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 homemade, mini 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 home-made greenhouses and their seeds will endure the freezing and thawing of winter months and can even handle being covered in snow and ice.
Gardeners Ann Maxwell and Kim Tappan, both of Ottawa, KS, have been winter sowing for years and first introduced Greenability readers to the concept in 2014. Maxwell gardens on a residential city lot and Tappan grows a larger garden on her 10-acre farm just north of the city.
The basic concept is to plant seeds in potting soil placed in a mini greenhouse 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.
As local experts, Tappan and Maxwell offer these recommendations for plants that have done well in Kansas and Missouri.
- 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.
Maxwell and Tappan like planting vegetables that have a longer germination time such as tomatoes, broccoli or cabbage. But if you plant seed that germinates quicker, like lettuce or beans, the plants will still keep well in the jugs for quite a while, even if they are crowded.
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, whipped topping tubs, 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 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. In the bottom of each milk jug, 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, so that’s what Maxwell and Tappan do to mimic Mother Nature. 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.
Situate in a sunny 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.
“One day after a big snowfall, Kim had a neighbor coming to plow her drive,” said Maxwell. “Over the noise of his loader, Kim was out there yelling at him ‘don’t touch my jugs.’ Of course, she had to explain the growing process to him and show him the plant jugs that were covered completely with snow. He avoided them, but she’s pretty sure he had no idea what she was talking about.”
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.
“We both have enjoyed introducing kids to gardening and teaching them about winter sowing,” said Maxwell. “We have been saving quite a few seeds, and it will be fun to share and exchange seeds with other like-minded gardeners. But mostly, we just like the process of getting our fingers in the dirt during the winter.”
Top photo: Native butterfly milkweed can easily be started in recycled milk jugs now for planting in the garden this spring.
Second photo: Kim Tappan (left) and Ann Maxwell use winter sowing to start their gardens each year.