How to Grow Milkweed from Seed

Winter doesn’t necessarily seem like the best time to be starting seeds outdoors in most of North America, but for one very valuable group of plants – the milkweeds – winter is the perfect time to get planting. In case you aren’t familiar with this particular group of plants, milkweeds are in the genus Asclepias, and they are the sole monarch butterfly host plant.

Monarch populations have dropped dramatically the past few decades, and more and more home gardeners want to help by including the monarch butterfly host plant in their garden.

Monarch Butterfly Host Species

When planting milkweed in your garden, it’s important to choose a species of milkweed that’s native to your region whenever possible. Thankfully, there are several milkweed species that have a broad native range and are suitable for planting across much of North America.

Two Favorite Perennial Milkweed Species for Colorado

Swamp Milkweed (Asclepias incarnata): Don’t let the common name of this milkweed fool you. Just because “swamp” is in the name, doesn’t mean this species of milkweed requires wet conditions. In fact, swamp milkweed does grow in saturated soils, but it also grows just fine in well-drained garden soil. Plant this monarch butterfly host plant in full to part sun. It grows about four feet tall and is hardy in zones 3 to 7. You can buy seeds of swamp milkweed here.

Butterfly Weed (Asclepias tuberosa): Unlike most other milkweeds, the flowers of butterfly weed are not pink, purple, or white. Instead, this milkweed species has flowers that are bright orange. Its short stature and clump-forming habit make it the perfect fit for most gardens. Butterfly weed doesn’t like to be transplanted, so starting from seed may prove more fruitful, though it can take years for a plant to go from seed to flower. Hardy in zones 3-9 and reaching just 2 feet in height, the jazzy orange flowers of butterfly weed are nothing short of spectacular.

How to Plant Milkweed Seeds

Step 1: Act like Mother Nature. For the best results when growing milkweeds from seed, simply go outdoors anytime from late fall through mid-winter and drop milkweed seeds wherever you want them in the garden, just like Mother Nature does. Do not cover the seeds! Simply press them against the soil with your hand or the sole of your shoe. Seeds of the monarch butterfly host plant require light to germinate, so if you cover them with soil, they won’t germinate come spring.

Step 2: Walk away. Seriously. That’s it. The easiest way to grow milkweed seeds is to plant them in the fall or winter forget about them. As winter progresses, they’ll naturally be exposed to the eight to ten weeks of cold temperatures required for them to germinate when spring arrives.

Seeds available at Creek Side Gardens from Botanical Interests