By Trudi Davidoff
About ten years ago, I began sowing seeds outdoors in winter as a practical solution to a problem I had, which was lots of seeds and no place to sow them. An avid seed trader, I visited seed trading forums and exchanged open-pollinated seed saved from my own garden for other people’s offerings. Seed traders are often generous folk and send an extra bonus packet or two along with what’s been agreed upon, and in a few months’ time I had enough accumulated to fill a popcorn tin. There were annuals and perennials, shrub seed, grasses, vines, veggies and herbs too. It was wonderful, except that I live in a cottage and don’t have room for an indoor light set-up, and the cat owns the windowsills so there can be no trays of soil and sprouting seeds there to be warmed by streaming sunlight.
Then one day I was out on my patio just about stomping my feet in frustration when I had a thought: Mother Nature sows her seeds outside in winter, and I could do the same. But I also knew that direct sowing had iffy results because the seeds could be eaten by birds, bugs and critters, wash out in a storm or dry up and fail to sprout. I could sow the seed into containers instead of direct sowing. I was a new homeowner then and like any new homeowner I didn’t have two nickels to rub together, so I could not afford new nice special sowing containers. I was going to have to rough it and scrounge and make do with what I had on hand, which was lots of recyclable kitchen containers in my green bin. I would make my sowing containers from milk jugs, takeout containers, soda bottles, or plastic clamshells that held salad or cookies; I could be imaginative, creative, save some bucks because I’m not buying the containers, and experience that good feeling of getting a second use out of something that was being taken to the curb for collection.
Here’s how it works: Seeds are sown into vented containers that are placed outside in winter; they will experience everything that seed sown naturally, dropped from plants or blown in on the breeze, will experience. They get rain, snow, sleet, wind, hail and lots of sunshine too. But these seeds are protected from the environment. The lids shield them from downpours that could dislodge them and the vented lids let in some rain or melting snow to keep the soil moist and just as important—they allow air that has been warmed by the sun to escape. Winter sowing containers are like mini-greenhouses or cold frames.
Here we are working with seeds from temperate climates—regions with distinct different seasons—spring, summer, autumn and winter. The method does not work with plants from tropical regions that are steadily warm or hot. It’s easy to choose what to sow: Often a common plant name will include an environment or climate from the natural world—these are all good plants for winter sowing. Some names include brook, canyon, field, lake, meadow, mountain, plains, prairie, river, valley, etc. Some examples are: bog laurel, queen of the meadow, streambank fleabane, marsh mallow, mountain larkspur, plains coreopsis, prairie clover, and river birch. Some names might include locations from temperate climates like: alpine, American, Canadian, Chinese, polar, and Siberian. Some examples are: Arctic daisy, alpine aster, American star thistle, Chinese wisteria, German iris, Japanese maple, Oriental lily, polar willow and Russian olive. Seed packets, catalogs and websites often include plant habit and germination advice—words to look for indicating a variety could be good for winter sowing might include: Pre-chilling—freeze, refrigerate or stratify for any amount of days, will colonize, self-sows, reseeds, sow outdoors in late autumn, sow outdoors in early spring while nights are still cool, sow outdoors in early spring will frosts may still occur, hardy seeds, seedlings can withstand frost, can be direct sown early, wildflower or weed; the plant name itself could contain weed, such as butterfly weed, Joe Pye weed or jewel weed. Take a walk around your own garden and neighborhood, visit a local botanical garden and see what plants seem to be reseeding in the wilder unkempt areas. If a plant reseeds in your garden then you can try that species with winter sowing. Plants that reseed in wild areas as well as regional wildflowers are all good choices.
For flats I like to choose containers that will hold at least three inches of soil in their base, as shallower containers can dry out too quickly from strong sun or breezy days. My favorite flats are foil take-out pans with clear plastic lids, whipped topping containers, two-liter soda bottles and clear or translucent gallon jugs that held milk, juice or water. I’ll mention at this time that I choose to sow all my veggie and herb seeds in containers that already held food—I know that this material is safe for food; I don’t want concerns about toxins from unsafe plastics leaching into the container soil and being taken up by the roots of the seedlings. For ornamental plants that won’t be eaten I am not so worried and will sow seed in whatever is on hand that I can make into a container.
