down to 40 F

[bower]

Originally Posted by MickyT

I'm playing around with a few plants this year just to see what happens and to compare early and later plantings. I put out 6 week old transplants on March 15 into my unheated high tunnels. Some in 12 gallon grow bags and some into raised beds covered by the tunnel. The day temps have been 45 - 55 and night temps 36 - 42 since then. The tomatoes in raised beds showed severe cold stress and I ended up pulling them all. However, the plants in grow bags are faring better. You can definitely tell they were stressed with yellow leaves, it looks like they really struggled to uptake nutrients. But recently they are showing positive signs - the new growth is nice and green and one of them is starting to show tiny flowers forming at the growing tip (Stupice). The other varieties that look to be surviving and putting out nice new growth are Oregon Spring and Jaune Flamme.

In ground would be colder soil than the grow bags, even in a raised bed. Good point.
Are those temperatures outdoors or in the high tunnel itself?

[MickyT]

Originally Posted by bower

In ground would be colder soil than the grow bags, even in a raised bed. Good point.
Are those temperatures outdoors or in the high tunnel itself?

Those are outdoor temps. At night the high tunnel is the same as the outside low (maybe a little lower as discussed in other threads here, haven't tested myself). But during the day if it's sunny and 55 outside it can be 70-80 in the tunnel. We haven't had many sunny days but I think even on an overcast day it's probably 10 degrees warmer inside the tunnel than outside. So I think the "cold at night followed by really warm during the day" is happening there to a certain extent.

[Worth1]

No.

Worth

[OzoneNY]

I covered mine last night. I woke this AM to see 31F on the thermometer. They are still covered I will leave them covered till the temp goes back above 40. Forecast say that will not happen until Sunday morning. For a little warmth, I stuff two C5 Christmas lights under the each of the covers from an old string I had in my attic.

[AlittleSalt]

Ozone, I didn't cover mine...It's almost 3pm and 36F in Fort Worth and 34F at my house. My tomato plants look awful. It was 50F degrees warmer yesterday.

[Nan_PA_6b]

Bower, how did your plants do?

Nan

[bower]

Nan, my plants are cozy in the house so far! Been watching the greenhouse temperatures and keeping track of the weather outside and what I can expect. Hoping to plant any time after the 15th of April, but the long range isn't looking good.
I'm definitely to the point where 40F seems to be the lowest night time low.
Problem is, on a day like today with no sun, the high temp was 44 F.
I guess it's all about the sunshine now... but will see if it drops lower than 40 after a day of 44.

[edweather]

40 is borderline. My big concern was frost. If I was confident of no frost, no worries. Not much growth in cool weather, but other than that, no damage. If there are any doubts, some sort of protection is definitely in order.

[Gardeneer]

Agree with Ed.
Tomatoes can tolerate cold air down to freezing mark, in the case of night lows. If day temps are also cold then they will just sit pretty with no growth

I have grown tomatoes in cool weather PNW for 4 season where night lows wil stay under 50f til mid July. But i managed to have some early varieties with ripe tomatoes by then , like Bloody Butcher Siletz. Those varieties planted the same date down here would produce ripe tomatoes 4 weeks sooner.
The pointI amaking is that cold tolerance is one thing and growth another.

[OzoneNY]

All Survived. My outdoor thermometers read 33 and 32 deg over night temp on Saturday.
You can see the day before I cover with rubbish bags and for a little heat I ran a set of old Christmas lights (2) for each plant.
When I remove the black plastic bags on Sunday afternoon it seem everyone the kids are doing just fine

IMG_1349.jpg

IMG_1353.jpg

[Darren Abbey]

Originally Posted by bower

Just looking for a reality check, from everyone, everywhere.
Have you seen any harm from a night time low of 40 F, on
(a) seedlings in pots
(b) plants in the ground or (full size) containers

assuming there is some protection, either a greenhouse or other temporary shelter.

I know a 40 F night is not ideal. I just want to know your experience, how well your plants survived it. TIA!

I've had tomato seedlings survive snow falling on them. Only a few hours, then into some warmth, but still.

[greenthumbomaha]

A few years ago there was a later May frost and nipped the entire 70 tomatoes. They were pretty mature at that time as I start seedlings early and trench plant. We replaced most but kept a row because there was nothing to loose. Everyone else got frosted and it was late in the season= shelves were empty! The damaged plants grew back from the bottom and caught up quickly.

On the flip side , I left some young seedlings outside this month when it was supposed to be nice. As they say wait 15 minutes. While I was away the weather turned cloudy windy and cold, and that tray is noticeably flaccid and not doing well.. I had sprinkled them so they wouldn't dry out. Cold plus wet not good as noted many times House temp with no sun to warm inside was not enough to reverse the cold damage. Not ready to toss but time will tell.

- Lisa

[BigVanVader]

No point in planting tomatoes if the soil isn't 65 degrees or so, IMO. A soil thermometer is a worthy investment. Plus in every study I have seen the later plantings of tomatoes always outperform the early. I understand the itch, but it just isn't worth the bother.

[Nan_PA_6b]

Ozone, that fence is cute!

Nan

[edweather]

@Ozone, great job with the protection.

Just for a 'can you top this,' when I was in cold z5 even borderline z4, I did everything possible to get tomatoes planted early with maximium protection in our short season. Always used wall-o-waters. They claim to protect down to 16F. I had snow on WOWs once, and the WOWs froze solid once.....plants did fine. I have pics somewhere, but that was 20 years ago.