How soon should I put a seedling under my grow light?

I ordered my seeds on March 31st and they arrived today, I am stoked! My light should arrive on Wednesday so I am going to go ahead and start germinating a seed. The grow light I chose is the HLG 260W QB V2 rspec. Once the plant appears above the soil should I put it under the grow light right away? Should I dim it until a certain point of growth? Thanks.

Good choice for a light. I would turn it all of the way down for a seedling and put it at least 30 inches above. Once your girls spring a couple of sets of serrated leaves you can start turning the light back up.

So I should turn it up gradually over a week or so? You end up answering most of my posts no matter what question I ask. You da man! Or woman, lol.

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Leave it down until your plant grows a little.

Right now I have just one PCB of an HLG 260 V2 Rspec on this plant. That one panel is 24" away and is still turned all the way down. I probably won’t turn it up for another week or so.

Young seedlings need even less light.


Got it. Thanks.

Just watch that the seedling is not stretching excessively; at which point you can drop the light down closer. These lights do an exceptional job of growing cannabis with about half the power of everything else.


Thanks. This light seemed to be a good choice after a ton of research.

Good point. @smokysmurf you can see that these girls are getting plenty of light in that they are compact and the space between the nodes in very minimal.

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I put my seedlings in a humidity dome after they sprout for 7days, then directly under a 600w MH @24" no problem.
Then when they go to flower, they go under a 660w diy led @24"

My seed poked through the soil after about 36 hours. Can I let a seedling dry out once it has sprouted or does it have to stay moist? I can use a spray bottle to keep the top layer of soil moist or I can water from the bottom since it is in a clay pot with saucer under it. Or I can do both.

Put a dome over it (a pop bottle cut in half works fine) and mist inside the dome a couple of times a day. If you do water it, then don’t add more than a ml or 2, and wait until the soil dries before you add more.

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I found a V8 bottle that fits ok but it has a small gap in one spot. I assume the dome should not be airtight as the seedling needs oxygen? Thanks.

A small hole here and there doesn’t hurt anything. A seedling won’t consume much CO2, so there’s not a whole lot to worry about since you are picking it up to mist inside of it a couple of times a day. So long as it is clear you’ll be okay.

Just to clarify are you saying I should mist the inside of the dome itself instead of the soil and seedling?

Yes. I usually add ml of water or 2 every couple of days to the base of the plant. When it puts up a couple of nodes you can remove the dome and start watering it.

How big are your seedlings at this point? Picture?

The seedling just broke through the soil this morning so no leaves or anything yet.

She needs very little water at this point.

Me again. :rofl:

I just turned the light up on 2 young plants that had posted 4 nodes. Seedlings need very little light. Monitor the stretch of your seedlings for space between nodes to judge whether or not you are giving them enough light. A low wattage CFL is plenty for at least another week or 2.

Your soil looks wet. Let it dry out.

This is definitely rich soil. It is damp to the touch. I watered the soil a few hours before I planted and have only misted the surface since then.

I have the HLG 260 turned down to the lowest setting at 24" above the top of the pot.

How many hours of light should a seedling be getting?