Starting Seeds in a Greenhouse?

Has anyone used a greenhouse in zone 7a to start seeds? I tried starting my tomatoes, peppers and eggplants in my basement last year and the flats got white mold on them. I scraped it off but the seeds took forever to germinate. Usually I set up my flats and lights in our bedroom and I don't have the mold problem there. However, this year I'm wondering if I can start them in our greenhouse instead, since it's a pain to get everything set up for only the couple of weeks before the plants get their first true leaves. After that I switch them to the greenhouse anyway. I'm not sure how well starting them in the greenhouse would work if I planted them as early as I usually do, which is in late March/early April.

My greenhouse is an 8' square Rion, and has a small heater to prevent plants from freezing, but I'd hate to think of my electric bills if I tried to keep it at 70 overnight.

I started my seeds in a GH this year, first year I had a GH.
I try and keep it at 60 over night...they say seed need 70 to sprout, my GH is at 77 right now, the sun is shinning.
I have no mold (yet). Mold can only grow where there in moisture present, I have a small fan which runs with the grow lights which run 14 hr a day.
I planted more tomatoes than I need and will have pick the strongest to plant in the garden.
Hope this helps a little.

Love Compost Tea

If you're worried about the seeds not being warm enough but you don't want to run the heater much, you could always get heat mats to put right underneath the flats. That's where you need the heat anyway, they won't mind if the surrounding air is chilly as long as they've got the bottom heat.

My greenhouse is fine in the daytime when the sun is shining; it's the nighttime I'm really worried about. I start my seeds in styrofoam containers that I bought from Gardeners' Supply a number of years ago. They have a wicking fabric that keeps the roots watered evenly, and the whole setup sits in a larger styrofoam pan which holds the water. Would a heating mat work under all of that, I wonder? If so that might be a solution. I could keep the temperature above freezing with the heater but use the mats to give the seeds the heat they need more directly. But since styrofoam is an insulator I suspect it wouldn't allow the heat to come through enough to do the trick.

Why not try a double greenhouse setup? You could then only heat your seedlings, and not the whole greenhouse. Of course you will have to watch the temp. This how I'm going to start this year.

How would you do that? Purchase a small greenhouse to put in the larger one?

I've been checking catalogues to see if I can find a set up that I could use over heat mats, but none of them seem to have the wicking component that keeps the flats watered.

You could use a cold frame, or build a frame and cover with plastic. I have not tried this, but will this year.

I'm not sure if that would get the flats up to seventy in the daytime and keep them warm enough at night, if I just used a cold frame. Sounds like it would be easier just to set up the equipment inside for the two or three weeks I'll need it before transferring the flats to the greenhouse once the plants are up.

Yeah, I'm still might start indoors. More control that wway.

Greenhouse gets to hot already. I am new at greenhouse gardening. My 10 by 30 goes from 50 degrees at night with a heater to 98 degrees on a sunny day. Ack. Have fried seedlings and now moved propogation inside under lights. I am learning as we speak from reading the forums but need to know if I can move my tomato plants out to the green house after potting or is 50 still too cold. I am running out of room under the lights.

Do you have ventilation? In your zone even in winter a greenhouse is going to get way too hot on sunny days unless you have some sort of ventilation. I have a small greenhouse and for me, opening the doors in the morning and then closing them in the evening works well, but since your GH is larger I would guess you'll need real ventilation to keep things cool enough in there during the day. As far as the tomatoes--I don't grow them, but if it was any other plant I would say 50 degrees ought to be fine, so unless there's something weird about tomatoes I think they'd be OK for the nights. I'd worry more about the 98 degree days, if the plants are still young and small that could fry them if you're not careful.

Thanks ecrane3. Yes I have a large ventilation fan but I guess I better hook it up to a thermostat in order to keep the heat down.

