When to take Cover off germinated seeds?

[Germinator]

I was taught to take the cover (plastic wrap in this case) off the seed tray when the first tomato seed sprouts. But, I believe in Craig LeH.'s video, he said to put the cover back on until all seeds have germinated. The plastic wrap is hitting the top of the little seedlings now. Does anyone have the definitive answer on this? In the past, I have removed the cover after the first germinated seed comes up. I have a 1020 tray with 48 cells and about l/4 have germinated in 5 days. Greenhouse temp. is 63 but flat is holding around 85 degrees.

[Plantersville]

That is a good question. I had about half my seeds sprout when I took my plastic wrap off and havent seen anymore sprout and now have to check continuously for needing water.
Hope someone can explain it.

[Germinator]

Yes, Plantersville, you do need to keep checking for keeping the soil damp when the plastic comes off. Have you seen Craig Lehooullier's video on starting seeds in this Forum? It is very educational and something I have to refresh myself on each year. I think germination goes down when the plastic comes off and I notice that most of the germination happens when the sun comes through the greenhouse (daytime) so putting the temp up should help germination. But I hate to spend the $$ on electricity.

Hope someone else has ideas how to speed up germination on uncovered trays.

[nctomatoman]

If germination in a flat is really spotty, I've gone to cutting small pieces of saran wrap to cover individual cells or strips of cells, to allow those that have grown to get air and lose the covering.

I've also noticed that if you get seed coat stickies, leaving under plastic for a bit maintains moisture and helps to allow the seedlings to shed them better.

[Germinator]

Thanks for this info nctomatoman. Before I read your reply, I did just that, using scotch tape to hold down the plastic wrap. I noticed that the middle germinated but not around the edges, probably because heat mats were warmer in the middle and the colder air around the edges makes germination slower.

I have a new question of you. Are the fans needed because of the heat coming from fluorescent lights or to make the seedlings strong? If one uses LED lights, do you still need to have fans on the seedlings?? I am using both types of lights this year.

[nctomatoman]

I've never used fans on my seedlings - they move from under lights to getting direct sun (slowly, of course, letting them adjust) - to any needed toughness comes from their time when they are outdoors.