Kenny, not sure if I understand the question - temps around 90 for tomatoes is ok, in a greenhouse, if it gets much above 100 for hours on end, I'd start to worry - but your plants will be drooping on the floor by then.

Word of warning on the electric heat things for the winter - if you can keep the temps above 40, you're good. Try to keep them above 60, and you're going to fall over in shock when you get the electricity bill, eg 4 X normal. I had to buy a separate thermometer switch thing I could set down to 40.

I've forgotten your set up - are you a lean-to or freestanding GH?

Dan

All comments appreciated.
It is a 6 by 10 tent type. single layer. Just green house cloth, built like those pre-formed covers you drop over a car. I had a tarp over part of it this summer for a while. then I sprayed it with that special stuff like white wash. Helped a bit. With out heat, it follows outside temp exactly at night, But boy, does it heat up when the sun hits it. Swamp cooler sets into one end. With dry humidity this week the cooler blows 75 degree air. Keeps it down to about 80 or 85 on a 95 degree day.

Quote: temps around 90 for tomatoes is ok, in a greenhouse, if it gets much above 100 for hours on end, I'd start to worry - but your plants will be drooping on the floor by then. ::::
That gives me a reasonable answer. I think what was bothering me is I have a tray of tomatoes just getting second true leaves. Room temp under the table is 84, but a thermometer beside the seedling will rear 100 to 110. If I place a shade over them it might reduce their growth. If I keep the dirt wet then they should be O.K.
Kenny

Depending upon the variety, tomatoes stop fruit set in mid-hi 90s. They can tolerate the heat, as they are tropical. You may want to think about how you can get some vents in the top to get rid of some of that heat.

Dan

The rose isn't the same as the tomato. For one thing, one isn't trying to "ripen" a rose.

In the rose greenhouse, such high temperatures could not be tolerated. 85 was as high as the greenhouses were allowed to go. Overnight, winter and summer, temperatures may drop as low as 60 before the furnaces would come on.

(I think I'm all dun trying to use the degree symbol. GW doesn't know what it is usually. I could say something about GW being as archaic as the Imperial system of measurement but I suppose I'd be off by centuries. ;o)

Before the marketing industry turned to Columbia for the majority of our roses, Colorado was thought to be an important center for rose production. Your abundant winter sunshine, makes the state a very good choice for winter growing.

Ventilation is important. When outdoor temperatures are low but the sun is bright, roof venting is the way to go. Often, it takes very little for the warm air to escape.

Steve

Kenny, what are your plans for the new tomato starts? If I don't misremember, you had something set up indoors in the house?

I came up with a cross bred tomato ( a seed sent to me)that is really nice and I am trying to grow it out. At least to see what the F2 looks like. I am trying to push them before cold weather. I will put 2 or 3 in 5 gal buckets to bring in as a last resort. At 81, "next year" is not an option.
My last year with in the window in tubs taught me a lot, but did not go very well. Biggest item was the red LED brought the drug People to check.