Winter Sowing 101: A Beginner's Guide
Winter sowing is a rewarding and low-maintenance way to start seeds outdoors in the colder months. This guide will walk you through timing, container prep, seed sowing, and ongoing care, so you’re ready to grow strong seedlings for spring.
Timing
Winter sowing can be done from late December through early spring, divided into three main groups based on your seed starting time:
Early Winter Sowing (5–6 months before the last frost): Sow seeds needing a cold period to germinate, like many perennials and cold-hardy veggies. For Zone 6, this is typically December and January. Examples include delphinium, milkweed, lupine, and clematis.
Winter Sowing (3–4 months before last frost): Sow hardy perennials and annuals. In Zone 6, this is February to early March. Great candidates are Brussels sprouts, Monarda, and pansies.
Late Winter/Early Spring Sowing (1–2 months before last frost): Ideal for tender annuals and vegetables needing warmth, such as cosmos, zinnias, tomatoes, and eggplants. For Zone 6, this is late March through April.
Containers for Winter Sowing
The right container is crucial for winter sowing. Here’s what you’ll need:
Light transparency: Containers must let in light.
Weather durability: They should withstand freezing temperatures.
Roomy for roots: The container should allow adequate root space and at least 4–6 inches of potting mix.
Drainage and ventilation: You’ll need holes for drainage at the bottom and air circulation at the top.
Container Types:
Standalone containers like milk jugs, juice bottles, or clear food tubs.
Bins with individual containers inside, such as solo cups in translucent bins or bags.
Preparation: Wash containers with soapy water, rinse well, then disinfect with a bleach solution (4 tsp bleach per quart/liter of water).
Setting Up Your Containers
Cut the Jug:
Slice across the middle of the jug, leaving a hinge or fully separating top and bottom.
Add drainage holes at the base.
Moisten Potting Mix: Use organic potting mix (not seed-starting mix, which dries out too fast). Moisten until the mix can form a ball without dripping.
Sow Your Seeds:
Sow seeds at the recommended depth from the packet.
Space seeds based on preference; either scatter or sow for easy division later.
Ideally, sow one seed type per container to avoid mixing plant needs.
Label and Seal:
Label with a UV-resistant marker, such as an oil-based pen, and place tags inside or outside.
Seal the container with tape or twist ties, leaving vent holes for airflow.
Placing Outside
Place containers in a sunny, open area exposed to winter weather—snow and rain will naturally water and insulate your seeds. Avoid placing them near buildings, which can alter temperatures or reduce sunlight.
Ongoing Care
Throughout the winter and early spring, keep an eye on moisture levels and temperature:
Condensation inside the container is good, but check the potting mix during warm spells and add water as needed.
Ventilation: On warmer days, open the containers slightly if temperatures rise inside, especially for sensitive seedlings like tomatoes.
Germination and Transplanting
Seeds generally germinate in 6–8 weeks. Once seedlings have mature leaves, thin them to keep the strongest plants. Gradually increase ventilation to harden them off, and transplant them to larger pots or directly outdoors as the weather warms.
Winter sowing offers a hands-off way to produce resilient plants for your garden. With just a few steps, you’ll have a range of hardy seedlings ready for spring planting!
