It wouldn't be "true" wintersowing, because you wouldn't have the moisture from snow and rain, and the extremes of temperature changes, but I think it would work just fine. You'd just need to make sure the containers don't dry out.

Martha

Docmom gives good advice, you'll need to watch the moisture, and anything you have sown and covered with plastic or a lid will need the lid removed at the first sign of germination indoors. Where damping off isn't an issue outside, it will be in your room.

Approximately what temperature does this room keep over winter unheated? I've sown things indoors under a skylight and found that to be adequate light without supplementing with some kind of set up, but seeds for things that will germinate without chill.

If you are sowing things that require a moist chill before they will germinate, you'll need a space that will stay at a maximum temp of approximately 40F for several hours a day (or night, it can fluctuate) for a number of weeks. If you do have seeds requiring that (stratifying, and it would be some but not all perennials, shrubs, trees for the most part), you would want to provide the chill before placing in your sunroom to germinate unless this really is a room unused in winter that gets that cold at least overnight. Your refrigerator will work.

So, what are you thinking of sowing?

Edited because I realized I'd typed 'minimum' earlier when what I'd meant was maximum. Right around 40ish degrees at some point in 24 hour period and not consistently warmer.

This post was edited by morz8 on Sun, Jan 12, 14 at 16:53

As far as the wind problem, I am using milk jugs mostly and I tie the handles together in fours with twine. I have a row of tied-up jugs with other types of containers in between them. It takes care of the 'blowing away problem'.

I had the problem with wind in the past and this method seems to work.

Sowing in an unheated sunroom just wouldn't be the same. You really do need the freeze/thaw and a good snow cover helps to insulate everything.

If you can't tie the containers together, make a barricade around
the containers to keep them in place.

You can start seeds in your unheated room, although IMO it's easier to put them outside where mother Nature will take care of moisture, temps, and sunlight. Can you put your containers in milk crates or something that will keep them secured?

Last year I winter-sowed seeds of Magnolia grandiflora, which is a southern tree and marginally hardy in this area, and supposedly the seeds will die in the freezing temps of our winters. So I put the containers in the garage for the winter (spritzed the containers about 1X per month) and brought them outside in the spring. I got 3 sprouts!

I overwinter a lot of tender plants in the garage - such as tender seedlings (the little Magnolia trees are in the garage now) to mature plants like Salvia 'Black & Blue' that I dig up and overwinter in pots in the garage.

My area gets very windy, too, and I haven't had a problem with milk jugs blowing over as long as I put them on the ground -- they're pretty heavy once you put three or more inches of dirt in them.

Also very good idea about tying them together. I also put my containers in a big group and position smaller, lighter ones, like 2L bottles, inside the more stable milk jugs.