As is often discussed on the Growing from Seed forum the domes, the mini-greenhouse tops, are supposed to be removed immediately after germination. Leaving seedlings to grow under those domes prevents adequate air circulation and usually leads to damp-off and other fungal disease problems.

The purpose of the domes is only to keep the soil moist enough for germination. Even then it isn't required for any reason.

Dave

Good advice, Dave.

Jim

I leave them to sprout under the dome and at about 2 inches I take them out of the dome system to individual pots. My experience is that the dome helps having normal seedlings not the leggy ones. Because my season in zone 7 is so short I start early and when the time to take tem out they are real plants some with flowers. I am sure some of you like me are itching to start the garden fun. I already bought so much tools probably I am not going to need all of it. I bought a garden scooter with buckets for seeds fertilizers and collecting fruits and tool rack and a seat so I can set while I am working.
My woman thinks I lost my mind.

That is the way I survive the winter is to plan our garden. I just ordered pepper and tomato seeds. One of the peppers I wanted to try is already sold out.
No, you have not lost your mind!

Helen

I had that system for a while, and it served it's purpose. However, it became my opinion after a while that Jiffy pot replacements were cheaper than replacement plugs for the Park unit

"My woman thinks I lost my mind."

Ha! Welcome to the club...

I put a germinating blend in the bottom of one of those domed roasted chicken containers that you get at the grocery store. Add the seeds, sprinkle with water, put the dome on top, and place on that warm spot on the top of your refrigertor or freezer. I also make a small flat out of the Marie Callender steamer containers...keep it watered by pouring water through the hole into the bottom tray.