Snip off the pod using pruning shears. Slice lengthwise along the edge using a utility knife. Pry open the seed pods. Scoop out the seeds and fluffy matter inside and place it in a bucket.
Arrange the starter pots on a propagation mat near a source of bright, indirect light such as near a partly shaded south-facing window. Set the temperature on the propagation mat to 86 F during the day. Turn it off at night.
Butterfly weed and milkweed seed pods may be harvested and planted to support Monarch butterfly caterpillars. Butterfly weed grows well from seeds, which must be harvested in late summer and either sown immediately in the garden, or started in spring after a lengthy chilling process. The seeds are viable and will germinate with little care, although they must be planted at the appropriate depth to ensure successful sprouting.
Make a 1/4-inch-deep planting hole in the center of compost mixture. Drop one butterfly weed seed in the planting hole. Cover it with a loose layer of compost. Mist the compost to settle it.
Place the butterfly weed seeds in a plastic bag filled with 1 cup of moistened perlite. Store the bag inside the refrigerator for three months. Mist the perlite with water every few days to keep it from drying out completely.
After the flowers fade and fall from the butterfly weed, it produces long, beanlike seed pods. These turn from green to brown as the seeds within mature. When the seeds are ready, the pod bursts open, releasing the seeds. The seeds are covered in feathery white silk to help them take to the wind. For this reason, you will need to keep an eye on the pod and grab it from the plant as it starts to pop open.
Butterfly weed develops a long tap root and doesn’t tolerate transplanting, so sow the seeds directly into the garden after stratification. Choose a planting spot that receives full sun. Because butterfly weed tolerates even poor soil, there is no need to amend the soil unless it’s heavy. In that case, add a 3-inch layer of compost and dig it into the top 6 inches of soil. Set the seeds on the surface of the soil and cover them with a 1-inch layer of sand.
Preparing the Seeds
Because butterfly weed (Asclepias tuberosa) is a host for the monarch butterfly, it is considered an important native plant. It is also an essential component of a butterfly garden. Easy to grow, butterfly weed is drought-tolerant and grows in any soil as long as it drains freely. Sowing butterfly weed seed directly into the garden in August is the best way to plant it. Butterfly weed grows in U.S. Department of Agriculture plant hardiness zones 3 through 9.
Butterfly weed seeds are dormant when released from the pod and need a chilling period before they will break dormancy. You can mimic the cold period by refrigerating the seeds. Enclose them in a sandwich bag full of moist peat moss, seal the bag and refrigerate the seeds for 12 weeks. This process is known as cold-moist stratification.
Planting the Seeds
Water the butterfly weed seed bed carefully after sowing the seed, so the top 3 inches of soil are moist. Although at maturity the plant tolerates extended periods of drought, the seeds require consistently moist soil during germination. Once they emerge, thin the seedlings to 15 to 18 inches apart and allow the soil to gradually dry out until it is dry between waterings.
These are very similar plants and members of the same plant genus. Both are of great value to butterflies and other pollinators. But butterfly weed has notable orange flowers, while milkweed has white or pink/mauve flowers. Further, milkweed is notably toxic, with the potential for fatality if large quantities are consumed by humans or animals. Butterfly weed, on the other hand, has rather mild toxicity, and fatalities are very rare.
Though butterfly weed does not need much pruning throughout the year, it can be cut back to the ground ahead of the winter season. In late autumn, you’ll notice the leaves on the butterfly weed are beginning to yellow and the stems are drying out and turning brown. This is a sign that the plant is entering dormancy for the season—at this point, you can take a clean set of pruning shears and cut the plant to the ground, where it will stay until it reemerges in spring.
Butterfly weed is, of course, a mainstay of butterfly gardens, though it is not quite as attractive to monarch butterflies as is the common milkweed. It is also commonly used in meadow gardens or any landscape design devoted to natural wildflowers. In the mixed border, landscapers find that the bright orange color blends well with blues and purples, such as purple coneflower, Liatris, or globe thistle. It also works well when blended with other yellow and orange flowers, such as coreopsis or black-eyed Susan.
In most circumstances, butterfly weed is largely trouble-free, but it can be susceptible to root rot if it is planted in dense soil that gets too much moisture. It can also be susceptible to fungal diseases such as rust and other leaf spots, though these are usually merely cosmetic and not fatal.
Common Problems With Butterfly Weed
The plant can be susceptible to aphid damage, which usually is controlled by lady beetles and other predator insects unless the infestation is severe, at which point you can spray with an insecticidal soap or pesticide.
Typically, the easiest and most successful way to add butterfly weed to your garden is to grow it from seed. Plant fresh seeds in fall for growth the following spring, or allow any established butterfly weeds already in your garden to do the work for you.
Other than the root rot that can appear in dense, wet soils, there are only a couple of common problems with butterfly weed.
Types of Butterfly Weed
If possible, choose a spot in your garden that boasts lots of bright sunlight daily, as this plant loves to soak up the rays. Full sun is definitely your best bet, but his hardy plant can tolerate a few hours of shade, too.
During its first year of life (or until new plants start showing mature growth), you should maintain a moist soil environment for butterfly weed, giving it about 1 inch of water per week through combined rainfall and irrigation. Once the plant appears to be well-established, you can cut back to watering it only occasionally, as it now prefers dry soil. Mature plants can do well with just monthly watering in all but the driest climates.