How To Winter Sow Poppies in 5 Steps
Poppies give an early welcome to spring in beautiful style. Their saucers of papery petals bring a sweep of color in hues from crimson to purple to champagne. Gardening expert Katherine Rowe shows how to winter sow poppies in a simple process for a successful round of cheery blooms.
Contents
Poppies, with their billowy blooms that wave on wiry stems, are beloved wildflowers. They appear delicate, but they’re also durable, with seeds that hold through winter until the time is right for germination. Poppy seeds benefit from cold stratification to germinate, where seeds spend weeks in cool temperatures. As temperatures warm, their outer seed coat and inner tissues give way to sprouting.
Since poppies benefit from a lengthy chill period, winter sowing is ideal for seed-starting. Winter sowing occurs either through direct sowing poppies in the garden or the simple method of repurposing plastic containers into mini-greenhouses. Winter sowing lets us start ahead of spring and provides a foundation for sturdy seedlings.
In the winter sowing container method, seeds hold over the winter in homemade “greenhouses” with exposure to natural elements. As seedlings sprout, they develop sturdy roots poised for vigorous growth and early blooming, with no hardening-off period at transplanting. Winter sowing poppies is a streamlined seed-starting method with high germination rates. It’s easy to do and benefits the future blooms. With a few key requirements, they’ll be welcoming spring in no time.
What is Winter Sowing?
Direct sowing is the easiest way to sow seeds in winter. Poppies germinate in the cool conditions of spring after exposure to natural freeze and thaw cycles. Sowing the seeds in their permanent location avoids potential disruption to poppies’ sensitive roots during transplanting.
Poppies are also great contenders for winter sowing in protective containers to expose seeds to natural conditions while warming the ambient air. Placed outdoors, the seeds receive all they need to germinate (light, water, oxygen, and temperature variation). They develop strong roots, and the seedlings are ready to take off at planting. This early development gives the spring flowers a headstart.
The Method
A mini-greenhouse situation promotes germination with exposure to cold temperatures and garden conditions, with protection. Seedlings emerge when temperatures warm and meet their germination requirements.
The streamlined seed-starting technique uses basic household supplies, making it resourceful, budget-friendly, and achievable. It saves indoor growing space and time spent managing seedlings in a controlled environment. Mid to late winter is the time to winter sow, ideal for cold climates.
To winter sow, the “greenhouses” are repurposed plastic containers. Transparent containers like milk jugs and plastic bottles become growing vessels with a few easy modifications.
The little greenhouses sit outside in a sunny location, exposed to the elements, including snow and rain. The seeds benefit, and seedlings harden off in the natural conditions as they sprout later in the season.
Benefits
The resourceful way of promoting germination works with natural conditions. Seed starting is accessible without a lot of supplies or intensive management.
Advantages of winter sowing:
- Budget-friendly
- No need to devote indoor space to growing
- Allows early seeding
- Works with nature
- Provides cold stratification
- Good germination rates
- No hardening off period
- No intensive oversight
- Yields hardy seedlings for quick growth after transplanting
When to Winter Sow Poppies
January and February are prime for winter sowing poppies, either directly on the ground or in protective containers. In cold climates, this extends into March. Climate and temperature affect germination, and starting in freezing conditions ensures seedlings get their cold stratification. They also won’t sprout too early and risk freezing again later.
Direct Sowing
Sow poppies outside four to six weeks before your anticipated last frost or as soon as the soil is workable. In both warm and mild climates, you can sow poppies in the fall for a springtime bloom.
In Homemade Mini-Greenhouses
As early as December and January, you can winter sow poppies. Aim to sow seeds about six to eight weeks before you transplant them to the garden bed or outdoor container. In warm zones, the seeds germinate faster.
Choose the Containers
”Greenhouse” options (aka repurposed plastic containers) abound. Start with clear or transparent containers like milk jugs, two-liter bottles, bins, or freezer bags. The selection needs to allow plenty of light infiltration and have the capacity for drainage, ventilation, several inches of soil, and room for seedling growth. Clean the containers in warm, soapy water to sanitize them.
The containers need simple modifications to account for temperature variation and airflow. We’ll cover a few basic containers (milk jugs, bottles, and freezer bags) that allow for opening and closing for airflow and temperature regulation.
Stored outside, the vessels collect seasonal moisture from snow and rainfall. Drainage holes are essential in preventing rot and other fungal problems. Make four to six holes in the base of the container with a screwdriver or drill. Label and date and the variety on each with a permanent marker.
