Planting Milkweed
Milkweed is a warm season flower in the Apocynaceae family. Getting the timing right is the difference between a strong stand and a disappointing one, so the windows below are given relative to your own last spring frost and first fall frost rather than a generic calendar date. Look up your local frost dates and count back or forward from there.
Milkweed is started indoors 8–10 weeks before your last spring frost date, giving seedlings a head start before they move outside.
You can sow Milkweed directly into the garden 2–4 weeks before your last frost.
Milkweed can be grown by direct sowing and starting indoors. Starting indoors gives the longest, most controlled season, while direct sowing is simplest where the season is long enough.
Spacing and Planting Depth
Give Milkweed room to mature. The figures below come from verified extension and seed-supplier data for typical varieties.
| Spacing in row | 18 inches |
|---|---|
| Row spacing | 24 inches |
| Plants per sq ft | 0.33 |
| Planting depth | 0.25 inches |
| Sun requirement | Full sun |
Days to Maturity
Milkweed reaches maturity in 120–150 days from transplant.
Milkweed is ready to harvest after about 135 days. Harvest before the first fall frost, which will end the plant's productive season.
Conditions and Care
As a warm-season flower, Milkweed needs warm soil and settled weather to thrive, and is set back or killed by frost. It is frost hardy and can shrug off light freezes, so it can stay in the ground later into the season than tender crops.
Milkweed needs full sun — give it at least six hours of direct light a day for the best growth and flavor. Sow seed about 0.25 inches deep — small seed is sown shallow and barely covered, then keep the soil evenly moist until seedlings establish.
Milkweed belongs to the Apocynaceae family; rotating where you grow members of this family each year helps limit the build-up of soil-borne pests and disease. Milkweed is generally grown as a single planting each season rather than succession sown.
Growing Notes
Perennial; needs cold stratification. Monarch host plant.