What temperature is too cold?

Mark0820 · May 3, 2011

With all of the rain we had in April, my tomato plants have been on the porch for the last two or so weeks (I usually plant around Apr. 24). The rain has continued into May and we are experiencing some cooler weather for this time of year (it is currently 45 degrees, but should be closer to 60 - 65). The night time temperature for tonight and tomorrow night could be in the 36 - 38 degree range. Since my plants have been outside for at least two weeks, will they handle 36 - 38 degree weather or should I bring them in the house at night?

barkeater · May 3, 2011

If it isn't too much trouble I'd bring them in those 2 nights. Otherwise make sure they are in a protected spot from the frost like against the house, under a tree, etc.

Mark0820 · May 4, 2011

Thanks for the input barkeater. I brought the plants in the house last night and the temperature ended up being 40 degrees. Tonight there is a frost warning, so I brought them in again.

After tonight, the temperatures are headed back to the upper 60's and low 70's (with a break in the rain), so I might have a chance to plant the tomato plants tomorrow or Friday.

kath · May 4, 2011

Last year a min/max thermometer that we have outdoors registered 36.2 for a low temp, but over 1/2 my tomato plants were killed and many more suffered damage from the cold. This despite the fact that coverings of all types were used on most of them.

Glad to hear they're safe inside.

Stepheninky · May 4, 2011

Kath the reason for that is the same reason it can frost when temps are above freezing. The weather reports thermometer is on a tower so its above 5 ft at least the thermometer that most people place outside are at least 3 feet above the ground. The temp at ground level is actually colder. The reason is that you have high elevation cold air mixing with the warmer air. Cold air is heavier so a thin sheet of the much colder air drops and forms at the ground level. So even if where your getting your reading says 38 or 40 Deg F at ground level it could be closer to 32 deg F. Also wind can have an added effect (think wind chill) on helping to make it frost.

So your 36.2 at ground level could have actually been in the mid to high 20's range.

Hope that explanation makes since

beatpoet · May 4, 2011

I have been bringing mine inside as well the last couple of nights as well. Usually if its going to get down to 40 or below I've been doing that. I was able to plant things in April last year, but this year, not so much. Hopefully this'll be the last week of this cold, I'm ready for spring.

kath · May 4, 2011

Quote:

Originally Posted by Stepheninky

Kath the reason for that is the same reason it can frost when temps are above freezing. The weather reports thermometer is on a tower so its above 5 ft at least the thermometer that most people place outside are at least 3 feet above the ground. The temp at ground level is actually colder. The reason is that you have high elevation cold air mixing with the warmer air. Cold air is heavier so a thin sheet of the much colder air drops and forms at the ground level. So even if where your getting your reading says 38 or 40 Deg F at ground level it could be closer to 32 deg F. Also wind can have an added effect (think wind chill) on helping to make it frost.

So your 36.2 at ground level could have actually been in the mid to high 20's range.

Hope that explanation makes since

Thanks, it does make sense.

I've seen that 10-day forecasts can change and can be wrong by too many degrees on a single night for me to consider risking so many plants ever again, though. Even though I started 6 plants early this year for an early risk, I still haven't been brave enough to put them out!

For me, it's easier to wait a couple weeks longer to sow and plant out than to worry about the weather and come up with plan B if the worst happens.

HoosierDaddy · May 9, 2011

Kath,

I've had 7 of my tomato plants and 4 of my hot pepper plants in the ground since April 28th. This is very early for SE Michigan. Each plant is protected with "Kozy Coats". These " water walls" go by other names like "Wall O Water", "Water Walls".
We had two nights down to 29 degrees F and the plants are fine.

I will remove the Kozy Coats around May 15th from the tomato plants and May 30th for the peppers.
I too have some spare plants just in case something went really wrong with the cold spell but so far in two years, all my backup plants get donated to a neighbor.

King Carrot · May 9, 2011

Quote:

Originally Posted by HoosierDaddy

Kath,

I've had 7 of my tomato plants and 4 of my hot pepper plants in the ground since April 28th. This is very early for SE Michigan. Each plant is protected with "Kozy Coats". These " water walls" go by other names like "Wall O Water", "Water Walls".
We had two nights down to 29 degrees F and the plants are fine.

I will remove the Kozy Coats around May 15th from the tomato plants and May 30th for the peppers.
I too have some spare plants just in case something went really wrong with the cold spell but so far in two years, all my backup plants get donated to a neighbor.

