IÂve wrestled with this idea every year that I put out pots into an unheated greenhouse. The seeds, sown in Promix and some in vermiculite, have no snow cover, just their plastic bags. I choose mostly those seeds that need a cold period; some (seeds) actually need a freeze to stimulate the embryo into action. With hybrid seeds, it a guessing game.
The seeds that are closer to the half hardy annual types I wait for March 1st. But for some that might be too late.

So far I have + or - 50 pots outside in temperatures so far that have seen Â6 to +12 Celsius degrees until last evening when temps dipped to Â13C. I hope that the seeds have been acclimatized and have taken up water by now. (Actually I keep sown pots inside for two or three days before putting them out so as to soak up water.)

I have tallied, in past years, a percentage of germination of wintersown seeds and IÂm pleased with the results of 65%. But I have to refine my technique perhaps IÂve had too much water are not enough cover or too much cover of Promix or sand.
Every year I am surprised as to what varieties will withstand cold but then again I have not tested tomatoes or petunias etc. etc. Tomatoes will sprout eventually. They do so in my garden compost!
Let us know of your results!

Very interesting experiment, Tiffy. Actually I never thought about that. I always thought that seeds had enough 'sense' to know when to 'stay put', but in reviewing my notes, I now realize that I never really sowed anything in the 'dead' of winter. I have usually started in Feb. and we have had pretty mild winters the last several years. The only 'disasters' I have had was with roses, which I planted at Winter Solstice last year (as Don had done) and NOTHING sprouted. I know that roses may be difficult, but these were Rugosas whose seeds I collected myself. So your results will be very interesting. I will soon be starting my sowing and we have had a particularly cold winter here in Ontario - the last 24 hours has thrown everything at us, and is still in progress. I am doing a little experiment myself with another gardener regarding tomatoes. I must find a way to get my tomatoes sown 'outside'and get tomatoes in a decent time frame. We'll have to compare notes.

Last year I held off until the end of February to sow. I found I had much more success with germination with the perennials and hardy annuals. From my previous experience (newbie just throwing anything out there in January), I found that most of the early sown seeds got waterlogged and rotted by March.

Kinda disappointing, because I lost a lot of 'choice' Datura seeds, (different than white..which reseed with regularity).

I've found that most of the containers I dump, covered in mould and green slime, were sown in December (solstice) and January.

Maybe it's the peculiarities of our own little spots in this huge country..I have a cold February, and wet, dark March.

I'm trying Tiff's experiment too..resowing the same seeds I've put out in January at the end of February..just to see what the germ is like come spring.

No brainer for me..the bottles furthest away from the deck are the most recently sowed. (Now that's a scientific method!) ;0)