When seedlings do emerge, remove the plastic bag and place the flat under a fluorescent lamp in an area where the temperature remains a steady 60° to 65° degrees Fahrenheit.
This non-native plant from North America makes the best host plant for monarch eggs.
In fact, it spreads best by reseeding… replanting is not a very effective method of propagation for these plants.
Butterfly Weed Care
If a month passes and seedlings have not shown their heads, try putting the flat back into your refrigerator for another month or so. Then take it out and try again.
Although this hardy native plant grows well in a wide variety of soils, the soil you provide needs good drainage.
Because so many gardeners now recognize how beneficial butterfly weed is to the garden, seeds are very readily available online and in local garden stores.
This beautiful, blazing native plant relative of milkweed family, attracts butterflies, especially Monarch butterflies.
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.
Gather the butterfly weed seeds in late summer or autumn, once the pods dry to a light, rosy-beige color, but before they split open. Put on rubber gloves before handling the pods to protect your hands from the mildly toxic sap.
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.
Watch for germination in two to three weeks. Turn off the propagation mat one week after the seeds sprout. Move the pots into a cold frame outdoors or against a south-facing wall with noonday shade.
Leave the bucket outdoors for two or three days to let the fluff blow away. Stir the seeds occasionally to loosen more fluff. Do not worry if some of the fluff remains, since it won’t inhibit the germination process.
Sometimes called pleurisy root, butterfly weed (Asclepias tuberosa) is a perennial wildflower grown for its showy, reddish-orange flower clusters and textured, lanceolate leaves. A member of the milkweed family, it thrives throughout U.S. Department of Agriculture plant hardiness zones 3 to 9, where it is frequently added to butterfly gardens and native plant landscaping.
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 3 to 4 inches tall.
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.
To start seeds indoors, fill a flat with a commercial germination medium (such as Jiffy Mix). 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 4 to 6 weeks. After 4 to 6 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 3 to 4 weeks. (If no seedlings appear after 4 weeks, place the flat back in the refrigerator for another 4 to 6 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 1 to 2 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.