Tony, I don't think it's a matter of 'won't' answer your questions, more like can't if no one there has tried running a space heater outdoors in the way you are proposing. I'm sure you didn't mean for anyone to try to guess at what your results might be.

I'd be a little concerned about running a space heater in a small plastic enclosure myself.

Did you read through the FAQs here to see that this forum sows in covered containers outdoors without heat? That might be another option for you, certainly less expensive :)

I have a mini greenhouse, with a few small shelves. (It used to have a plastic zip cover, before my puppies managed to tear it up.)

Last year, I started plants in winter sowing containers, as described in the FAQ's. As some of my plants got bigger, I took them out, transplanted them in pots, and put them in the zippered greenhouse. Even, with no heat, the plants stayed pretty warm and protected in there. My plants made it through mild freezes in there, although a hard freeze would be too much. A lot of times during the day, I had to open up the zipper, as the sun was making it too warm inside.

I agree with Morz8 it could be dangerous to have a heater inside a greenhouse that size. I would think you could just bring your plants in for a night or two, if it's much below freezing. I would encourage you to read up on winter sowing though, as it's been successful for me.

Space heaters are generally meant for indoors, and anything not approved for outdoor use, which utilizes electricity, sounds dangerous. So does a space heater inclosed in plastic. My indoor space heater instructions includes caution to assure that airflow around the unit is good.

Karen

I don't think this really applies to this forum but the folks over in Growing From Seed told me to post here. I stlll think it applies to that forum but if they won't answer my questions then what can I do.

It most definitely was NOT a matter of refusing to answer your question and I am sorry you choose to take our efforts that way. Instead of trying to discuss it with us you just accused us of not even reading your post.

It was our attempt to direct you to the forum where your "idea", minus the use of the space heater, has already been tried, tested, and proven to work. You want to start seeds outside using natural light - that is not the focus of the Growing from Seed forum. It is Winter Sowing at its most basic which is why 2 of us directed you here for help.

But you made it clear that you do not understand how Winter Sowing works so I suggested you check out the FAQ's here for a great deal of good info before ruling it out.

As the others have said, space heaters are dangerous to use outside, especially in a self-contained small environment, and as I pointed out on the other forum, very expensive. But if you wish to skip either of the tried and proven methods of starting seeds (inside under lights using heat mats or Winter Sowing outside) and try your approach by all means do so.

Good luck.

Dave

Hi,

I've worked construction and during cold weather we built plastic covered structures around places we poured concrete. We heated them with propane space heaters. It's a very common practice. It's just important that your structure is sturdy so it won't get blown down. Heating greenhouses is also very common.

Hatchjon, you may be overestimating the size of the tiered mini greenhouses. A propane heater would make a puddle of most in very short order.

Here is a link that might be useful: Example commonly found mini

Have you tried putting your min/max temp sensor outside in the mini greenhouse just to check how cold it is getting in there at night?
I'm not sure what your low temps are now but I would suspect based on your zone that we are closing in on warmer temps. You may find you don't even need to worry about heat.
You could always sprout the seeds in the house and then moved them out to the mini-greenhouse. Typically germination requires higher temperatures than the seedling growing.

To heat inside a mini-greenhouse I've used a common utility extension cord/lightbulb. My husband uses it to see better while working under the hood of the car. I haven't used the mini-greenhouse at all since I started winter sowing, that's except to sit the cat food on to keep the Beagle dog from eating it. But it worked very well. It was for annuals that freezing temps would have killed. I hung the light from the lowest bar and left it unzipped because when checking the temp it was getting too warm. I just wanted to keep them alive thru the night and let nature take back over the next day.

Tony,

Some of the seeds on your list do survive freezing temps, outside, in milk jugs without blinking. I've sown Foxglove and snapdragons in December, had germination (in jugs, outside, with no heat source) in December and the seedlings survived temps down into the teens for several nights in a row in the months that followed.

I can't vouch for zinnias or cosmos as I direct seed them in the spring and allow them to come up where they may. But even those, I would start putting outside in jugs (outside, without heat) in my zone now if I wanted more control over where they grow.

I personally would not waste the electricity to keep seeds or seedlings warm. Winter sowing does work and it works quite well without putting a hole in my wallet or using up man made and/or fossil fuel energy.