Winter Sown

June 11, 2008

This year I tried winter sowing for the first time. The process was almost completely care-free and produced wonderful results. Here’s what I did:

I sowed almost all of my seeds by mid January using aluminum casserole/lasagna trays from my local grocery store (the kind with the clear plastic snap-on lids). For drainage I cut several slits in the bottom each tray. I also made several holes in the lids to allow for airflow. After preparing the trays I filled them with potting mix up to about a half inch from the top (nothing special, I used the Miracle Grow brand). I then moistened the mix and spread the seeds on top. Each tray was finished up by spreading a little more mix on top. The depth of this last layer was dependent on the seeds; some seeds don’t like to be covered because they need light to germinate. I placed the trays out in the garden in an area where they would get plenty of rain and light without getting in the way. After that, they pretty much take care of themselves!

One of the trays had Echinacea purpurea seeds I collected the previous fall. Here is what they looked like about 2 months later (early March):

The amazing thing is that even though we continued to have hard freezes through both March and April none of seedlings were bothered at all!

Once the seedlings had one or two true leaves it was time to transplant them into larger containers so they could continue growing. I had a few 4” nursery pots lying around but nowhere near enough to accommodate all of the seedlings waiting in the casserole trays. I ended up buying a pack of 200 plastic party cups (16oz I think, about $20). Of course, party cups don’t come with drainage holes so I spent quite a bit of time poking holes in the bottoms. Here’s about half a trays worth of Echinacea transplanted into the cups:

I ended up filling all 200 cups with Echinacea seedlings from a single 13×9 tray! Of course, not all of them survived to be planted in the garden but in the end about half of them did, which is still a lot. I haven’t quite figured out why so many didn’t make it but my best guess is that the drainage holes in the cups were not large enough to keep the potting mix from clogging the holes thus preventing excess moisture from passing through. The Echinacea that I transplanted into nursery pots did much better.

Here’s one of the seedlings a few days ago (about 5 months after sowing the seeds):

Here are the other plants that I attempted to start, along with notes on the outcomes:

  • Alstroemeria (Dr. Salter hybrids): successful.
  • Aquilegia (various): successful.
  • Astilbe: a couple seeds germinated (I think) but they didn’t make it.
  • Campanula medium: most were killed because I left the tray out in the hot sun.
  • Coreopsis: successful, already blooming!
  • Echinacea purpurea: successful.
  • Hemerocallis (Day Lily): successful.
  • Iberis umbellata ‘Apple Blossom’: successful, already blooming!
  • Leucanthemum (Shasta Daisy): successful.
  • Liatris: no germination.
  • Linum perenne (Flax): successful.
  • Lupine (Russell hybrids): successful.
  • Molucella laevis (Bells of Ireland): successful.
  • Monarda lambada: successful.
  • Rudbeckia fulgida ‘Goldsturm’ (Black-eyed Susan): successful.
  • Rudbeckia hirta ‘Indian Summer’: successful.
  • Salvia azurea: successful but didn’t transplant well.
  • Sedum ‘Autumn Joy’: no germination.
  • Tricyrtis hirta ‘Myazaki’: no germination.
  • Veronica spicata: many damped off in tray, the rest died after transplant.

Overall, I’m very happy with the outcome. I will definitely do some more next year. Here’s how some of the graduates are doing:

Iberis umbellata

Coreopsis spp.

Molucella laevis

Monarda lambada

Rudbeckia hirta

Salvia azurea

In terms of budget gardening this method makes a lot of sense. Taking the Echinacea as an example, I spent $0 on seeds (gathered them from the garden), about $0.50 on the tray, about $0.10 worth of potting soil, and $12 on cups. Approximately 100 plants survived transplanting (about half died) so each plant ended up costing me about 13 cents. I don’t count the time spent because I like spending time in the garden. That’s a heck of a deal considering most perennial catalogs carry E. purpurea for $5-10 each.