Humidity domes are for germination only. Same goes for the heat mats - germination only. Once the seeds have germinated the domes need to be removed and the seedlings are removed from the heat mats and placed under the lights. Failing to do so leads to root rot, leggy growth, damp-off and other fungus issues.

So to answer your question, once the seeds have germinated on the heat mats, remove the dome or at least prop them well open and turn off the heat mats.

OK?

Dave

Thanks Dave -
Heat mats removed after germination. Got that part. And I'll take care to use taller (7") humidity domes which are ventilated right after germination.

I would remove the domes as well, however, I know from experience seedlings of this plant variety like high humidity, generally for the first year. Many growers float the seeds to germinate them, then transplant to their favorite medium. I lose too many in the transplanting.

My real concern was whether grow lights are used with heat mats and humidity domes at the same time (until germination) and if there is a danger of the grow lights melting the plastic domes. I'm guesing not at this point - maybe I'm being a little too cautious.

Thanks again
Mike

Using the lights with the domes and mats is only necessary when the seed variety requires light to germinate. A few flowers do but none of the average vegetables require light for germination. Otherwise the lights aren't on until after germination.

Some use the lights as an additional source of heat if their area is especially cool but when used that way they don't need to be all that close.

Dave