Running lights overnight during cold treatment

Csross · March 30, 2017

For the past few years, I've just started a few seeds under a desk lamp in front of a sunny window. Thanks to all of you enablers, though, I'm now starting a bunch of different varieties of tomatoes and other vegetables for everyone I know, and I've run out of space. So I'm looking to move my setup into the garage under florescent shop lights, and I've got a question about temperatures.

Last night it got down to 36F outside, but the shelf in my garage where I want to start seeds is on an interior wall and only went down to 48F. Based on what I’ve read, that still seems ok. I was thinking, though, since there’s no natural light in there, I could run the lights overnight and have them dark during the day, which would keep them a bit warmer and give me a little cushion if we get another colder night. Would that screw up their ‘diurnal rhythm,’ or isn’t that a concern with plants? I’ve got a timer and was planning on running the lights for 14 hours per day. (Just regular Home Depot florescents, 6500K, 2700 lumens)

Right now, the tomato plants have the cotyledons fully unfurled, but haven’t started their first true leaves yet. The lettuce, bok choi, etc, were started earlier and have their first true leaves out. The garage will probably get down to 46F at night, up to 60+F during day depending on weather. I’ve read that cold treatment should last 2 weeks, but I assume that’s a minimum? I plan on leaving them there until I start hardening them off for planting. Plant out is generally in early May, but I’m hopeful it’ll be a bit earlier this year due to the warm spring we’ve been having.

Does running the lights overnight make sense? Anything else I need to be doing? Thanks!
-Chris

March 30, 2017	#1
Csross Tomatovillian™ Join Date: Jan 2014 Location: Bel Air, MD Posts: 28	Running lights overnight during cold treatment For the past few years, I've just started a few seeds under a desk lamp in front of a sunny window. Thanks to all of you enablers, though, I'm now starting a bunch of different varieties of tomatoes and other vegetables for everyone I know, and I've run out of space. So I'm looking to move my setup into the garage under florescent shop lights, and I've got a question about temperatures. Last night it got down to 36F outside, but the shelf in my garage where I want to start seeds is on an interior wall and only went down to 48F. Based on what I’ve read, that still seems ok. I was thinking, though, since there’s no natural light in there, I could run the lights overnight and have them dark during the day, which would keep them a bit warmer and give me a little cushion if we get another colder night. Would that screw up their ‘diurnal rhythm,’ or isn’t that a concern with plants? I’ve got a timer and was planning on running the lights for 14 hours per day. (Just regular Home Depot florescents, 6500K, 2700 lumens) Right now, the tomato plants have the cotyledons fully unfurled, but haven’t started their first true leaves yet. The lettuce, bok choi, etc, were started earlier and have their first true leaves out. The garage will probably get down to 46F at night, up to 60+F during day depending on weather. I’ve read that cold treatment should last 2 weeks, but I assume that’s a minimum? I plan on leaving them there until I start hardening them off for planting. Plant out is generally in early May, but I’m hopeful it’ll be a bit earlier this year due to the warm spring we’ve been having. Does running the lights overnight make sense? Anything else I need to be doing? Thanks! -Chris