I love starting plants from seed indoors. But I readily admit that nurturing them for months on end with heat mats and grow lights and watering and pinching and hardening off can become quite tedious by the time they can finally be transplanted outdoors. Winter seed sowing to the rescue!
This method of seed starting is super easy, super cost-effective and super rewarding. It also gives me something to do during the winter months when gardening season seems so far away.
how does it work?
Winter seed sowing outdoors exposes seeds to the elements, freezing, thawing, freezing, thawing, receiving rain and snow. The same conditions the seeds would experience if left to their own devices after falling from the mother plant. Seeds are potted up and set outside in January where they will spend the next few months. When the seed determines that conditions are right, it will germinate and seedlings will emerge and grow in their little pots until they are large enough to be divided and planted out into the garden.
Two huge advantages to this method are:
seeds live outside, freeing up space in my basement seed starting room for tender annuals, perennials and herbs
seedlings get their start out in the elements and are completely acclimated to the weather, alleviating the need to ‘harden off’ come spring planting time
supplies to get started
plastic, frost-free containers with good drainage. For many gardeners, milk jugs are ideal. Since I am typically sharing my seedlings with clients and plant sales, I like to use reusable 3” x 3” pots. I recommend investing in sturdy pots that are at least 3” deep to encourage deep rooting, like these from Johnny’s.
fresh seed starting soil like Johnny’s 512 Mix, Coast of Maine Sprout Island Blend, or Espoma Organic Seed Starter. It’s important to use fresh soil and avoid using soil from your garden which may contain weed seeds or other contaminants. Fill pots up to about 1/2” from top, leaving space for a thin layer of sand or grit, if indicated.
quality seeds from suppliers like Rare Seeds, Select Seeds or Maine’s Wild Seed Project. I also source from Nan Hayefield who grows and collects an incredible variety of her own seed in Pennsylvania. Sow your seeds very heavily, as close as 1'/8” apart. You will be thinning and separating them at time of transplant.
rough sand (not playground sand) or grit to lightly cover seeds to prevent them from splashing out of the pot during periods of heavy rain. The general rule of thumb is to not cover more than the depth of the seed itself. Many seeds need light to germinate, so it’s super important to use a very light touch when covering seeds. Some seeds, like Angelica Gigas need complete exposure to sun, so they don’t receive any covering at all. I like to purchase poultry grit from Nashua Farmers’ Exchange, as it’s also great to amend soil and improve drainage for container plantings.
labels that can withstand the elements. Pencil on metal or plastic can often work. After multiple attempts and failures with markers, I have recently had great success with printed labels using a Brother p-touch label machine. While this is a bit more of an investment, I think it’s worth it.
plastic plant markers like these work really well with the Brother stick-on labels (note, I have not tried using these with the marker included in the package and suspect the marker ink will not survive winter elements as well as the stick-on labels). Note: do not use wooden markers as they will degrade over winter.
container or crate with drainage to hold pots through the winter
hardware cloth or screening material to keep out the critters. I set the crates of pots directly on top of the hardware cloth and also cover the top of the frame. This will let in moisture and light, but keep out meddling chippies.
optional wood frame for additional protection from curious birds and animals. My good friend Carol made me this fabulous wood frame!
Once your seeds are tucked safely outdoors, in a semi-shaded area, they are virtually maintenance free. Water them in one time gently, then let nature take over. Watch for germination in late March or April when you will need to monitor moisture to make sure new seedlings don’t dry out. Otherwise, this will be their home until it’s time to transplant into the garden in May.
Once your seedlings have their second set of ‘true leaves’, they can be carefully transplanted into the garden, or potted up and grown on for planting at a later date. It’s also OK to keep perennials growing in their pots until fall.
try these seeds for winter sowing
Not every plant is suitable for winter sowing, so be sure to research before choosing this method. Some seeds that benefit from cold stratification and outdoor sowing include: poppies, verbena bonariensis, asters, goldenrod, monarda, New York ironweed, milkweed, penstemon, lobelia, Joe Pye weed, rudbeckia, little bluestem grasses and more!