AMES, Iowa – When temperatures are cold outside, it’s the perfect time to plan spring plantings. Include butterfly weed, a pretty, low maintenance perennial, in those plans to add significant beauty and value to a lawn. For maximum growth and beauty, specific growing procedures should be followed.
These tips from horticulturists with Iowa State University Extension and Outreach instruct how to best handle butterfly weed.
What would be a good planting site for butterfly weed?
The butterfly weed (Asclepias tuberosa) is a member of the milkweed family. Plants grow two to three feet tall and produce flat-topped clusters of bright orange flowers from July through September. Their flowers attract several butterfly species, hence the common name.
Butterfly weed is an easy-to-grow, low maintenance, long-lived perennial. It performs best in full sun. Plants should receive at least six hours of direct sun per day. Plants grow well in a wide range of soils. However, good soil drainage is a must. Once established, the butterfly weed possesses excellent heat and drought tolerance. Because of the butterfly weed’s long taproot, transplanting is difficult. Carefully choose a planting site and don’t disturb it. Also, the butterfly weed emerges slowly in spring. To prevent possible injury, mark the planting site and don’t cultivate in the area until the plant emerges.
While most butterfly weeds produce bright orange flowers, a few plants in the ‘Gay Butterflies’ mixture have yellow or red flowers. The cultivar ‘Hello Yellow’ has yellow flowers.
Can the butterfly weed be divided?
The butterfly weed possesses a long taproot. Because of its long taproot, division is difficult and generally not recommended. The butterfly weed is most commonly propagated by seeds.
How do I germinate butterfly weed seeds?
Harvest the seed pods of butterfly weed when the pods begin to split. Seeds can be sown directly outdoors in late fall or started indoors.
When sowing seeds outdoors, work up the soil in a protected location in early to mid-November. Scatter the seeds over the prepared seed bed and then cover the seeds with approximately 1/4 inch of soil. The cold, moist conditions over winter improve seed germination. Seedlings should emerge in spring. Carefully transplant the seedlings to their permanent locations when the seedlings are three to four inches tall.
To start seeds indoors, fill a flat with a commercial germination medium. Moisten the medium. Scatter the seeds over the surface of the germination medium and lightly press the seeds into the material. Cover the seeds with an additional 1/4 inch of the germination mix. Carefully moisten the additional material. Slide the flat in a plastic bag and place the bagged flat in the refrigerator. Leave the flat in the refrigerator for four to six weeks. After four to six weeks, remove the flat from the refrigerator and place it in an area with a temperature of 70 to 75 degrees Fahrenheit.
Seeds should begin to germinate in three to four weeks. (If no seedlings appear after four weeks, place the flat back in the refrigerator for another four to six weeks and repeat the process.) Take the flat out of the plastic bag as soon as seedlings appear and place the flat under fluorescent lights in a 60 to 65 degree Fahrenheit location. Transplant the seedlings into individual pots when the seedlings are one to two inches tall. Continue to grow the seedlings indoors under fluorescent lights for several more weeks.
Prior to planting outdoors, place the seedlings outdoors in a shady, protected location and then gradually expose the seedlings to longer periods of direct sun. Plant the seedlings in their permanent locations after they have hardened outdoors for 10 to 14 days.