When preparing a foil base container I wash it well in hot soapy water and rinse well. I take a small paring knife and pierce the corners near the base to make some drainage slits. All containers need drainage or seeds can sit in muddy soil and rot–rotted seeds won’t sprout. I turn over the container, wipe it dry with a towel, and on the bottom I add piece of duct tape long enough to write the name of the seeds I’m sowing in that container, I use an industrial strength waterproof marker to write the name. I like a label on the bottom because under the container it can’t be bleached out by the sun. Add some soil to the container filling to about an inch from the rim, moisten with water—I like to sow at my kitchen sink and use the sprayer to gently water the soil in the container. You want the soil to be moist but not muddy, then let any excess moisture drain away. Sprinkle the seeds over the top of the soil, spacing as best suited, and gently rub or push into the moist soil until they are just covered. For the lid, take the paring knife and add a few slits to the top of the container—about once every four or five inches. These slits will vent away heat and let in rain and fresh air. Put the lid on the container, secure it around the sides with duct or strong packing tape and place it outside in safe location where it will stay for the winter until warmer days come and the container germinates.
For whipped topping tubs, use a sharp paring knife and poke three or four drainage slits into the bottom of the tub, add a label to the bottom of the tub, add soil to about an inch from the top, moisten the soil, then sow the seeds. Use the knife and poke a small hole in the center of the lid. Then take scissors and entering at that small hole cut out the center of the lid, leaving about an inch inside the rim. Place a piece of clear plastic wrap over the sown tub, snap on the lid which will tightly hold the plastic wrap in place. Take the knife and add a few slits to the plastic wrap for ventilation.
With gallon jugs and soda bottles, cut around the middle of the container almost all the way through without severing top from bottom. Add drainage slits, label the bottom, fold back the top, add soil, moisten and sow with seed. To close the container fold the top back into place and secure with duct or strong packing tape. Remove and discard the cap. The spout of the bottle vents away sun-heated air and will let in moisture and fresh air. Looking through the spout of the bottle is a great way to check on soil and seedlings after they emerge. You will find it very exciting to peer in and see your first green seedlings. Though I’ve been winter sowing for many years, it still thrills me when I see the first sprouts of the season.
Outside, the seeds are protected in their flats. The lids keep birds and critters out of the soil, in a heavy downpour the lids will soften the brunt of it and the seeds won’t be dislodged and washed away in a deluge. Any seeds that have been loosened often are floated to the sides of the container and will survive to sprout near the edges. Throughout most of the winter the soil is frozen and you don’t have to worry about it drying out, and when weather warms and there is a thaw you can check for soil moisture. Remove a lid and look at the soil—dry soil looks like brownie mix just out of the box and is light in color, and moist soil looks more like prepared brownie mix about to go into the oven.
When my dog was young I couldn’t place a container on the ground in the yard or she would think it was a toy, grab it, shake and destroy it. I had to keep the containers on the picnic table where she couldn’t reach them—they were safe up there. As the years went by the dog didn’t bother the flats anymore and I put them on the ground again but my son and his college friends would come home late at night and stumble over the containers as they made their way through the yard. And, if well hidden under snow, the containers could be mangled by my husband or me when we are digging out from a bad snow storm. I know my own yard best—I have to keep the containers up off the ground. If your yard is safe from dogs, big boots or snow blowers then your containers will be safe on the ground. Otherwise, get them up onto a table where they will safely pass through the season without being disturbed by dogs, critters and people.
