Narrow-leaf Milkweed
Asclepias fascicularis
Care
full sun
low
well-drained; tolerates clay and poor soils
1–3ft tall , 1–2ft wide
Jun-Sep · white, pink
Deciduous
Resistant
Friendly
Throughout California below 7000 ft in open dry areas
Rounded clusters of small white to pinkish flowers
Critical monarch butterfly conservation plant; milky sap; dies back in winter
Care Guide
Planting
Plant your Narrowleaf Milkweed in full sun in a spot with well-drained soil - it tolerates clay, sandy, and even saline soils, so you have flexibility here. The Bay Area's cool season (fall through early spring) is ideal for planting. Space it to accommodate its mature height of 3 feet, and don't worry about soil preparation; this plant is adaptable and forgiving.
After Planting
Water weekly for the first summer to establish, then cut back dramatically - once established, this plant needs water only twice a month or less during summer. Expect it to die back to the ground in winter as a dormant deciduous plant, which is completely normal; wait until late winter or early spring to cut down the dry stems, as Orioles may use them for nesting. The biggest mistake people make is using any pesticide on or near this plant, which will kill Monarch caterpillars - skip the bug spray entirely and let this plant do its job as California's most important Monarch host plant.
Visit Calscape for more information about Narrow-leaf Milkweed
Endangered & Threatened Species Supported
California Species of Special Concern; monarch populations declining
Wildlife Supported
Insects
Critical larval host plant throughout CA growing season Jun-Sep; spring/fall migration staging resource
Host plant for this CA endemic subspecies
Year-round larval host in southern CA; shares milkweed dependency with monarchs
Herbivorous pest; can affect milkweed vigor but rarely causes major damage
Birds
Visits milkweed blooms Jun-Sep; year-round CA resident