The 90 degree myth

[Wi-sunflower]

I would say it's the nite temp as well.

I have about 30 plants in 3 gal pots in the greenhouse. The Pink Tumblers set fruit super well even tho day temps were well above 90* any time the sun was out. The Black Cherries haven't done nearly as well tho.

These days the day temps inside the end opened and 1 side opened GH is well over 100 with high humidity especially after watering. BUT our nites do generally drop below 70*.

This week we will be higher tho as part of the heat bubble. I expect there will be a drop off of new fruit for a while.

Carol

[Dak]

Carol, I think you're right, it's the nighttime temps along with humidity. I'm in California, for the last month our temps have averaged 97, but our nighttime temperature can drop down into the low 50's. I'm getting new fruit forming on just about all my tomatoes, black cherry, Jaune Flamme, Arbuznyi (going crazy with new tomatoes), pink BTD (though BTD isn't producing much) Kosovo, black and brown boar, bulgarian triumph. What is slow is known to be slow, Brad's Black Heart. I don't want to jinx anything, but this could be my best tomato year ever.

[ronsmith100]

Carol you explained a lot to me.. so have all of you.
Should you care to follow along with temps you can find highs and lows "accuratly" at accuweather.com for Kanab UT.

Here is what I am seeing this year.

Celebrity doesn't seem to care what the temp is... doesn't even have a UV screen. It's an early and I panted it late just to see. Setting spider leafs today! But is is determinate and will not last long.

Dinner Plate total failure.. thin and wispy leaves and not a blossom all year.

Chucks Yellow... nothing

Super Sioux doing great even in the heat

Mexico probably not enough sun where I planted it.

Early girl cannot be killed ever! Lots of medium fruit

Chocolate Stripes... waiting

I'll let you know how it works in September... I suspect some will do well even into October.

[b54red]

I always get some plants setting fairly good even in the hottest weather and with constant high humidity. They don't set nearly as many nor do the plants or fruit get as large. I find my poorest fruit set occurs when the weather gets extremely dry and hot and it is hard to keep the plants watered sufficiently. Of course right now I am having the opposite problem with too much rain and no way to keep the plants sprayed so the diseases are running rampant. I have decent fruit set if I can keep the plants alive and if the fruit doesn't split. I threw away over 50 nice busted tomatoes today and only salvaged about a dozen. I also had to pull up about a dozen plants that were just destroyed by foliage diseases or fusarium.

[rwsacto]

Our temps here in central CA have been unusually cool lately: 80's in the day and 50's at nite. (Not complaining mind you) .

Today on the radio garden show, a horticultural professor said that the reason our tomatoes are not growing well here is that the plants quit growing when the temperatures fall below about 55 degrees. She suggested that covering them with row cover or bedsheets at nite would retain some warmth and help them along.

Of course when it gets hot again, we are supposed to use shadescreens to prevent sunscald.

I have to cover plants in the winter and now all summer too? sheesh

Rick

[ronsmith100]

What happens to the tomatoes that cant take the summer heat? Do they recover in the fall?

I have observed heat tolerances in some varieties over the years in my garden. For the past few weeks, we have been over 100 degrees in the day time and 85 degrees at night. An early hybrid I grew this year named Fourth Of July was the earliest producer at less than sixty days. After the plant matured and reached it's full height, the stems became woody and the plants lost most of their leaves. I cut the plants back to the point where they were producing new growth from the woody stems. They have now reached their maximum height again and produced new blooms and set new fruit. The plants are loaded with fruit again. It looks like the second growth will produce as abundantly as the early growth did.

A few of my open pollinated varieties are exhibiting the same heat tolerant tendencies as the hybrids. All of my plants were pruned back to the new growth level after producing a good spring/early summer crop of tomatoes.

The secondary growth on my plants may even exceed the growth and production rates of my spring tomatoes. because they are growing from a fully developed root system supplying all the moisture and nutrients the new growth needs. My spring tomatoes can only grow as fast as the developing root structure allows.

