When to add light to seedlings, even if all haven't sprouted

davidtigerfanMarch 3, 2010

Hi folks! Just a general question. I've got about 24plants that I'm starting from seed (Tomatos, cukes, peppers, etc...) and I noticed today that at least 10 of them have sprouted after only about 4 days! I've currently got them on a wicking mat that sits on a tray of water, that sits on a heating pad. For the 4 days I had this whole setup covered under a clear bin. What should I do here? Should I move them out from under the bin to the grow lights or should I wait for the rest of the seeds to sprout?



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lady_alicia Zone 5/6 PA(5)

Do the tomatoes have any "true leaves" on them yet? If they do, perhaps you could transplant those into peat pots or a separate container with potting mix and place them under the lights. Then keep doing that as the others germinate and grow sturdy enough to transplant. It's my understanding that pepper seeds need heat to germinate, so I wouldn't remove the tray from the heat.

I'm also germinating and growing under lights right now, but I haven't started my tomatoes and peppers since my growing season is a little later than yours. I'm in PA, so I won't start mine for a week or two yet. But my flowers are off to a good start! :)

I'm sure others can offer some insight and more info. Hope that helps, though!


    Bookmark   March 3, 2010 at 10:37PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

I think you'll find this issue discussed in several of the posts running here and the answer is always the same - once germinated (breaks the surface of the soil) any plant should be removed from the heat pad, out from under any cover, and placed immediately under the lights. To do otherwise only results in long leggy seedlings with weak stems, increased chances of being killed by damp-off, and potential loss of all the early plants. The only time this causes a problem is when folks try to germinate many different things in the same tray which isn't recommended so next time consider using separate containers for each variety so they can be easily separated.

If a tray contains all of the same thing - say all tomatoes or all peppers - then once any have germinated move the entire container to the lights. The rest will still come along within a couple of days or they would never have germinated anyway.

But if the tray was seeded with mixed varieties of things such as you did then all you can do is as Alicia suggested - transplant the germinated ones to different containers and move them to the light while leaving the rest covered and on the heat.

Since tomatoes, cukes and peppers all have very different germinating times so you will have to transplant out those that have already germinated.


    Bookmark   March 3, 2010 at 11:25PM
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keriann_lakegeneva(5B WI/IL border)

Ditto what Dave suggested.

It is better to remove heat too early and add light too early then the other way around, if you are wondering when to switch your seedlings from 'germinating' to 'seedling' set-ups.

Even with my flats that are all the same petunia plants, I remove the heat as soon as the first one germinates and get them under the lights, the others were soon to break soil.
Happy Gardening!


    Bookmark   March 4, 2010 at 6:42AM
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Thanks guys! I am growing in cowpots so I can separate just by cutting the germinated seedlings out. The only unusual thing is that I don't have just one variety of plant germinating. ie, I have 4 pots of cukes, but only one has germinated. I guess I'll leave the ones that haven't germinated on the pad and move out the ones that didn't. Worse comes to worse I'll just try to regerminate.

    Bookmark   March 4, 2010 at 9:14AM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Research 'pricking seedlings'. Just transplant the sprout ones that way. I know you usually read not to transplant until true leaves etc. but in truth it can be done at any time (with care) and often is and in this situation you may have to do it. ;)


Here is a link that might be useful: Pricking seedlings info and videos

    Bookmark   March 4, 2010 at 1:54PM
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Hmm, now I've noticed mold on the cowpots. Looks like the spiderweb mold as well as some sort green mold that actually looks like lichen. I've moved the pots that have sprouted out from under the container and now under lights. I'm setting up a fan next to keep them dry.

    Bookmark   March 4, 2010 at 3:48PM
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keriann_lakegeneva(5B WI/IL border)

Thats why a lot of us run away from peat pots/cow pots.

You just can't control the moisture : (.

Keep them on the dry side and your fan should help a bit. Better yet, get them into plastic or foam containers.


    Bookmark   March 4, 2010 at 10:00PM
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naturemitch(3/4 WI)

easy fix---

just have a grow light above your germinating area...no worries about stretching seedlings, or when to move.


    Bookmark   March 8, 2010 at 11:00PM
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Oops =) I did the same thing as Dave. I thought germinations of 8-14 days and 7-12 days was close enough to have in the same tray.. until those darn broccoli plants started shooting up after 3 days! Good thing I was reading up on it, I was going to just leave them where they were (small dark bathroom - it's the warmest place in the house). Unfortunately mine are in a flat so I guess I'll be transplanting them tonight =( It's my first year trying this, I'll know better for next year!


    Bookmark   March 10, 2010 at 1:45PM
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