Celtic,
I think winter sow can mean a few things; I primarily grow vegetables and find that if I leave a few lettuce plants to go to seed I will have really early lettuce in my beds. Also, I have sprinkled spinach and mache seeds in late Fall for Spring crops. Other tricks include using lidded containers to set out seeds that need stratification (exposure to freezing) such as many flower varieties. I think that there's actually a 'winter sow' forum on here (surprise, surprise, this place is harder to navigate than a corn maze.) I intend to try the container trick on some Alpine Strawberry seeds, as I've always wanted to grow them.

Yes, there are a couple of winter sowing forums on here, the original one and the Canadian one. There's also the "mother" forum, wintersown.org (Trudy Davidoff's site).

Lois, you're probably talking about winter sowing in containers, right? If you go to the main WS forum, there's a list of FAQs and some How-tos - should probably answer your questions. I've had mixed results with winter sowing, but good enough that it's something i'll continue to do.

This was my first year wintersowing. My methods were modified from pure winter sowing in that I used regular garden flats in an unheated greenhouse. From about late April I had 400 litres of water in the greenhouse that kept the temperature from going below 0 C. Most of the seed I used was old and I expect that was part of my variable results.

Hardy perennials and annuals that self seed should do reasonably well. The problem you will have to deal with is less hardy (frost sensitive) plants that germinate before the last frost date -- they will freeze. The containers are mini-greenhouses and will prompt germination before seeds planted in the ground. Without the water, my greenhouse matched outside lows, well under 0 C. Even with lows of 0 C, I lost one batch of sub arctic plenty that sprouted just in time for a cold snap.

Plants that got planted (still lost some) four o'clock, marigold, alysum, stocks, tomatoes, hubbard squash, morning glory, scarlet runner beans, and watermelon. Not all of these did well after transplanting.

I'm increasing my plantings (mainly of successful plants) next spring. This year I didn't plant any more than I would buy forgetting the cost of more ws plants is negligible. Wintersowing is certainly worth trying.

I do the perennials earlier and the frost-hardy annuals later, like in April. That's the trick. I don't bother doing tomatoes, or flowers like petunias and impatiens - those i start inside. For true winter-sowing, you leave the containers outside in all weather, and that's what makes the plants tougher. If they are in their mini-greenhouses when a frost strikes, most of them will be okay, though i have lost some things that i planted too early. Some years, i've put the containers of less hardy plants into my cold frame for protection. Purists wouldn't think this was a good idea, but they don't live in zone 3 - we have to adapt!

Thanks for all your ideas it definitly gives me food for thought. I've put seeds in pots with a light soil mixture and lightly covered the seeds and then potted the pot in the ground( some of these I've left(forgotten) for a year or two and ended up with good results. When the ground freezes I cover the area with straw.

You're right that the seeds I've done needed stratification-eg.delphs I've also left lettuce to self seed along with a variety of plants. I asume those of you that do more sensitive plants have a greenhouse to put the spring seedings into.

Hope to use some of these ideas at the next place.
Take care Lois