Milkweed is a drought-tolerant and deer-resistant perennial plant named for its milky latex sap. It is a great host plant for many beneficial insects including Monarch butterflies, bees, beetles, and lady beetles (ladybugs).
Of the 2000 varieties in the milkweed genus Asclepias, just 15 species are native to California. The California native milkweed species that are most commonly available commercially and grow well in this area are narrow-leaved milkweed (A. fasicularis) and showy milkweed (A. speciosa).
Milkweed plants develop large fleshy seed pods which pop open when mature, freeing the seeds. Attached to the seeds are fine tufts of hair (called pappus or silk) which aid dispersal of the seeds: as the wind blows, it catches the silky hairs, carrying the seeds away from the plant. The seeds can be collected from the pods for later propagation or left alone to re-seed themselves. Milkweed can also be propagated from cuttings or root divisions.
Milkweed is the only plant on which the Monarch butterfly will lay eggs. If larvae hatch on your milkweed you might notice the plant’s leaves being devoured by the caterpillar. Do not cut it back or pull it up. Once the caterpillar morphs into a butterfly the leaves will grow back.
Home gardeners can aid the Monarch population by adding milkweed to their landscape, pollinator garden, herb garden, or even a patio container. If you own a larger plot of land you might consider letting some of it remain wild, so that the wild nectar producing flowers are available not only for butterflies, but for other pollinators as well.
Milkweed commonly attracts a yellow aphid known as Oleander aphid. This aphid will not destroy the plant and will not infest nearby roses or vegetable gardens. It is plant specific: think of the Oleander aphid as food for the lady beetles. Avoid using pesticides or herbicides that might damage these breeding and feeding areas.
Despite having the word ‘weed’ in its name, milkweed can be an interesting addition to your home landscape. It is generally non-invasive and easy to grow and care for. Milkweed requires full sun. It will need some water until it is established. Some varieties will die back with a heavy frost or snow but will return in late spring. If the plant re-seeds itself, you can either leave the new plants in place or dig them up to share with neighbors.
Milkweed is bitter flavored and unpalatable. It is recommended that you do not plant it near livestock as it can be toxic.