants that are still bushy enough to protect the fruit from sunscald, but several were hit with wilt of one kind or another. I have many nice green tomatoes, but the only ones ripening are the Joe Lauerer German eggs and a few of the Juliet and Black cherries.

I guess if I plan to continue my hobby gardening I'll have to plan for these years and collect some shade cloth and a reasonable way to set it up, as well as standby irrigation. I already have to grow behind a significant fence to keep the deer and coons out, so what's another few layers of stuff to deal with?

On the plus side, some of my best looking tomatoes are growing in two small raised beds I created instantly from pure aged horse manure I can get in unlimited amounts. After I had filled my original beds I was left with several seedlings I couldn't find a home for, and a friend was offering the horse manure. So, instant raised beds for which I had no real expectation of good results may end up giving me my best tomatoes.


    Bookmark   July 25, 2011 at 4:27PM
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Chuck60 - How do you like the Joe Lauerers? Linda

    Bookmark   July 26, 2011 at 1:46PM
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NW of DFW, Texas. Having ok luck w/Cherry tomato and yellow-pear tomato. All other, mostly heirloom are suffering big-time. Few blooms and very few tomatoes, like "3" :( We've had 27days of temps over 100 to 106 and NO rain for about 6wks. I'm new at this, don't plan to give up, keeping them watered, though scalding, wilt and lots of brown leaves, especially bottom halves. As long as stems are green, I'm hoping for revitalization once temps come down to mid-90s. I grew tomatoes into January last year, w/coverings and xmas tree lights. I could of kept it up, but, figured it all an experiment, w/temps falling to 6 and 7 degrees and 1/2 the winter below freezing. Proof it can be done. Now, it's the extreme heat for too many days. I'm hoping for the best though!

    Bookmark   July 28, 2011 at 2:20PM
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The main effect of very high temps is that plants tend to stop producing tomatoes--temps here have been 98-107 for about a month and I'm still picking a few ripe tomatoes, but I'm not seeing a lot of new ones.

Also extreme heat/dryness encourages spider mites, which I'm also dealing with. Probably about 2/3 of the leaves on my plants are dead but I'm hoping they can survive the heat and produce a little more this fall.

    Bookmark   July 29, 2011 at 11:15AM
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I'm beginning to love them, if only because they keep coming ripe while most of the rest of my ten or so varieties are just staying green. They at least taste like tomatoes, though they aren't particularly flavorful IMHO. I'll probably grow them again next year, hoping to have a better year to see if they are better.

I'm getting a very few Black Cherries and Juliets, and I picked a couple of Terhunes yesterday that were getting ripe and were too exposed to the sun for my liking. I've had a few Paul Robesons that looked like those flat peaches, Saturns? The small amount of good flesh on those tasted OK. Some Opalkas I picked when they were beginning to pink up turned out to be mainly pith inside. If the heat diminishes in a few days and we get some rain maybe some of my 50 plants will revive, but so far this is turning out to be even worse than last year, which was so wet all my tomatoes got wilt.

One good growing season would sure be nice.


    Bookmark   July 29, 2011 at 12:50PM
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