Temps in the 40's are not going to harm your tomatoes. They won't get much growth until temperatures are higher, but I would quit covering them and let them dry out.

The only time I would cover tomatoes is if a freeze is forecast. Hope that helps and good luck.

Agree. 40s won't hurt them but keeping them covered can. Cover only if the air temps at ground level are in the lower 30s. Set a thermometer at plant level since forecast air temps are at the 5-6' level.

Dave

Will do as you 2 suggest. Thanks a bunch!

I disagree with what has been posted based on scientific findings concerning temperatures and damage.

No they wont "freeze" but plants have shown to get damaged at temperatures below 45. Much depends on the variety, how hardened they are when the exposure started, the amount of wind and the length of exposure but it would be best to keep them covered for now.

At temps below 55F most plants just sit there.

I dont have access to scientific data but have planted tomatoes in the past when night lows had dropped to low 40s and hi 30s. And my plants did fine that season.
More than air teperatures, soil temperatures are important.
When soil temperature measure over 60, during the day, it is not going to cool down considerably (at roots level at night) even when air temperature goes down to 30s.This is especially true, if the plant is mulched well.
But as mentioned above, surviving is one thing and growing another. That is why , in my experience, late planted tomatoes catch up with the early one, very fast in warmer soil and air temperature.

I am a total newb, but I have to agree with mulio. I started a few seeds in a cold frame in the middle of December (average low 40). The seedlings started great but showed obvious cold stress later. I then started the same seed indoors with artificial light and brought the outdoor seedlings indoors to place under this same light. The cold stressed plants never recovered and my new seedlings outgrew the competition.
I would suggest not placing them outdoors until the temps are averaging 55, or 50 but with some form of cover. Good luck.

We just had a 7 day stretch of weather like metioned in the opening post. My plants got hammered and took some damage and didn't look great. Since then the weather here has warmed up (80 expected the next 2 days) and my plants are bouncing back very nicely.

Damon

I think the problem is a lot of people set out tomatoes that are not properly hardened off. A tomato plant that is ready for the outdoors should have no problems at 40 degree temps. In my opinion high winds are much more of a problem than cool temps.

I have no scientific evidence to back up my statements, all I have is 50 years of gardening experience.

Eetrey, 40 is too cold for small seedlings. Gotta make them tough first.