Ted

Originally Posted by ronsmith100

What happens to the tomatoes that cant take the summer heat? Do they recover in the fall?

The few varieties I grow that can't take the heat simply die. I replace them with new plants grown from cuttings. Of the thirty two varieties I grew this year, maybe five or six varieties died from the heat. A few varieties are slow to recover from the heat, but will recover and produce again. Other varieties act like the heat was only a bump in the road and keep on growing and blooming.

Ted

[Dewayne mater]

Well a squirrel ate 1/2 of a nice Cowlick brandywine that was almost ready GRRR! Furry rats.

I added liquid fertilizer to my tainers a couple of times about 3 and 1 week ago. That resulted in a growth spurt and a lots of blooms. Most didn't set. However, I was surprised this morning to see that Earl's Faux had not 1 but 4 small tomatoes growing. Under the conditions like Ted mentioned, this is remarkable to me.

[kath]

Originally Posted by ronsmith100

What happens to the tomatoes that cant take the summer heat? Do they recover in the fall?

We had a horrifically hot summer here last year and although production shut down on some and slowed on others, we were never without tomatoes all season. As soon as things cooled down at night a bit, more fruit would set and by fall, the growth at the tops of the plants was lush and they were loaded with greenies again. Quite a few ripened indoors when I had to pick before frost in Oct.

Like Kath, most of my plants produce new growth at the tall tips of the plants. For many years, I let my plants continue to grow and hang over the cages and trellis. They would eventually produce blooms and fruit on the growing tips. I found a few years ago, if I cut the plants back severely after new growth has started emerging near the bottom of the plants, the new growth produces much better, and larger fruit in the fall than the growing tips of the old growth.

Seasonal conditions between the southern states and northern states may cause tomato plants to not produce the same results. In the hot southern climate, severe pruning works well for me because we have two distinct growing seasons before and after the summer heat. In the shorter season northern states; late season production from the growing tips may work better.

Ted

[luke]

Look into photosynthesis. You hit 94-95 degrees, and the only photosynthesis happening is in kudzu and johnson grass.

Trust me on this one.

[chalstonsc]

Ted,
When you say"if I cut the plants back severely after new growth has started emerging near the bottom of the plants....", how do you get the new growth to start near the bottom? I ask because when the heat/humidity really hits around here, which has been for the past couple of weeks this year, I don't have any new growth left near the bottom....only at the tips and that usually isn't great. Can you describe your method/timing of cutting back?
I cut back the past two years....year before last worked well, but last year did not work at all, I think because I cut back too severely, and had no new growth at the bottom? Thanks

Tom

[Keiththibodeaux]

I am curious about this as well. By the full heat of summer, the plants look so bad that most just rip them out and plant new ones in July for the fall harvest. I have always wondered if you could cut back hardy plants back severely and if they would come back, but since no one does that I know of, I just put in fall plants too. Maybe next year I will give that a try along with the shade cloth thing.

[Stepheninky]

Originally Posted by Keiththibodeaux

I am curious about this as well. By the full heat of summer, the plants look so bad that most just rip them out and plant new ones in July for the fall harvest. I have always wondered if you could cut back hardy plants back severely and if they would come back, but since no one does that I know of, I just put in fall plants too. Maybe next year I will give that a try along with the shade cloth thing.

What I do is when the heat gets super bad late July to august for me is as the plants die from the bottom up I just keep the yellowing bottom stems pruned. Yellowing stems do not contribute anything to the plant and use resources. I have had four or five feet of bottom vine that was bare (from pruning) with 3 ft or so of the top of the vine still very healthy when the weather starts to cool. Sept and October I will still be able to harvest fruit and before the last frost I will pick any remaining green tomatoes to make Amish Green tomato relish (recipe is on the forums some where).

Not sure how everyone else does it but that is my method. I use cages and tie off the trimmed bottom vine to help support the plant.