90+ degrees and my tomatoes are flowering

sandpapertongue(7a VA)June 17, 2014

This is my first year growing tomatoes and it's crazy how much I am enjoying it. Watching my plants grow is like being a proud parent -- "Almost 3 feet tall now! And look at all these fruits forming!"

I have 2 Lemon Pears (I bought them without research and have since discovered that on Gardenweb, they are pretty much universally despised) that have been flowering and forming tomatoes beautifully. I also have other plants (Black Cherry, Ponderosa) that I grew from seed and are growing nicely, but I started late and they don't have any flowers yet.

We have had great weather up to now, but this week we are looking at 5 days in the 90s, possibly getting up to 97 degrees tomorrow. So what does this mean? I know that when it's over 92 degrees, the flowers won't be able to pollinate, so all those unpollinated flowers right now won't be able to form fruit. But does that mean when it cools down again, the tomato plant will go back to producing fruit? Or does the plant switch modes and focuses on ripening the existing fruit?

Basically I asking, is my Lemon Pear production going to be done once the weather is hot, and is it hopeless for my not-yet-flowering plants to ever get fruit?

Our summers are usually hot, with several days over 90 degrees but we have had Julys and Augusts with weeks in the 80s too. I thought I was in zone 7a, but it might actually be 6b if it makes any difference.

Thanks in advance for dealing with all these questions from a newbie!

The Lemon Pear

Growing fruits

Each plant has 5-6 flower clusters right now

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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Yellow Pear ;), not Lemon Pear.

So what does this mean? I know that when it's over 92 degrees, the flowers won't be able to pollinate, so all those unpollinated flowers right now won't be able to form fruit. But does that mean when it cools down again, the tomato plant will go back to producing fruit? Or does the plant switch modes and focuses on ripening the existing fruit?

It isn't quite as simple as 92 or either/or. It is a combination of factors of high temps with or without high humidity or lower temps plus high humidity. But the general guideline is 95 degrees plus high humidity = no fruit set. And it isn't just the temp on your outdoor thermometer but the actual temp in and around the plant itself which is often very different. Breezes make a difference, shade makes a difference, and night time cool downs make a difference, etc.

The blooms you already have are likely already pollinated as many are pollinated before they even open. If not you can help them by finger flicking the bloom cluster. And yes when it cools down again, even if it is weeks from now, it will bloom more and set fruit as long as the plant stays healthy.

Dave

    Bookmark   June 17, 2014 at 11:34AM
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sandpapertongue(7a VA)

Thank you Dave! As always, your explanations are indepth and so illuminating!

So, I have another question: if tomato plants will continue to flower and set fruit once the weather turns cooler again, then why do people do a fall planting? Is it because by August the plants are 10 feet tall and ravaged by pests and disease?

(Ah, yellow pear, not lemon. I think I gave them a fancier name in my head to make up for the lackluster reviews on this forum!)

    Bookmark   June 17, 2014 at 12:46PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

then why do people do a fall planting? Is it because by August the plants are 10 feet tall and ravaged by pests and disease?

Amount and type of care will determine the health of the plant when the cooler season arrives. Some prefer to just rip out the older plants and replace with new ones if their season length allows. Less work. And with determinate varieties not much is gained by trying to keep them going.

But with indeterminate varieties or in shorter growing seasons, it can be worth the effort to keep the plant well-fed, watered, affected foliage removed, damaged branches trimmed, and healthy until the weather breaks.

Some will trim the plant back to trigger new growth, many will take cuttings from the existing plant and root them. Lots of ways to insure a later crop.

Basically it boils down to your choice.

Dave

    Bookmark   June 17, 2014 at 1:18PM
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centexan254 zone 8 Temple, Tx

Dave is spot on. There are a few tomato plants in my garden that once the ripe fruit is harvested I will rip out. I will then plant fresh plants there. The ones that are being removed are dying off from producing fruit, and the heat is taking its toll as well. Not to mention some issues of blight. While the plants would survive, and maybe spring back a little. The output they would give once the weather cools here pales in comparison to plant that is more healthy.

Also production of new fruit takes a nose dive for most of the larger fruiting plants here this time of year for a couple of months due to the high heat, and humidity. A fresh plant will grow very large though that weather. It takes the cooling off to get fruit production going.

Oh and in my experience cherry varieties tend to be able to set fruit when the larger varieties shut down. The trade off is they seem to take a long time to ripen in the heat though.

    Bookmark   June 17, 2014 at 3:57PM
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