Close to the end of winter season you may begin to see the first of the seedlings. Typically, those that sprout early are hardy annuals or perennials that remain semi-evergreen in winter; cold-season veggies sprout early too. Look for alyssum, centaurea, dianthus, malva, pansies, rudbeckia and violas to be among the first flowers and cabbage family, onions, chard and spinach to be some of the earliest sprouting vegetables. Germination in any flat can be staggered as not all seedlings germinate on the same day or even the same week. My picnic table gets nearly full sun during winter and in spring; when the sweet gum above it begins to leaf out, the table gets filtered shade. The filtered shade, especially at midday when the sun is strong, helps keep direct overhead sunlight from burning new seedlings, and I don’t need to water the flats often. The more sun that shines on the flats the more soil evaporation you get. When I cannot be home to mind the flats I move all of them into shade and also set up a sprinkler attached to a spigot timer and water the flats during midday, this way I don’t have to worry about them drying out in hot mid-spring sun or making arrangements to have someone reliable come by and water my seedlings. Sometimes after germination the weather turns bitter and a frost is predicted. I don’t worry about seedlings of hardy annuals and perennials but tender annuals can be nipped by a frost. I can move the seedlings to an unheated room or the trunk of my car for the time the frost is predicted, or I can drape an old comforter over the flats and remove it the next morning. I do not bring sprouted flats into a warm house—the warmth fosters fast top growth which may not be as cold hardy as the seedlings that sprouted outside in early spring weather. If you must protect your seedlings give them tough love, no coddling. Sometimes a few seedlings will falter and die, but those that survive grow on to be hardy plants.
Transplanting should be done while seedlings are still small, usually less than an inch tall. I do not thin out flats but instead pry out an inch hunk of soil and seedlings, taking care not to tear roots, and plant this hunk into a prepared bed, spacing the hunks about every six inches or so. I let Ma Nature thin out the weakest seedlings on her own as the little plants grow and fill out. This hunk-o-seedlings method works great with wildflower blends that grow and flower together to create a natural border. Or sow a few packs of annual alyssum into a large flat, and then divide the seedlings into dozens of inch hunks to make an easy and inexpensive edging for your borders. After the seeds begin to sprout I increase the lid vents a bit to help get them used to more fresh air each week. Winter sown seedlings don’t grow very quickly above the soil, but they develop wonderful roots, and do grow quickly once planted in the ground. With the winter sowing method you can grow zillions of climate-ready seedlings—they are tough, have great roots and survive cold spring soil better than purchased transplants.
I usually begin my winter sowing around December 21st and I continue sowing flats throughout winter, only stopping when the weather is so warm at night I no longer need a jacket, and usually by that time I am already transplanting my earliest sprouts. I like to plant out the flats a few weeks after they sprout, getting the seedlings established with light watering and taper off as I begin to see new growth. Seedlings should be fed lightly at transplant and then increase feeding strength as they grow.
Winter Solstice in usually on December 21st and it marks the shortest day of the year. Solstice sowing is a meaningful ceremony you can participate in by sowing seeds that represent remembrance, life, Mother Nature, and faith. Seeds of remembrance should be seeds of flowers that remind us of someone we knew and loved but is now gone from our lives forever. Seeds of life should be seeds of plants that make fruit or nectar and invite birds and butterflies to our gardens. Seeds of trees should be sown to honor Mother Nature. Seeds of Faith can be seeds for plants from a zone that is beyond our own in warmth. It will help us to remember that we accept in our hearts that Ma Nature is capable of miracles. I live in zone seven and will “Solstice Sow” seeds of plants that are hardy to zone eight.
I encourage you to give winter sowing a try. Cautious beginners should try wildflowers and cold-hardy veggies their first season—these are usually easy and successful choices. The method is adaptable. Make containers with what you have on hand, use your favorite sowing medium, sow seeds of plants that thrive in your own region—the cost of producing lots and lots of seedlings from winter sowing is a fraction of buying any plant for your garden.
Trudi Davidoff is the president of WinterSown Educational: wintersown.org. Visit the site for FAQs, seed lists, pictures, and more, and check GardenWeb.com and Facebook for winter sowing groups.