Winter sowing a deceptively simple concept. Many, many plants self seed or 'volunteer' or show up as unwanted weeds… it all depends on the context. The point is plants go to seed, the seeds hit the ground. They survive the winter and grow in the spring - robustly.
But…when left to Mother Nature, these volunteers show up willy nilly or perhaps not at all. Left to her, seeds may wash away, be overwhelmed by competition, or horror of horrors – be weeded away by the inexperienced gardener who doesn't recognize a cotyledon from a true leaf.
What to do, what to do? Take those same seeds and plant them in a miniature coldframe. Put it outside. Do this in the winter. Let them freeze. Let them thaw. Let them suffer the slings and arrows of the temperate climate. They will most often delay germination until spring rolls in. Then they will put on vigorous growth in a semi-protected environment. They will be easy to identify (if you labeled the container to start with). They won't wash away. They don't take up every horizontal surface in your home for weeks on end. They don't require artificial lighting.
Other fun things:
Flats can be started and placed outdoors throughout the winter. No need to concentrate your efforts in one rushed time period. Also, this gives the winter weary gardener a chance to play in the mud in the deep dark and depressing days of dark, dark, dark. Did I mention dark? Something about planting and having a real reason to go outdoors seems to lighten the dark.
Flats can be recycled from almost anything…carry out food containers, big plastic jars, pots and zip lock bags. As a new container with potential shows up, one can dig out a packet of seeds and have at it. No need for huge preparation or back aches from tedious duplication of precision planting. Just add dirt, water, drainage holes and seeds then take a little walk to the frozen garden. Leave it to powers that be. It will usually work.
What kind of plants can be winter sown?
A non exhaustive list:
Tomatoes: Yup, those little nightshades we treat so tenderly under the grow lights spring up like the wild ones they really are when a rotten fruit falls to the ground. If the plant 'volunteers' or forms weeds it can be winter sown.
If the plant lives year to year it survives winter. If the plant survives winter so will the seed.
Same as perennial, if it lives over the winter it is appropriate for winter sowing.
The fact that the plant dies is not only because of winter, it is often just its natural life cycle to make seeds then die. Many seeds of annuals are appropriate for winter sowing. If unsure, research it. If the plant originated in a temperate climate it likely can be winter sown … or just experiment. Pumpkins work.
Remember, if it volunteers it can be winter sown.
Reading on the many, many sites found by googling 'winter sowing'
(an excellent FAQ)
OK, this is so sad. I just wrote this node again, 14 months later. I forgot I wrote it before. I'm leaving this here for my own amusement.
Volunteer plants seem to survive the winter. You know those purple cone flowers that show up where you know you didn't plant them? or the volunteer tomatoes for that matter. They don't need coddling with indoor heat and artificial lights to grow. The problem is however that they come up along with the poison ivy and the chickweed. OK, some of us like chickweed but that isn't my point. My point is the plants we want, the ones we define as Not-Weeds because we like them, well it is difficult to know just which ones they are when they are little seedlings. So, although they will grow when planted in the fall directly outdoors they may not survive the "weeding" process. They also may not survive the competition from more vigorous plants, weed or not.
So, this lady, Trudi Davidoff, came up with a system...so intuitive yet genius. She calls it "winter sowing".
The basic idea is to plant those seeds that can survive and thrive an outdoor winter in containers that give them some degree of protection from the elements and the competition and allows them to be identified as "valuable".
She recommends using a free and recyclable containers that prepared food is packaged in, things like the thick plastic black bottomed dishes with clear snap on lids one takes home as a "doggy bag" these days.
Make a few drainage holes, sow your seeds thickly in commercial potting soil (less damping off of the seedlings), place the lid with some air holes on it and put outside. Do all this after freezing weather has commenced so the seeds don't germinate until spring.
Each container will have a single type of plant growing it. When it is warm again plant little hunks of the seedlings where you want them.
No muss, no fuss.