Water thoroughly, then mulch heavily to try to even out the soil temperature and moisture.

The blossom cycle of tomatoes is about 3 weeks, so once the weather cools off, new blossoms that bloom should have no problem setting fruits.

Hope that helps.

Betsy

You mean I have to wait at least three weeks before the effects of the sudden hot spell will fade and so my plants can return to normal? NOOOOOOOOOOOO~ My poor plants. And the weather is on the fritz again, heating up and cooling, looks like it's gonna be a detrimental summer for my tomatoes. Sigh. Thanks for the help!

-Jenn

We had some pretty hot weather too, recently, and I read some advice on this forum to give the plants a good shaking to help them pollinate. I did that, and was lucky enough to have my blossoms set fruit even though the temps were up in the 90s. They didn't all set fruit, but almost half of them did (which was more than I thought). Maybe the shaking treatment will help with yours?

Shaking or what I call spanking the vines will help pollination. I spank my plants lightly with a stick early in the season and when it gets hot. 90 may be hot for some of you but it was 100 here with a heat index of 116 today. My plants have no problems producing up to 95 degrees but with todays temps they have probably stopped and I will be spanking them tomorrow and maybe through the next month and it's not even August yet which is our hottest month. BTW I mostly grow cherry, grape and pear varieties and have never experienced BER in those varieties. Keeping the soil evenly moist should take care of the BER but if not then you could have a shortage of calcium in the soil. Are they in ground or containers?

Were having the same weather here in Germany and I have been vibrating my flowers also to promote fruit set. Have had some blossom drop as well which can be expected but still getting fruit set. Get a cheapy battery powered toothbrush and use it to vibrate your flowers. Make sure you keep the moisture level on an even keel to help prevent BER. Last thing you want is the plant to get stressed, especially when dealing with high temperatures. Ami

I do shake them every morning when I water, but they're dropping a lot of unopened flowers, as well as opened ones, they're in containers. They seem to be having trouble setting flowers and fruits, as some just turn the whole truss of flowers yellow. But the weather cooled a little the last day and there is some fruit set among the cherries but the bigger ones just seem to kill all their blooms and even some that have started to set fruit turn yellow. Looks like I just have to wait for the weather's cooperation. Thanks for all the help, you guys are awesome!!

-Jenn

You also need to fertilize with a general purpose 10-10-10 or 12-12-12 etc. at least every 6 weeks. Fertilizing weekly with 1/4 strength is even better IME. Containers leach out the nutrients along with the water if your soil drains properly. You may also need to water every day and a very weak solution daily might not be a bad idea.

Hi jwwc,

The bloom (sexual) cycle for tomatoes is indeed 3 weeks. However, you may not have to wait that long for new blossoms to actually bloom.

I tried to find out one time at what point in the cycle heat can damage pollen (such as when the bud is 5 or 10 or 15 days old.) I didn't get an answer on that and got flamed so bad for not checking the FAQs that it still hurts when the sun gets hot and I have not tried to research it since to see if there is more info on that aspect of blossom drop since then. That was back in 2003, IIRC, the year we had 3 days at 110° and 10 over 100° in one month and my buds were dropping like crazy. I found at those temperatures, shaking, vibrating and spanking the plants had no effect on the blossom drop.

If the pollen in 10 day old buds is unaffected, you may only have to wait 11 or 12 days for buds with viable pollen.

Good luck!

Betsy