Hardening Off

recruiterg · May 2, 2009

My seedlings are about 4-6 inches tall and growing in 18 oz Solo Cups. I have been putting them outside around 10:00am and bringing them in around 4:30pm with no problems except on windy days they seem to get a little beaten up.

Question:

- At what point can I feel confident that I can leave them outside overnight? How do you know? Is there anything to look for or to key on?
- What minimum temperatures should I pick them up and move them back in the garage? I don't have a cold frame.

I would appreciate general thoughts/strategies on hardeng off. Thanks in advance...

newatthiskat · May 2, 2009

This is what I did this year. Does not mean it is right or even good

If temps were going to below 40 I brought them into garage. I just threw them outside. I started out with them in a shady area. Then I moved them to a partially shady area then full on sun. I did have some small amount of windburn and sunburn but they all lived through it. Worth told me when I asked him about temps. "Mine go out in the cold and die in the cold" and you know what? He is right

Kat

ddsack · May 2, 2009

Recruit - I am about 200 miles north of you, and our spring temps keep us about 2 weeks behind you. I try to not baby my plants too much, because I've got a smaller time window to get them in the ground so they ripen before our earlier fall. I want them ready to go in as soon as ground and air conditions permit.

I try to get them out from under fluorescent lights as soon as I can, preferably right after sprouting if weather allows. I do have an old leaky,tattered plastic greenhouse that I can house them in during the day while they are young and need the heat for good growth. They have to come in at night, or when cloudy days keep the temps in the greenhouse in the 50's. Now that they are of a good size, I want to keep them in more of a holding pattern until planting, so they gradually get moved outside into the cooler temps. Once they are used to being outside the whole day, I only bring them in when I think there may be a chance of frost. Usually, anything below 40 degrees over night, because I don't have much confidence in weather forecasts. Especially if you get a clear night with no wind, temps here can drop lower than predictions. I have about 12 flats of various seedlings that I have to carry uphill into the garage, so it's a really pain in the butt to do , but not worth the risk of losing all my work, and I keep telling myself I really need the exercise.

Barbee · May 2, 2009

Once mine can stay outside in the full sun all day without wilting, I figure they can stay outside during the night. If we have a cold snap (under 40's) then I haul them into the garage for the night.
To be honest, once I start leaving them out all night, I'm more worried about critters eating them than the cold.

Cherokee_Motley · May 2, 2009

Wow Zone 4...

And I think I have a short growing season. I have always tried to live by the 50 degree rule. If it is going to be below 50, I pull them back in the house for a night.

However, if you seedlings are 4-6" tall now is a good time to do a transplant and get the roots goings.

Lastly, once I do put them out I do like Newatthiskat. Move them around my deck from shade to P-shade to P-sun, etc.

Best of Luck...

barkeater · May 2, 2009

I get mine out as soon as possible. Even though it could be 4 more weeks before planting out, sunlight has to better than fluorescents. I use window screens to shade them. When they first go out they go behind 2 window screens between 10am and 4pm. And early on, they come back in after dark whatever the forecast, although it probably wouldn't hurt leaving them out if it isn't windy or rainy.

They have been out enough now the past 2 weeks that I'm about ready to reduce it to one screen.

May 2, 2009	#1
recruiterg Tomatovillian™ Join Date: Jan 2009 Location: Edina, MN (Zone 4) Posts: 945	Hardening Off My seedlings are about 4-6 inches tall and growing in 18 oz Solo Cups. I have been putting them outside around 10:00am and bringing them in around 4:30pm with no problems except on windy days they seem to get a little beaten up. Question: - At what point can I feel confident that I can leave them outside overnight? How do you know? Is there anything to look for or to key on? - What minimum temperatures should I pick them up and move them back in the garage? I don't have a cold frame. I would appreciate general thoughts/strategies on hardeng off. Thanks in advance...

May 2, 2009	#2
newatthiskat Tomatovillian™ Join Date: Mar 2008 Location: texas Posts: 1,451	Reply This is what I did this year. Does not mean it is right or even good If temps were going to below 40 I brought them into garage. I just threw them outside. I started out with them in a shady area. Then I moved them to a partially shady area then full on sun. I did have some small amount of windburn and sunburn but they all lived through it. Worth told me when I asked him about temps. "Mine go out in the cold and die in the cold" and you know what? He is right Kat

May 2, 2009	#4
Barbee Tomatovillian™ Join Date: Mar 2008 Location: SW Ohio Posts: 1,818	Once mine can stay outside in the full sun all day without wilting, I figure they can stay outside during the night. If we have a cold snap (under 40's) then I haul them into the garage for the night. To be honest, once I start leaving them out all night, I'm more worried about critters eating them than the cold. __________________ *Barbee*

May 2, 2009	#5
Cherokee_Motley Tomatovillian™ Join Date: May 2006 Location: Raleigh, NC Posts: 18	Wow Zone 4... And I think I have a short growing season. I have always tried to live by the 50 degree rule. If it is going to be below 50, I pull them back in the house for a night. However, if you seedlings are 4-6" tall now is a good time to do a transplant and get the roots goings. Lastly, once I do put them out I do like Newatthiskat. Move them around my deck from shade to P-shade to P-sun, etc. Best of Luck... __________________ To grow a heirloom tomato is to grow a little taste of history.

May 2, 2009	#3
ddsack Tomatovillian™ Join Date: Jan 2006 Location: Northern Minnesota - zone 3 Posts: 3,220	Recruit - I am about 200 miles north of you, and our spring temps keep us about 2 weeks behind you. I try to not baby my plants too much, because I've got a smaller time window to get them in the ground so they ripen before our earlier fall. I want them ready to go in as soon as ground and air conditions permit. I try to get them out from under fluorescent lights as soon as I can, preferably right after sprouting if weather allows. I do have an old leaky,tattered plastic greenhouse that I can house them in during the day while they are young and need the heat for good growth. They have to come in at night, or when cloudy days keep the temps in the greenhouse in the 50's. Now that they are of a good size, I want to keep them in more of a holding pattern until planting, so they gradually get moved outside into the cooler temps. Once they are used to being outside the whole day, I only bring them in when I think there may be a chance of frost. Usually, anything below 40 degrees over night, because I don't have much confidence in weather forecasts. Especially if you get a clear night with no wind, temps here can drop lower than predictions. I have about 12 flats of various seedlings that I have to carry uphill into the garage, so it's a really pain in the butt to do , but not worth the risk of losing all my work, and I keep telling myself I really need the exercise.

May 2, 2009	#6
barkeater Tomatovillian™ Join Date: Jan 2006 Location: NE Kingdom, VT - Zone 3b Posts: 1,439	I get mine out as soon as possible. Even though it could be 4 more weeks before planting out, sunlight has to better than fluorescents. I use window screens to shade them. When they first go out they go behind 2 window screens between 10am and 4pm. And early on, they come back in after dark whatever the forecast, although it probably wouldn't hurt leaving them out if it isn't windy or rainy. They have been out enough now the past 2 weeks that I'm about ready to reduce it to one screen.