Sheesh - I'm 8b and you're way warmer already than we are, especially at night.

It's going to get warmer than the outdoor air in your covered flats. Hopefully you haven't sown anything that would germinate best at lower than 80 - you don't say which type plants. You're right in guessing that your seedlings will grow better in natural light than in a window.

You're going to have to be careful to remove the covers when the first seedlings sprout so as not to cook them, and your trays will dry out more quickly uncovered. Are you home to keep them moist in a SW exposure?

Thanks for the reply! :)

Yes, I'm an at home mom, so I'm home to keep a watchful eye on them. I planted a variety of seeds, here's the breakdown...one flat of zinnias, one flat of cosmos, and two other flats that have a mix of echinacea, coreopsis, lavendar, fleabane, shasta daisies, cupid's dart, and petunias. Do you think these particular seeds can germinate if the outdoor temps are in the 80s? According the the packages, if all of these seeds are sown directly in the ground, it's not supposed to be until all danger of frost has passed...is that a good indicator of the temperature they need to be at to germinate?

So to be sure I understand, are you saying that if I put them out on the deck I should leave the cover on until they germinate and then remove the cover so they don't fry? Should I put the cover back on at night? I'm thinking that seedlings in flats will get colder faster than seedlings in the ground would get because of the shallow, exposed trays. That side of the house doesn't get sun until later in the morning so I would have plenty of time to remove the covers before the sun shines directly on the deck.

check out winter sowing forum FAQ and if anything not clear- ask away.
You are interested in doing exactly what winter sowing does with great success. Keep your trays outside in semi shade and take off lid when you see germination. Keep tray moist but not wet. If you worry too much you can take them in for the coldest night but otherwise excluding zinnias rest will be fine even with cooler temps.

I think your warmer temperatures will be fine for everything you've mentioned. Ideally, echinacea would germinate best at about 70ish, but a temperature drop at night should make your plan work

I started seeds yesterday (basil, parsley, thyme and chives) with my daughter and I just put them in the trays on the back deck with no cover (I just don't want to have to worry about removing it and my nights might be a little warmer than yours). They should germinate just fine. Like everyone said, be careful to take the top off when you start seeing germination or when the sun is shining. The humidity will cause the new plants to "damp off" which is so sad after you have gotten them to germinate and I cooked a ton of plants by not opening the top to my cold frame one morning (in February) when it was really sunny and warm.

My first year, I got about 50% germination and the second it improved to about 90%. It takes a season of mistakes to figure out what not to do!

Good luck.

Is this what happened to me? (I found this web site while searching for help with my fading seedlings.)

I swear I'm seriously considering never trying to start plants from seed again.

Last year, I moved into a new house. And although it has some nice, existing landscaping, a year or so left uninhabited (with only the lawns being mowed) left the garden a bit to be desired.

Soon after we moved in, I started a flat of some flower seeds. I think I ended up "cooking" them, as hinted at above. But I wasn't too bent out of shape, at the time, because we were overwhelmed with renovations and what not, and I just couldn't devote that much time or emotion to them.

But, several weeks ago, I decided to start some seeds that I really wanted in my garden (annuals I'd purchased from a nursery, last year). Being new to the whole "growing from seed" thing, I dutifully followed the instructions on the commercial flat kit. I played the role of protective mother, as best I could.

My tiny little darlings popped out sooner than expected (within just a few days of planting them). Still following the directions on the kit, I proppoed open the lid once the leaves sprouted. All seemed to be doing well.

On nice days (15-23C), I'd put the flat out in a partially sunny area during the day, then bring them in at night. I'd gently mist the flat if it looked like it was drying out.

Then, all of a sudden, the still tiny seedlings began to fade. One by one their stems would weaken, and I'd find them toppled over.

Right now, after having had a full tray of what I thought were healthy seedlings, I'm left with maybe 10% still looking viable. But I'm fully expecting them to die off, too.

It's really frustrating because I'd hoped to eventually build a small greenhouse and start all my plants myself. But with two spectacular failures, and seeing how much of my time goes into tending to the seedlings (even if they had survived), just paying the extra $1 for well-started plants from a nursery seems like a good deal to me now.

Anyone else having this much trouble getting even one plant to grow from seed?????