Moving plnts in and out..safe temps in the a.m.?

mensplace · March 8, 2018

Our weather has been and still is crazy. For weeks in the 80's and moderate at night. Seedlings are beautiful! Now, and through mid April it will be moderate in the daytime bit with lows often in the twenties. At night they come inside next to the heater, then I take them out when it warms up for a day in full sun. Little wind. SO, how cold is too cold for the morning trip outside? The seedlings all have been out all day in the wind and sun, and they have their trues leave now , but thin stems. Right now it is 36.

clkeiper · March 8, 2018

well, as long as its above freezing they won't freeze but the cold temps will damage the newly forming unseen to us blossoms deep withing the cells. if you don't accidentally kill them expect cat faced tomatoes for the first flush maybe even two of fruits. cold temps often result in fungal pressure for me.

jtjmartin · March 8, 2018

I generally don't try to harden my tomatoes when the temp is in the 30s - 36 degrees at 5 feet can be freezing temps on the ground or in low pockets.

Today it is in the 40s currently. No wind, so three feet inside the garage its 55 and the angle of the sun is low enough that the seedlings get some sun-hardening. Definitely makes them greener and thicker!

Nan_PA_6b · March 8, 2018

I don't know that there's much point in putting them outside in the 30's or 40's. They are not going to do much growing at those temps. If they're next to a heater at night, then the cold outdoor temps are going to be a real shocker. I guess I'd let it get up into the 50's or so before putting them out.

Nan

SueCT · March 8, 2018

It seems to me the plants need hardening off to sun and heat, not cold, so I am not sure how much benefit they will get anyway for the amount of work involved in bringing them in and out all those times. I have brought them out when it was in the mid to high 40s in the am only if I knew it was going to warm up quickly that day. If it was going to stay 40s-low 50s, I personally just skip it and wait for better weather. We have such extreme of temps in the spring it is difficult getting them hardened off adequately but I wouldn't assume that gave them much protection against sudden higher temps. I usually only harden off half my plants or less at a time, so if somethinig goes wrong there are still back ups. But if you have the time and want to get started, what the heck. It would be interesting if you kept some plants back and waited for warmer weather to harden those off and then see what happens with each group when they go into the garden.

Father'sDaughter · March 8, 2018

Somewhere, there is a post by DarJones describing what happens at each temperature range. I'm not able to find it, but did keep some notes.

Over 92F pollen start clumping and blossoms drop in nature plants

72-92F is the Goldilocks zone for growth, flowering and fruit set

65-72F is the ideal range for growing seedlings

50-65F is the beginning of cold stress with growth ceasing below 60F

32-50F severe cold stress and probable damage

26-32F if frost occurs, death; otherwise stunted growth, damage and long recovery time when temps rise

Below 26F pretty much kiss them goodbye

I don't start hardening off until 7 to 10 days before plant out.

March 8, 2018	#1
mensplace Tomatovillian™ Join Date: Dec 2009 Location: USA Posts: 1,013	Moving plnts in and out..safe temps in the a.m.? Our weather has been and still is crazy. For weeks in the 80's and moderate at night. Seedlings are beautiful! Now, and through mid April it will be moderate in the daytime bit with lows often in the twenties. At night they come inside next to the heater, then I take them out when it warms up for a day in full sun. Little wind. SO, how cold is too cold for the morning trip outside? The seedlings all have been out all day in the wind and sun, and they have their trues leave now , but thin stems. Right now it is 36.

March 8, 2018	#2
clkeiper Tomatovillian™ Join Date: Nov 2011 Location: ohio Posts: 4,350	well, as long as its above freezing they won't freeze but the cold temps will damage the newly forming unseen to us blossoms deep withing the cells. if you don't accidentally kill them expect cat faced tomatoes for the first flush maybe even two of fruits. cold temps often result in fungal pressure for me. __________________ carolyn k

March 8, 2018	#3
jtjmartin Tomatovillian™ Join Date: May 2016 Location: Williamsburg VA Zone 7b Posts: 1,110	I generally don't try to harden my tomatoes when the temp is in the 30s - 36 degrees at 5 feet can be freezing temps on the ground or in low pockets. Today it is in the 40s currently. No wind, so three feet inside the garage its 55 and the angle of the sun is low enough that the seedlings get some sun-hardening. Definitely makes them greener and thicker!

March 8, 2018	#4
Nan_PA_6b Tomatovillian™ Join Date: Dec 2016 Location: Pittsburgh, PA Posts: 3,194	I don't know that there's much point in putting them outside in the 30's or 40's. They are not going to do much growing at those temps. If they're next to a heater at night, then the cold outdoor temps are going to be a real shocker. I guess I'd let it get up into the 50's or so before putting them out. Nan

March 8, 2018	#5
SueCT Tomatovillian™ Join Date: Jan 2012 Location: Connecticut Posts: 1,460	It seems to me the plants need hardening off to sun and heat, not cold, so I am not sure how much benefit they will get anyway for the amount of work involved in bringing them in and out all those times. I have brought them out when it was in the mid to high 40s in the am only if I knew it was going to warm up quickly that day. If it was going to stay 40s-low 50s, I personally just skip it and wait for better weather. We have such extreme of temps in the spring it is difficult getting them hardened off adequately but I wouldn't assume that gave them much protection against sudden higher temps. I usually only harden off half my plants or less at a time, so if somethinig goes wrong there are still back ups. But if you have the time and want to get started, what the heck. It would be interesting if you kept some plants back and waited for warmer weather to harden those off and then see what happens with each group when they go into the garden.

March 8, 2018	#6
Father'sDaughter Tomatovillian™ Join Date: Nov 2011 Location: MA/NH Border Posts: 4,919	Somewhere, there is a post by DarJones describing what happens at each temperature range. I'm not able to find it, but did keep some notes. Over 92F pollen start clumping and blossoms drop in nature plants 72-92F is the Goldilocks zone for growth, flowering and fruit set 65-72F is the ideal range for growing seedlings 50-65F is the beginning of cold stress with growth ceasing below 60F 32-50F severe cold stress and probable damage 26-32F if frost occurs, death; otherwise stunted growth, damage and long recovery time when temps rise Below 26F pretty much kiss them goodbye I don't start hardening off until 7 to 10 days before plant out.