That depends somewhat on where you are, what your expected first frost date. I germinated some Hosta seeds earlier this year and while I put them out in a greenhouse of sorts, our spring was rather cold and I didn't get any germination until about late April and most are now starting to put up their 3rd and 4th leaf, it'll be transplant time soon.

With the warmer temperatures you should get fairly quick germination and I would think that in 3-4 months there should be sufficient growing left to get them to a size where with some good mulching overwintering will not be a problem.

Remember that OP Hosta seeds do not come true, you'll likely end up with naught but green seedlings, amongst which you may well find one or two seedlings worth growing on. It's fun to grow them but be prepared for serious culling and be ruthless about it. Otherwise you'll find yourself looking for space that could/should go to planting much more worthwhile Hostas.

I used the Winter Sowing method to germinate hosta seeds for two years in a row. Last year I tried some seeds from Francis William and I really like the new plants. They don't have any variegation, but the leaves are thick (like their Mama) and of a light green colour. Keepers for sure!!

These are last year's seedlings...
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