hardening off and maybe killed them

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mr_yan

New Member
I start my seeds in a large cooler with a 14 W CFL bulb as a heat source and initial light source. Today I took the box with five day old tomatoes and peppers outside for about 90 minutes starting at about 4:45 while we were on our evening dog walk. With the light bulb the temp in the box is easily 90 F. Outdoor temp was about 60F. The white styrofoam box was in the sun but the side walls shaded the plants.

When I checked on the plants after we got back about six of the twenty cups of plants had wilted. The box is back inside with the lamp in it now. Mostly it looks like my grape tomatoes were effected but at least one cherokee purple also got it.

Was I getting too greedy by moving them into natural light so soon? Think it was mainly the temps that did them in? Just start new ones or keep trying with these?
 

Kya D

Active Member
I only harden my seedlings off for about 10 minutes at a time for the 1st few days and then I add a few minutes each week.
But I don't have very good luck with seedlings.
 

RonsGarden

Super Moderator
Staff member
Going from 90F down to 60F would shock your seedlings!
I'd wait until the daytime temps stay at least 70F before hardening them off!
Night time temps should be in the mid 50s!
 

mr_yan

New Member
Well hardening off really was the wrong wording. Mainly I wanted the light intensity. Now is where I wish I had a window green house.

Thanks for the help. I plan on starting new seeds tonight.
 

RonsGarden

Super Moderator
Staff member
If you were aiming for a higher light intensity you can use growlights!
Hardening off seedlings is really slowly introducing them to stronger outdoor light, such as a bright shaded area to start, and then gradually move them to full sun over the span of a week!
Hardening and temperature go hand in hand so the warmer the temp outdoors the better since you had them in 90 degree temps with probably high humidity! You have to wean them off of the high humidity
 

mr_yan

New Member
Looks like I got lucky and didn't kill any.

I hope to build up a better growing area. I have a double tube four foot fixture that I have used in previos years. But i have it mounted in the cool basement. Being cool kept the plants growing slowly. This year I would like to have it in a warmer area in hopes of putting a little more size on thee plants.

I would like to have the set up in an area that gets to about the seventies when the sun hits the roof at this time of year but only falls to the low sixties at night. It's a finished attic but they never ran a new heat duct up there so it gets cooler than the 65 we heat to.

Any holes in this theory? Thanks Yan
 

RonsGarden

Super Moderator
Staff member
I use two double 4ft fixtures and enclose the area with plastic to keep the heat in as well as the humidity!
With this set up I start some of my perennials in early January! As they grow I repot them and move them to a cooler window area! In milate April they go outdoors in a bright shaded area and gradually move them to full sun.
For January and February I leave the lights on so the temp is constant 24 hours a day.
For tender annuals I start them in late April. When the seedlings are large enough to handle, I pot them up and move them to cool bright window for a week or so then move them outdoors by early May to harden off and planted out by mid to late may

For your set up you can use a propagation heat mat to keep the temps warm during the night.
 


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