Additional translucent containers for winter sowing:
- Salad greens packaging
- Deli cake/cookie container or clamshell
- Large takeout containers
- Clear bins
Milk Jugs
To adapt a milk jug, remove the cap and poke the drainage holes in the bottom. Cut the jug nearly in half just below the handle, almost all the way around (about three-quarters). Leave the handle portion attached as a means to lift the lid during the season. The open cap allows airflow and moisture in the container, while the cut makes a hinge at the handle to open it on warm days.
Add three to four inches of potting mix to the base. Sow seeds according to the depth and spacing of the packet guidelines, covering them only lightly (they need light to germinate). Water them in, and tape the jug’s cut seam.
Plastic Bottles
Two-liter water or soda bottles make protective little greenhouses. Prep them as you would a milk jug by removing the caps and making a cut three-quarters of the way around. Leave four inches of space at the bottom of the bottle for soil and seedling growth.
With drainage holes in place, add three to four inches of soil. Sow the seeds according to packet directions and moisten the media. Tape the cut seam and place the bottle outside, cap off.
Freezer Bags
Gallon-sized resealable freezer bags become seedling pouches by clipping the bottom corners and cutting slits or holes for drainage. Add several inches of soil and sow accordingly. Water the seeds for even moisture.
Leave an inch or so of the seal open at the top of the bag for ventilation. To adjust airflow and regulate temperature on warm days, open the seam more. In spring, roll the seal down like a cuff for full exposure, closing it if necessary on chilly nights.
To stabilize the bags, string them along a skewer by piercing the tops. The bottom should rest on a tray, crate, or bin.
Bins
Clear plastic bins either hold the other vessels for support or become seedling trays themselves. Add a few inches of soil to the base, or use little paper towel tubes cut into sections to house the individual seedlings. Make holes in the lid for ventilation and moisture, popping it off to vent on warm days.
Seeding
Use a regular, high-quality potting mix for seeding. No special seed mixes are necessary. Avoid regular garden soil or straight compost, both of which are too heavy for young roots and stems. No need for formulas with moisture control or added fertilizers.
Because poppies have sensitive roots, you may experiment with scattering seeds on the soil surface or sowing them in cardboard tubes. Cut paper towel tubes or toilet paper tubes to fit and nestle them into the soil. Sow a few seeds per tube. When ready to transplant, pop the roots out of the tube, cut the tube to peel it away, or plant it with the poppy to decompose.
Sow the seeds according to varietal guidelines and spacing recommendations. Poppy seeds are tiny, and overseeding slightly is fine. Thin any extra seedlings by clipping them after they sprout.
Scatter and water in the seeds. Poppies need light exposure to germinate and emerge when temperatures are near 50-65°F (10-18°C).
Place Outdoors
Once prepped and seeded, the containers can move to a sunny spot outside with access to natural moisture. Expose them to the elements, even snow. The seeds benefit, and seedlings harden off as they sprout later in the season. A southeast exposure is ideal for sunlight and warmth. If this becomes too sunny and warm toward spring or in warmer climates, move them to an east-facing spot with good morning sun.
In windy areas, secure the vessels to keep them from blowing over. Nestle them against a foundation or wall, or place them in a milk crate, tray, or tub. Breezes help develop strong stems, but toppling over can disrupt the situation. Ensure the area is well-draining so the containers aren’t sitting in pooling water or puddles.
Maintain
Often, and especially to start, precipitation from snow, rain, and condensation is enough to maintain soil moisture. Check containers once a week or so, especially as conditions become drier or warmer as the season progresses. With regular rain or snow, the vessels need only supplemental water or misting every few weeks.
Watering needs may increase as temperatures warm and seedlings sprout. If the soil surface shows signs of drying, mist or sprinkle with water to prevent seeds or shallow roots from drying out.
Condensation is a sign that moisture is available. If it lessens, make sure soil moisture is adequate and that rain can enter the top. If not, add more openings. Keep tape in place at cut seams to prevent evaporation early in the process.
Vent the lid on warm days to allow transpiration and airflow to stave off diseases and to keep seedlings from getting too warm. Close the lid again before temperatures drop late in the day. As seedlings develop, this allows natural hardening-off that makes for easy transplanting without shock.
Transplant
Seedlings are ready to transplant after exposure to warm days in their open containers. Look for true leaves (fully developed leaves after the cotyledons) and a few inches of height as indicators of readiness.
With winter sowing poppies, we need to take care during transplanting to avoid root disturbance. Capture as much soil and roots as possible for each seedling to minimize disturbance. With winter sowing poppies, the advantage is they’re ready to transplant to develop their taproots in the soil (rather than sitting in cells or small pots and spending time hardening off).
Follow regular transplant guidelines for the best air and soil temperatures. To transplant, gently divide the seedlings. Reach into the open container or cut side flaps for access to slide them out. With the proper spacing, you can plant the entire block without dividing, but most likely, you’ll need to split up the poppies.
