Two of the types of seed I am sowing this year require a cold treatment– essentially, in nature these are hardy plants that set seed in autumn and then lie dormant over the winter and sprout in earnest in spring. We can induce this by giving them a cold period.
To sow seeds this way, I prepare a light potting mix and use old deli containers– the four-croissant container from my local grocery store is the perfect one for this. I fill the bottom half with new light potting soil, water this and then sprinkle seeds across the top. I write the plant name on the lid and then keep it in the garage (which is unheated) until I see the seeds start to sprout, then I’ll bring it into a south-facing window in my house.
This year I have sown Viola Koreana- sylettas and Aconitum Carmichaelii, both from Thompson and Morgan, for a little color in my existing borders. I have long adored violets and greatly prefer real violets and their adorable foliage to the smaller annual violas (I prefer small violas to pansies– but I like them all) While I have planted these everywhere, I think Viola Koreana’s attractive foliage, which looks a lot like a cyclamen will add off-season interest to my strange violet collection.
Aconitums, as I have mentioned before, are such a great surprise in late summer– with delphinium-like foliage, their tall spires extend the spring-like feel of the garden. I suspect that they will bloom after Japanese Beetle season as well, which is crucial in my garden. Aconitums are poisonous, so don’t eat them. Obviously. Carmichaelii should be a nice deep purple.
Generally I sow seeds 8 weeks before last frost, which this year is on the Ides of March, but those with a cold treatment I like to start a bit early. Perennials can also be set out usually a bit sooner than last frost- particularly if you cover them with a cloche if foul weather threatens. Last frost in my area is traditionally on Mothers Day (but it varies year to year).