Heat and Harvesting
 

We're in the midst of a heat spell (as are many others in the country!) with temps up to 110 degrees for a few days and around 100 degrees for days beyond that /puke. I've got tomatoes ripening on the vine right now and it dawned on me that they might "cook on the vine" :?!?: in this weather (even though they are under shade cloth so a bit cooler). I did a brief web search on heat and tomatoes and came up with a site that says tomatoes stop ripening at 85 degrees and recommends harvesting at blush. I think could be a while before we get back down to 85 degree days). Specifically it says:

The optimal temperature range for tomato ripening is 68°F to 77°F (20-25°C); tomato ripening is slowed when temperatures are cooler or warmer than the optimum range. Tomatoes stop ripening when temperatures are less than 55°F (13°C)and greater than 85°F (29°C). Once a mature green tomato has begun to blush or turn color, it can be brought to full color or full ripeness off the vine at room temperature–70°F to 75°F (21-24°C).

Is this correct, and given the weather, should I go ahead and pick my tomatoes early? (I know you can harvest at blush and ripen indoors but I prefer to keep them on the vine as long as possible). How long can tomatoes stay at high temperatures on the vine before quality is affected?

Maybe the answer is "it all depends," but thought I'd ask anyway :).

Anne

I would definitely pick all blushing fruit before the heat affects the quality negatively.
I hope the damage is not already happening perhaps the shade cloth is helping.

Thanks so much, Karen, for the definitive answer!! I went ahead and picked another Pink Passion, my first Purple Heart, and a few Mt. Gems. The article I read also said that by removing the blush tomatoes that aren't going to get any riper on the vine due to the heat, the plant can devote more energy towards other things so you could get overall better yields :?!?:.

I'm sort of amazed that the plants are continuing to blossom and set fruit in this weather - but maybe there will be a delayed reaction down the line on that. The shade cloth does help a lot with the heat, though. Before it got too hot this morning, I managed to get up a bit of shade cloth over the bed for my corn that really needs to be transplanted soon.

My 3 kratky cucumber plants are going through about 8-10 gallons of nutrient water a day right now, but they're cranking out the cukes that are so refreshing in this weather.

The weather's so bad all over the states it seems, I wonder how others are faring. Hope everyone's managing to stay cool (or dry as the case may be).

Anne

I had that problem last year with indigo blue beauty.
It was a catch22,they need to be in full sun to turn blue but they ended up cooking.

I wrongly assumed that tomatoes would ripen faster the hotter it got for a long time. Years ago we had a freaky May with some of the hottest temps I have seen down here. We hit around 105 each day for nearly a week and it was preceded by two weeks of temps near 100 each day and followed by the same for much of that summer. It seemed like it took forever for any tomatoes to ripen. It was so hot and dry that birds and squirrels kept pecking and eating the slowly ripening fruit. I started picking them at first blush and moving them to the cooler shade of the porch at first blush and found they ripened faster than on the vine and with the added benefit of saving them from the critters. Now anytime the weather gets hot and dry I pick the fruit early at first blush though I do leave them on the vine in times with cooler weather to ripen longer. I also try to pick them at first blush in rainy times to prevent severe cracking and splitting of course if it rains enough they will split when green.

We have had some fairly hot dry weather the past month but we haven't hit 100 yet this year. It has been raining off and on for the last 24 hours and the long term predictions are for it to continue raining some for the next 10 days. I fear we will see a massive increase in foliage diseases, pests and fruit splitting. I sprayed all the plants with Daconil the day before the rain started but I'm sure that is long gone by now so I will have to resort to using copper if we get a dry day during this spell or the diluted bleach spray if we don't. The stink bugs, worms and leaf footed bugs were just starting the show up the week before the rain so we may have some really intense pest surges over the next week or two. On the bright side it will be a bit cooler but witheringly humid.:roll:

Bill

Hi Bill,

Very interesting post. I admire you especially for how you overcome so many weather and associated gardening adversities in your area (as do so many others with climate challenges on the forum)! It boggles my mind at times :dizzy:

I also had assumed that the tomatoes would ripen in the heat (or "just" get sunscald or get baked/mushy or get blossom drop and the like). I had no idea (or else knew and forgot :?:) that ripening stopped at a certain point. I guess that would explain why my Mt Gem tomatoes have been sitting on the patio looking beautiful but still hard as a rock (or maybe an apple) for the past couple of weeks!! I need an emoticon for "DUH!" :lol:

Anne

This has me wondering and I don't know if anyone has an answer. If temps get above 85 and tomatoes stop ripening because of that, will they resume ripening if the weather cools off or have they shut down permanently and will stay forever green or at blush?

GoDawgs,

They will resume ripening at under 85. I've had a lot of tomatoes on the vine starting to turn when it hit 90-95. A few days later I had beautiful red tomatoes!

D.J., thanks for that. I rather thought that might be the case but we've not had (or seldom had) sustained 100+ conditions and I was curious about that. There have been streaks of high 90's where tomatoes have resumed ripening once the weather broke but thankfully not sustained 100's!

My guess is that they do some ripening overnight?

Tormato - I would hope that you're correct, but I'm not sure.

After a string of days over 100, we're now on about day 2 of a 4-5 day spell of the low 90's and then nothing below 99 degrees for the rest of the 2 week forecast. Most of the highs will be in the 105-110 range.:x It is considerably cooler under the shade cloth, but I'm not sure by how much. I just know it's too hot for me out there!!

Some tomatoes are managing to blush a little but there are lots of green tomatoes just sitting there basically doing nothing, and blossoming has really dropped off. The tomato plants themselves still look great so I'm happy with that. Have lots of peppers producing fruit that are quickly turning red, but tons of leafs are just dropping off. The eggplants are suffering the most :bummer: and I'm hoping I can get them into a better situation.

Cucumbers, on the other hand, are doing great and I'm getting overwhelmed with the production from just 3 plants. I did find an interesting gazpacho recipe today that calls for fewer tomatoes but adds watermelon! Hopefully we won't miss the tomatoes that much and can use up some of the cukes! :yes:

Anne

Another heat related question. I've been wondering about heat vs pollen viability and fruit set. I guess I'm wondering about the point at which pollen becomes useless. Somewhere on T-ville I read a while ago that pollination can occur within unopened buds, so I've been buzzing unopened flower buds to see if fruit set will result early enough in the life of the pollen before hot weather messes it up.

No definitive results yet as I hadn't marked which unopened flower clusters were buzzed. Duh. I will now going forward when the next hot streak comes in. There will be plenty of that in July.

Any thoughts?

well, this site notes reduced fruit set for tomatoes - but mentions pollen sterility for peppers after 35 C

[url]http://www.omafra.gov.on.ca/english/crops/facts/info_tomtemp.htm[/url]

As far as I know, the ripening process is independent from light, which means that they probably do some ripening overnight as long as the night temps go below the "stop" limit. Do they?
And I've read here on the forum that the "stop" limit for pollination is 92°F (33°C). But again, I don't know if we can only go by the day temps. I suppose that pollen formed at temperatures over the limit is damaged and doesn't work. But if the process is ongoing, the pollen formed at lower temps can be okay. I have experience with the low-temp limit said to be 52°F (11°C). As my toms went through a spell of cold weather this year and they were already blooming, I can observe that lots of the flowers weren't pollinated but some on the same truss were. I may be wrong, but that's my experience.
Milan HP