Any chance of some photos of the Toms with their coats on?

Thinking of doing something like this next year myself

!

HoosierDaddy · May 9, 2011

If I can find my camera I will take those photos. Haven't a clue where that little camera got misplaced this time. Off to search.

kath · May 9, 2011

Quote:

Originally Posted by HoosierDaddy

Kath,

I've had 7 of my tomato plants and 4 of my hot pepper plants in the ground since April 28th. This is very early for SE Michigan. Each plant is protected with "Kozy Coats". These " water walls" go by other names like "Wall O Water", "Water Walls".
We had two nights down to 29 degrees F and the plants are fine.

I will remove the Kozy Coats around May 15th from the tomato plants and May 30th for the peppers.
I too have some spare plants just in case something went really wrong with the cold spell but so far in two years, all my backup plants get donated to a neighbor.

It's great that you've had such great luck with the Kozy Coats and the weather. I don't have a way to protect all the plants that I grow or enough lights to grow duplicates of all of them to the replacement size. Having lost so many last year, I played it really safe this year. I still will have some extras of the red and pink beefsteaks, as well as some paste and cherry types left over for donating if all goes well. Maybe I'll start to push the envelope again someday when I can keep the total number of plants I grow to a more reasonable size.

May 3, 2011	#1
Mark0820 Tomatovillian™ Join Date: Oct 2010 Location: Cincinnati Posts: 907	What temperature is too cold? With all of the rain we had in April, my tomato plants have been on the porch for the last two or so weeks (I usually plant around Apr. 24). The rain has continued into May and we are experiencing some cooler weather for this time of year (it is currently 45 degrees, but should be closer to 60 - 65). The night time temperature for tonight and tomorrow night could be in the 36 - 38 degree range. Since my plants have been outside for at least two weeks, will they handle 36 - 38 degree weather or should I bring them in the house at night?

May 3, 2011	#2
barkeater Tomatovillian™ Join Date: Jan 2006 Location: NE Kingdom, VT - Zone 3b Posts: 1,439	If it isn't too much trouble I'd bring them in those 2 nights. Otherwise make sure they are in a protected spot from the frost like against the house, under a tree, etc. __________________ barkeater

May 4, 2011	#5
Stepheninky Tomatovillian™ Join Date: Aug 2010 Location: Kentucky Posts: 682	Kath the reason for that is the same reason it can frost when temps are above freezing. The weather reports thermometer is on a tower so its above 5 ft at least the thermometer that most people place outside are at least 3 feet above the ground. The temp at ground level is actually colder. The reason is that you have high elevation cold air mixing with the warmer air. Cold air is heavier so a thin sheet of the much colder air drops and forms at the ground level. So even if where your getting your reading says 38 or 40 Deg F at ground level it could be closer to 32 deg F. Also wind can have an added effect (think wind chill) on helping to make it frost. So your 36.2 at ground level could have actually been in the mid to high 20's range. Hope that explanation makes since __________________ tomatoprojects.blogspot.com

May 4, 2011	#4
kath Tomatovillian™ Join Date: Jan 2010 Location: zone 6b, PA Posts: 5,664	Last year a min/max thermometer that we have outdoors registered 36.2 for a low temp, but over 1/2 my tomato plants were killed and many more suffered damage from the cold. This despite the fact that coverings of all types were used on most of them. Glad to hear they're safe inside.

May 4, 2011	#6
beatpoet Tomatovillian™ Join Date: Mar 2011 Location: Cincinnati, Ohio Posts: 214	I have been bringing mine inside as well the last couple of nights as well. Usually if its going to get down to 40 or below I've been doing that. I was able to plant things in April last year, but this year, not so much. Hopefully this'll be the last week of this cold, I'm ready for spring.

May 9, 2011	#8
HoosierDaddy Tomatovillian™ Join Date: Jul 2010 Location: Zone 5 SE Michigan Posts: 50	Kath, I've had 7 of my tomato plants and 4 of my hot pepper plants in the ground since April 28th. This is very early for SE Michigan. Each plant is protected with "Kozy Coats". These " water walls" go by other names like "Wall O Water", "Water Walls". We had two nights down to 29 degrees F and the plants are fine. I will remove the Kozy Coats around May 15th from the tomato plants and May 30th for the peppers. I too have some spare plants just in case something went really wrong with the cold spell but so far in two years, all my backup plants get donated to a neighbor.