Even in the bitter cold months of winter, you can start planting your spring garden outside using these ideas for homemade, mini greenhouses made from recycled containers.
Winter sowing is a method of starting seeds early in tiny greenhouses made from empty milk jugs. The process is inexpensive, uses recycled materials, requires no electricity, produces healthier plants and offers an outlet for gardeners to start planting in the winter. Plus, it’s fun!
There are many plants that can be seeded in winter. Most flowers, herbs and vegetables will do well. Native plant seeds are perfect for winter sowing because many need a cool, moist stratification period to germinate. These homemade greenhouses and their seeds will endure the freezing and thawing of winter months and can even handle being covered in snow and ice.
The basic concept is to plant seeds in potting soil placed in a plastic container, add water, cover, label the container and place in a full-sun, protected area outside. The seeds will sprout when the weather is right, and when it’s warm enough in the spring, seedlings can be planted in the garden.
These plants do well in the Midwest:
- Flowers (mostly native and perennial): coneflowers, butterfly weed, blazing star, passion flower, cardinal flower, cardinal vine, standing cypress, lupine, Mexican hats, blanket flower, coreopsis, black-eyed Susan, mallow, yarrow, sweet William, hyacinth bean, purple and red flax, bee balm, cleome, golden rod, verbena, wallflower, foxglove, nasturtium, columbine, salvia, morning glory and snap dragon.
- Herbs: anise hyssop, basil, bee balm, cilantro, primrose, lavender, parsley, pineapple sage and sage.
- Vegetables: beets, broccoli, Brussels sprouts, cabbage, corn, eggplant, parsnip, peppers, spinach and tomatoes.
Make your own mini greenhouses
To get started, you’ll need several milk jugs or plastic containers, seeds, potting soil, a box cutter, knife or scissors to cut the plastic and either duct tape, clear packing tape or pipe cleaners for closing the milk jug. The containers can be recycled one-gallon plastic milk or water jugs, two-liter soda bottles, rotisserie chicken containers or even the plastic take-out cartons that have become prevalent during the COVID-19 pandemic. The plastic does not need to be totally clear, but it does need to let light penetrate.
- Using a milk jug, make a horizontal slit with a sharp knife right at the side of the lower end of the handle.
- Place the scissors or box cutter into the slit and cut around the jug and stop cutting about 1½ inches from the starting point, leaving this portion intact to make a hinge.
- Poke drainage holes in the bottom of the jug and along the very lowest portion to provide adequate openings for drainage and watering. You can water from the bottom so as not to disturb the seeds/seedlings.
- Leave the small opening at the top uncovered to allow snow, rain or ice to enter.
Plant your seeds
Start by pre-soaking three to four gallons worth of a perlite peat moss mixture in advance to be sure it is well saturated. Line the bottom of each milk jug with a couple layers of newspaper. Then place three to four inches of soil and add a little more water until it drains out the bottom. The soil should be really wet because that’s how this system works.
Then plant the seeds according to the packet directions. If you don’t have new seeds, older ones will usually germinate, but the yield will be smaller.
In nature, the seeds are just scattered, however, you can plant in neat rows. Then lightly smooth the soil over the seeds.
Close the lid and secure it with duct tape or by twisting a pipe cleaner between a hole in the top and bottom sections — for easy opening and closing. Finally, label your treasures with a fade-resistant, waterproof marker — or you could be in for some surprises come spring.
Place in a sunny, protected spot
To find a perfect home for your greenhouses, look for an outside location that is out of the wind, preferably in nearly full sun near a foundation or wall. They should face the elements, but not be in the direct path of dogs, cats or vehicles.
Enjoy your garden
Germination really depends on your seed varieties. Amazingly, plants will sprout when the time is right for them. Then you can plant the seedlings in the garden at the time recommended for each variety. So, broccoli still gets planted well before tomatoes.
Want more help? Sign up for free workshop
The Missouri Department of Conservation is offering two free Winter Sowing workshops on Saturday, January 22 at the Anita B. Gorman Conservation Discovery Center, 4750 Troost Ave., Kansas City, MO.
All participants will take home a mini greenhouse planted with native plant seeds. The workshops include a tour of the native prairie at the center.
Top photo: Deep Roots KC