Starting native plant seeds in Wisconsin
Gardening with native plants is a wonderful way to enhance biodiversity in your yard. By starting seeds in the winter, your native plants can get a jump start on spring and you can grow lots of species for very little money! Once you have your seeds (purchased or collected locally), you’ll need a few supplies and a couple months of winter weather.
In a natural setting, native plants would flower in the spring, summer or fall, then drop their seeds in fall. Those seeds sit on and in the ground for the winter, freezing and thawing as the temperatures change. Our goal is to mimic that activity using milk jugs.
Timing:
In southern Wisconsin, you can start native seeds anytime between mid-November to early-January. Since you need at least 6 weeks of consistently cold (below freezing) temperatures to activate germination, you may run out of sufficient winter weather if you start seeds after early January.
Gather your supplies:
One half-gallon or gallon milk/juice jug per species you want to grow (without the cap),
A drill and bit or scissors to punch holes in the bottom of the milk jugs,
Scissors,
Duct tape,
Ziplock sandwich bags, paper, and a permanent marker,
Potting or seed starting soil,
Native plant seeds,
A place to set the jugs outside for the winter where snow or rain will fall on them for at least 6 weeks.
Process and steps:
To start, drill or punch 4-5 holes in the bottom of each of your milk jugs. This is important for drainage.
Next, cut your milk jug in half, leaving one small section near the handle connected. Open the jug.
Fill the bottom half of the jug with potting soil, leaving about 1 inch of space below the edge.
Scatter seeds of one species in the milk jug, using your fingers to wiggle and scratch the soil to incorporate the seeds. They do not need to be deep (just a bit below the surface of the soil).
Gently water the soil if there is no snow outside (if there is snow, hold off on this step, and see Step X).
Close the milk jug, and use duct tape to tape the jug shut. Do not put the cap back on the jug.
On a small piece of paper or index card, write the name of the species of seeds you just planted. Put it inside a ziplock bag, zip it shut and fold it in half to prevent water from seeping in through the zipper and getting the paper wet.
Put the side of the paper you wrote on facing the jug (this helps prevent the sun from fading the text), and tape the baggie to the jug on top and bottom.
Put the jug in a spot that will allow sun, rain, and snow to access it.
If there’s snow on the ground, pour snow in through the open cap so the soil is covered with a few inches of snow.
The seeds are planted. Now what?
Then, you leave them alone until spring! If it’s a dry winter, you can water the milk jugs now and again. Keep an eye on them when the weather gets warm — you will need to remove the tape and open the milk jugs in late April or May to prevent the seedlings from getting overly hot, wilted, or squished together. Keep them watered so the soil is moist but not soggy. Once the plants are about 6 inches tall, transplant them to your preferred location and continue watering them consistently for one full year after planting.
Scattering your seeds directly into the soil
Native plant seeds can be scattered in an area you want them to grow in fall or winter. so the seeds have the time to naturally cold stratify throughout the winter. Scattering in spring, summer, and winter is fine too, but animals (birds, mice, etc.) may eat the seeds before they germinate, and they won’t germinate until they go through winter.
Want to go a step further?
Distribution of native plant seeds is a complimentary thank-you from the Wisconsin Monarch Collaborative and Southern Wisconsin Bird Alliance, but your voluntary donation will help support our important work and enable us to continue important restoration work. If you are interested and able to make a donation, you can do so here — put “native seeds” in the comments.
Header photo by Emily Meier.
