When can plants be weaned from grow lights?

josie13March 16, 2011

Hi, I've searched these forums again and again when I have questions and have found lots of useful information in old posts. I'm sure this has been asked before but I've had a hard time locating a thread with a clear response to my question.

My first question is about how long before I can wean my plants off the grow lights, as in when they no longer need to be under the lights 16 hrs a day. My last frost date here in my area (hudson valley, NY) is April 24th. In the daytime the weather here varies between 50-65.

I just started a 2nd batch of tomato seedlings and they should germinated in a day or 2 on the mat. My first batch have been under the lights for 5 days or so, and I can see that they are just starting to develop small first true leaves. I plan to repot those when the true leaves are a bit bigger because there are 2-3 seedlings per cell.

I've read various threads on repotting- but I really am a little confused about when I should repot the tomatoes- can I repot as soon as they develop a true leaf or 2?

I have set up 2 lights, I will be getting more because I will definitely not have enough room for all these seedlings once they're re-potted. What size must they be before you can start acclimating them to less fluorescent light and more natural outdoor light?

I have started cabbage/kale/cauliflower/broccoli too- when can I wean them off the grow lights? Ack, this should be obvious but I'm just a little overwhelmed right now and I would like some advice/info from more knowledgeable seed starters.

Is hardening off the process of weaning seedlings off grow lights?

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Never, or at least not until you move them outside under sunlight. A simple analogy - when would you like to be weaned off air or food?!


    Bookmark   March 16, 2011 at 7:58PM
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taz6122(N.W. AR.6b)

Is hardening off the process of weaning seedlings off grow lights?


    Bookmark   March 16, 2011 at 11:34PM
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IMO hardening off is the process of taking plants that are soft meaning they have been growing in perfect conditions regarding shelter, moisture, light, air temperature, soil temperature, etc. and hardening (acclimating) them to the variability of real world conditions such as breezes/wind, moisture/rain, sunny/cloudy days, wide varying temperatures, variable ground soil temperatures, etc.

A non-acclimated plant that has never experienced strong air movement can be crippled or killed by planting out on a windy day as quickly as a plant that has experienced no true sunlight being planted out on a sunny day. Likewise a non-acclimated plant that has always been bottom-watered or misted will get beat down and possibly crippled by the first hard rain.

When hardening off plants a person should think about toughening up the whole plant - leaves, stems, and roots.


    Bookmark   March 23, 2011 at 12:07PM
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taz6122(N.W. AR.6b)

In this case the proper way to ween them off grow lights would be to harden them off and get them used to the sun.

    Bookmark   March 23, 2011 at 2:29PM
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