Seed Sowing in Cold Weather Conditions
In the heart of winter, gardeners can still nurture the growth of difficult perennials by employing a combination of cold stratification and winter sowing techniques. These methods, which mimic natural winter conditions, provide the perfect environment for seeds to break dormancy and germinate in spring.
### Cold Stratification for Seed Germination
Cold stratification, a process that replicates winter's cold, moist conditions, is essential for many perennials, such as the purple coneflower (Echinacea purpurea) and black-eyed Susan (Rudbeckia hirta). To cold stratify seeds, place them in a moist substrate, like damp paper towels or soil, inside a sealed plastic bag, and refrigerate them for a month or more, depending on the species.
### Winter Sowing Using Recycled Plastic Containers
The winter sowing method, an eco-friendly and affordable approach, uses recycled containers like milk jugs or water bottles as mini-greenhouses to protect seeds over winter while exposing them to natural cold and moisture cycles. To create these mini-greenhouses, wash the containers, cut them open most of the way around, leave hinges to hold the tops and bottoms together, and poke drainage holes in their bases. Fill them with seed-starting soil, sow seeds inside, secure the lid loosely, and place them outdoors in a somewhat sheltered but not fully shaded spot.
These mini-greenhouses trap some warmth without overheating, creating favorable conditions for stratifying seeds outdoors and promoting natural germination in early spring. It's essential to use ventilation holes to prevent overheating, avoid placing soil too close to the opening to prevent drying out, and open lids on warmer days after germination to avoid excess humidity and mold.
### General Seed Starting Tips
When starting seeds, use moist but not soaking seed-starting media to ensure consistent moisture without drowning seeds. Keep soil temperature appropriate to the seed type, warm for germination, then move seedlings to cooler conditions to harden off. Transplant seedlings after strong root development, and mimic the seed's natural environment as much as possible to increase germination success.
By combining these methods, gardeners can successfully bridge difficult perennials over winter for spring germination and growth. Place the "greenhouses" in a protected, sunny, south-facing location outdoors and leave the lids off the jugs or bottles to provide air and allow rain or snow to moisten the soil. It's recommended to put this type of sowing off until December if the November is warm to prevent seeds from sprouting in autumn instead of spring.
Norman Deno's book Seed Germination Theory and Practice provides details on which seed varieties require cold treatment. For those who wish to delve deeper into the world of seed stratification, Deno's book is an invaluable resource.
- Utilizing cold stratification and winter sowing techniques, one can nurture a lifestyle that involves gardening even during winter months, helping home-and-garden enthusiasts to maintain their perennial plants.
- In warmer regions, gardeners may find success in employing winter sowing methods to grow perennials from seeds, using recycled plastic containers as mini-greenhouses to mimic natural winter conditions, promoting seed germination in spring.
