Narrowleaf milkweed or Mexican whorled milkweed is a flowering perennial sending up many thin, erect stems and bearing distinctive long pointed leaves which are very narrow and often whorled about the stem, giving the plant its common names. It blooms in clusters of lavender or lavender-tinted white flowers which have five reflexed lobes that extend down away from the blossom. The fruits are smooth milkweed pods which split open to spill seeds along with plentiful silky hairs. This plant is common in the western United States and has the potential to become weedy.
Milkweeds in general are the larval host plants for Monarch butterflies, and this species is probably the single most important host plant for Monarch butterflies in California. Milkweed gardeners should be prepared for the plant to be eaten by Monarch caterpillars, but will be rewarded by the presence of beautiful Monarch Butterflies. The plant is deciduous in winter and will sometimes die back to the ground before reviving in the Spring, and is often covered with aphids, so often best to plant in less prominent spots in a garden.
It’s very easy to grow in soils with with good drainage, even with no summer water.
Moisture: Low, Moderate-High
Summer Irrigation: Max 2x / month once established
Ease of Care: Moderately Easy
Cold Tolerance: Tolerates cold to 5° F
Soil Drainage: Fast, Medium, Slow
Soil Description: Tolerates a variety of soils including sandy, clay and saline. Tolerates Saline Soil. Soil PH: 6.0 – 8.0
Common uses: Butterfly Gardens, Deer Resistant, Bird Gardens
Companion Plants: Works well with a wide variety of other plants, but is best used where its winter leaf loss and summer consumption by caterpillars will not be the center of attention. Also, plant a number of Milkweeds in proximity so that caterpillars will have a sufficient amount to eat. Use with showy, nectar-rich plants that will attract adult Monarchs, such as Indian Mallow (Abutilon palmeri), Ceanothus sp., Western Thistle (Cersium occidentale), California Aster (Corethrogyne filaginifolia), California Fuchsia (Epilobium canum), Buckwheat (Eriogonum sp.), Mint (Monardella sp.), Monkeyflower (Mimulus sp.), Penstemon sp., Sages (Salvia sp.), Apricot Mallow (Sphaeralcea ambigua)
Maintenance: It is crucial to not use any pesticide on this plant or in its vicinity because doing so will be fatal to Monarch caterpillars.
Sunset Zones: 3*, 7*, 8*, 9*, 10, 14*, 15*, 16, 17, 18*, 19, 20, 21, 22, 23, 24