Good question. I am anxious to know the answer. Since my glasses fog up in the GH, my guess is that we don't need to use plastic.

I don't have a green house but I have discovered in my hoop house, that if you cover the seeds, you stand a good chance of cooking them. In recent research, I have found that most seeds (for summer bloomers) germinate best at 60 to 70 degrees. If you can keep your humidity sufficient in your green house, I would not cover them.

But I suppose if you can offer the covered seeds shade in the green house, they might be alright. The first day I removed a 9-flat of seeds from a freezer bag and it was steaming, I quit covering them in the hoop house :).

Kristi

Sorry, I meant to say seeds germinate best between 70 and 80 degrees.

Kristi

I don't cover anything in the greenhouse. When it is real, real cold, I will throw a cloud cover or a row cover over them. No plastic, you will cook everything.

In my greenhouse,keeping it cool enough is a bigger problem than keeping it warm enough. We put in an exhaust fan from McCoys that has a thermostat, and it does a good job.

You will find that a shade cloth is a wonderful investment. I use my greenhouse year around, and I couldn't do it without the shade cloth. We bought a 45% cloth.

Good Luck.

Janie

I was just in a nursery that has the greenhouse open so you can walk in it, and it's just so lovely to be in a greenhouse with all those tiny little plants coming up in their tiny little pots.