Yes, Hazel2, get a thermostat hooked to that vent fan! Unless you're in the greenhouse all day, every day it's a Godsend to have the GH vented automatically when needed. It was 82 degrees in my GH this sunny morning at 9 a.m.(heater kicks in @ 60 degrees, so it's a "warm" GH)). But 82 degrees is warmer than I like it (plus, I had a lot of up-potting to do), and surprising since the outside temp was 42, so I opened a roof vent. The temp dropped 4 degrees within 10 minutes, and stayed under 80 till around 10a.m. A little after 10, the thermostat opened the side vents (I've got it set that way to avoid a "sudden" rush of cold air into the GH). Between the open side vents and one open roof vent, the vent fan itself didn't come on until 11:30, when the temp had climbed back into the 80's in the GH. Outside temp was 48 gegrees at the time. All this to say:
Heat is a much greater threat than cold to plants in our zone
It can get very hot very fast on a sunny day, even in relatively cold ambient air
Unless you check it hourly, it will get away from you
"Insurance" in the form of a thermostat is a very wise investment considering the value of the plants...
But you'll still worry about whether it's working right...

My GH also get very hot some days. I'm working on an auto openers for my Roof. I modified the roof last summer so the whole side opens manually and it is very heavy. I plan to use the motor from an old ice dispenser , to open and close and some limit switched to control the motor.
Here is a picture of my GH :

http://davesgarden.com/community/forums/t/762475/

I have had a greenhouse for several years and have never started my seeds in it. I start them in the house under a light system my husband made for me. It's on the kitchen counter so I can watch it. This year I bought a dome with the planting disks in it and started seeds in them, you have to be carefull as they really dry out fast. Everyone of them came up and are getting big enough to put in larger pots now. I put tin foil over the outside of the light and can raise it on one side to check them at times. Also I always use a heated plant mat under them, and leave it on until they are ready to repot. I start my seeds at different times and this 2 foot light system works best for me and doesn't take up much room .After I repot them I put them in the greenhouse.

I start all my seeds in the greenhouse, with no problems. I do have to watch the daytime temps on a warm sunny day, though. But the vents/fan are all hooked to a thermostat which keeps the internal temp within 20 degrees of outside ambient(it can reach the high 80's, but this has never been a problem so far). By the time the outside air temps can't be reliably used to reduce internal greenhouse temps, all my plants are already outside (early May). I think the higher humidity in the GH trumps the temp card for starting seeds...

I should have told you where I live, I'm sure it makes a difference esp. with the mold which I never get. I live in Eastern Washington and it gets really cold here in the winter, We don't get heavy snow every year but did this year, probably six feet over all. I don't plant out until June and I have raised beds now. I save a lot of money by planting in the house instead of warming up the greenhouse. I would love to keep my GH going all winter but can't.

You're right, Ladybug! I saw "WA" and automatically figured coastal WA. I think it's safe to say that you're doing the right thing, starting your seeds in the warm house!! But for all the glorious beauty of eastern WA, I'll take the mold! Cold kills, molds just annoy...and stink!

I don't know about the mold but I really like it here. I have lots to do when I can get out. I have at least 25 deer here I feed plus wild turkey's and lot of different birds. I got a large fish aquarium this last summer enjoy it and do lots of reading and quilting. Very beautiful here even with all the snow.

You FEED deer on PURPOSE??? Now that I think about it, I probably would too if I lived up there since most of their natural forage would be covered by snow. But here in the Low Country, DEER is a true 4 letter word for gardeners! They eat anything they can get their nasty little chompers on! And they don't care how much the plants cost, or how much effort it was to plant them. They just destroy them. We don't have the benefit of snow cover to hide the plants, so a well-tended garden is a smorgasbord for them in the winter/spring. I've grown to hate Bambi!

StonoRiver, what do you do about nighttime temperatures in your greenhouse when you're starting seeds? We're in Zone 7 and I think it would still be too cold at night to keep the seeds germinating. Do you use some kind of auxiliary heat, or just let the temperatures fall? We have several large tanks of water painted black to hold heat in the GH, but I don't think they'd be enough to prevent dangerously low temperatures if it were in the 30's or 40's outside.

My nightime temps don't ever get under 60 degrees in the GH (to protect all the tropicals I raise), greenhousegal. But to compensate for the fussy tropical seeds I grow, I keep them on a heat mat under plastic covers, which can keep them above 70 degrees regardless of external GH temps. Seems to work, so far...

Still a GH newbie. I have beds outside right now but would like to try lettuce, spinach and tomatoes in the greenhouse so I have a crop for the fall. When should I start the seeds for that? I'm in Ark. and its pretty hot July and August, and I guess it could be in Sept too the way the weather has been allover the map. Any tips ? Nanadee