It's seed collecting time for many of us, and I'm curious what to do with seed that have to be left out for the winter. Should I store it for a few months and then plant it and put the pots out in late fall, early winter, or can I simply pot up the seed now and put them out in their winter location?
Generally speaking, I think the fresher the seed the better the germination rate. Planting seed in the Fall is a good time for most seed as it will be fresher and there is an entire winter period for stratification. When we get our seeds from the exchanges in January I find some seed such as Androsace will not germinate until early in the second spring and I suspect that it it is because it needs a warm/cold/warm cycle and a full winter of stratification.
For some seed, such as Fritillaria that is received in January it is recommended to keep it in storage until the following Fall before planting. I think it is because Frit seed need the full winter period for stratification; they germinate very early in the Spring. Presumably the seed may rot if planted in January or it may germinate too late in the spring to develop a strong enough seedling to survive the summer.
Regarding the Frit seed, David is correct. Before I knew better, I would hardly get any Frit spp. germination when I winter sowed in February here in zone 4. In the second spring, perhaps half of the seed lots germinated. Most Fritillaria people save their NARGS frit seed in the refrigerator until early fall, and sow them then. Gosh! Thanks for reminding me. I'm late already!
I used to winter sow all my seed in Jan-Feb, and I still think that is generally the best way to go, especially if one doesn't have more exact, credible recommendations. But there is a great number of species (including alpine) that do not need pretreatment at all. Seed germination is a wonderful area of study, and there is a huge variation in germination modes, requirements, timing, growth rates, etc.
Dr. Norm Deno's monumental books on seed germination are my first and most reliable sources of information. They are no longer in print. But the books are now available free to download from the USDA National Agriculture Library here:
Seed Germination:Theory and Practice:
A condensed listing of species contained in these books can be downloaded at the Tom Clothier site here:
You might also want to look at Tom's other info from his main page:
And let's not forget the Ontario Rock Garden Society page. (Click on "Germination Guide" at the top right.):
In the last few years I have taken a cue from nature, using the lazy man's approach, and I sow seed directly in the garden shortly after harvesting. Items like Frits, Tulipa, and Crocus, where I had miserable results in small seed pots, come up like grass when sown directly in the garden. This has also worked very well for Trillium seed. I call this the overworked working man's approach, as I had zero time to monitor or coddle seedlings in pots, most often my seedlings dying from neglect, but seed sown in situ in a prepared bed (no matter how small the prepped area is), or literally just scratched in, has resulted in phenomenal results in most cases. Here are two photographs of Frit seedlings (when I'm looking to increase or bulk up existing species in the garden, I don't always label them, but these seedlings are either F. pudica or F. crassifolia kurdica).
This year I had very good results sowing Himalayan and Chilean seeds late summer (August) (The seeds are stored at least 1/2 year in the fridge - I hadn't time to sow when I got them.) Then they sprout like cress. Normally I sow in Dec/Jan to stratify but I never get that germination rate then.
Shortly we'll be ordering our seeds from NARGS, and the European lists are out, and Rocky Mountain Rare Plants has issued it's last catalog, and Alan Bradshaw will soon have his 2010 seed-list out, so we all need to know how to handle this situation. Do we plant out the seeds immediately? Do we wait until the snows fall? January? February? Which ones should be plant indoors under lights? Help?