Curious about many seeds I started six days ago. I built this seed starting greenhouse trying to improve my seed germinating. Outdoor temps will probably hit freezing the next few nights. The area is well protected and gets quite a bit of radiant heat from the gravel driveway and stone foundation during the day. Does a few cold nights have an effect on germination? Seems it wouldn't as I've heard many success stories with winter sowing. Am I worried about nuttin?
[quote="kdfisher"]Curious about many seeds I started six days ago . . . Does a few cold nights have an effect on germination?
Temperature definitely effects germination. At a minimum you'll have to add the cold days to the germination time. A lot of it depends on what you planted. For example: Last year my pepper seeds at 65 degrees took 3 weeks on the average to germinate and many wouldn't germinate at all. This year in the 75 to 85 range they took around six days with a much bigger number actually sprouting.
What I'd do is put a light in there to provide some heat and cover it up with something for insulation at night to protect it. I'd start early this evening so that you can check on it hourly so you have some idea if you've over done the heat and insulation.
I wouldn't worry about it. Like you said radiant heat will keep the temperatures above freezing. It is amazing how much heat the gravel and wall will retain. If you wanted to keep the temps a little higher, throw a sheet or two over it once the sun goes down. Another thing that works real well for me is to keep a few jugs of water in my coldframe. They warm up during the day and keep temps 5-10 degrees above ambient at night. Your germination may take a few extra days with the cooler temps, but they won't freeze unless you are expecting temps in the low 20's.
The light idea is great but I'm concerned about condensation droplets falling from the top. I surely don't want a short and potential fire..or is that an urban myth? The same is true with a small space heater I bought for another area (pic) I keep some Coleus in. I run it only in the morning. I suppose I could put a roof over it. This morning outdoor temps at 38 degrees with the small seed house at 46 degrees. The jugs sound like a great idea, plus an old blanket will help out.
Water dripping on a light bulb isn't directly a shorting problem. The problem is the same with any hot glass that is cooled in one spot suddenly, it breaks. What I use in all these situations is Christmas lights. I've used a string of the little lights to keep all kinds of things warm. They are made to go outside and are cheap.
Taking it to be about 30' x 42" x 24' it has about 35 sq foot of area. Assuming it's R value is the same a a single pane window it will take 700 btu/ hour to keep it 20 degrees above ambient which equals 200 watts. That sounds high to me. throwing a blanket over it at night would reduce that a lot.
How about one of those "coffee mug warming coasters"? They never get very hot to the touch, and probably are sealed against water. Probably only 20-50 watts, so I agree that a blanket or even a tarp would help a little heat energy create a greater temperature difference.
Or, before it gets so cold at night that you would be "letting all the warm air out", add two gallon jugs of HOT water.
Or, if you have some of the heating tape that people wrap around pipes to prevent freezing, that's an option. But the newer kind have abuilt-in thermostat, so they would only come on as the air approaches freezing. Instead of that, you waould wnat some plain, waterproof, 2-5 Watts per foot heating tape.
If there is a danger of shorting, I would think it would be where one thing plugs into another. Wrap that in plastic film or at least drape something plastic over it.
So far so good. I actually found an old quilt I draped over the seed house. Inside temp 49 degrees with outside at 28 Thursday morning. I did have a few gallon jugs sitting in the sun all day that I put in as well. I also feel more confident about the heater. I don't know where I got the condensation problem as it stays dry with the heat and fan running. I did wrap a cord connection in duct tape..good idea. Thanks
Those Christmas light ideas sound great for next year. It could probably serve well for some kind of underside heating system.