Last year, I was introduced to winter sowing. I hadn't heard of it before, but there was a lot of talk and excitement about it at Dave's Garden. The idea is to make a miniature greenhouse out of gallon milk jugs or other suitably-sized container by cutting the top off, putting three to four inches of soil in the bottom after poking holes for drainage, sowing your seeds, duct-taping the top back on and setting the jugs outside with the lids off, right around the time of the winter solstice (December 21). Then you forget them until spring.
WHAT?!?!?! That's crazy. Nothing will germinate and grow in the dead of winter around here. It says on most seed packets to either start the seeds inside four to six weeks before the last frost date or to not plant them outside until after last frost date. Where I live that's May 15th, nearly five months after the winter solstice. How on earth can this work, planting seeds outside in December and January?
While not all seeds are suitable for winter sowing, there are an awful lot that are. Logic started to speak to me and I thought about my garden and things that self-seed. Columbine, forget-me-nots, morning glories, petunias... Oh those petunias.
In our flower bed in front of the porch, we have vinca planted. It's been there for several years and I love the little purple flowers speckled among the robust vining foliage. Last summer, as I was walking around, weeding out the beds, I noticed something coming up that didn't quite look like a weed, but I wasn't sure what it was, so I left it. A week or so later, there were a few more, and I left those as well. Imagine my surprise when my 'weeds' bloomed! They were pink petunias! I thought someone (probably my mom) had played a trick on me and planted them there when I wasn't looking. I hadn't had any petunias in there, ever! But I did have them two summers before, in the flower boxes that were directly above.
Now when you consider the size of petunia seeds, and that they need light to germinate, the fact that ANY of them survived in the ground for two years and grew to maturity is nothing short of a miracle. There are 260,000 petunia seeds to an ounce! Open up a ripe seed pod, and you'll see the fine powder that is the seed. I had seven petunias grow and bloom in that bed last summer.
Other plants that are good for winter sowing besides those that self-seed, are those that require stratification or cold-chilling. The seed packet tells you if they need it. Stratification of seeds is where the seed is soaked by the wet soil which softens its hard outer coating and then the action of freezing and thawing will help break open the seed when it germinates. You can simulate this by using a plastic bag, some vermiculite and your refrigerator, but why not let Mother Nature do the work? When the time is right, the seeds germinate and start growing. They're already outside in a somewhat protected environment and they harden off naturally, so when it comes time to put them in the ground, they take right off.
I wouldn't have believed it if I hadn't tried it. Last year, I sowed 22 milk jugs. Out of those, about half of them did very well and the seedlings made their way into my gardens. Others were scanty and some didn't grow at all. Notes taken and lessons learned.
Today, I sowed 10 jugs and put them out. We finally are getting weather cold enough that there's no chance my seeds will germinate too early (and then freeze to death). I planted:
- Lupine 'Sunrise'
- Penstemon 'Rocky Mountain Blue'
- Malva sylvestris
- Heliopsis 'Loraine Sunshine'
- Siberian Pea Shrub
- Blackberry Lily
- Coneflower 'Kim's Knee-High'
- Coneflower 'Bright Star'
- Baptisia australis
- Crocosmia 'Lucifer'
It's 32° right now and we're under a Winter Storm Warning. Let the stratification begin!