Latin Name: Asclepias cryptoceras
Common Name(s): Jewel Milkweed
Family: Apocynaceae
Size: Up to a foot tall. If you want a tiny milkweed, this species is for you.
Life Cycle: Perennial
Distribution: The Great Basin, often on dry hillsides and slopes on clay, eroded basalt, or shale.
Light Requirements: Full sun
USDA Zone: 6 to 10, possibly colder.
Drought Tolerance: High once established.
Fire Risk: Presumably low while it is growing, given the fleshy leaves and short stature. If growing near a structure in a fire-prone area it is probably best to cut it down after it dies back and dries to avoid the seed fluff and dried plant matter fueling any fires.
Cultivation Notes
Once established, most milkweeds tend to be tough and adapt well to the garden. This is a good species for rocky borders in xeriscapes and can deal with neglect and full sun. If you can get the plants established from seed in their permanent location, you can avoid the dangerous process of transplanting milkweeds.
Jewel milkweed prefers full sun and can adapt to a variety of soil conditions, but generally does not appreciate wet soil for long periods of time and wants excellent drainage, especially in wetter gardens on the west side of the Cascades. Do not disturb the roots if you can help it. Once established the plants should do fine without summer irrigation, but make sure they receive regular water when young. Fertilization not needed and the plants do fine even in poor and gravelly soil. Slug control may be needed when the plants are young, as heavy feeding by non-native slugs can kill young plants. Simply remove slugs in the evening and kill in soapy water.
Ecology
The interesting flowers bloom from April through July and are very attractive to pollinators. Many specialist insects feed on this plant, and this is a host plant of the monarch butterfly. The seeds are consumed by birds in the winter, when few food sources are available.
Uses
Milkweeds are all toxic to some degree, containing cardenolides. This species is not known to be edible. It is a great source of fiber for making ropes and nets, however, and it can probably be used as a source of natural latex like their relatives.
Propagation
Seed or by division (more difficult). Seeds are easily collected and can be sown directly in the fall or in spring. Sow just under the soil surface. Germination can be slow and often is irregular. If planting in the late spring, cold stratification will likely be needed for up to two months before germination will take place. I have found milkweeds in general to be finicky when first establishing them. Young seedlings need irrigation, at least for the first year or two. The seedlings are temperamental, so it is best to transplant carefully without disturbing the roots too much. Division is difficult as well, as milkweed resents disturbance, and division is best done in winter when the plant is dormant.