Milkweed is the only food source for Monarch Caterpillars and are a mixture of the best nectaring plants for all butterflies. Natural Bridges State Park is just over the mountains in Santa Cruz and is a major destination of the Monarch butterflies.

Known to have some medicinal value as a cough expectorant, the plant’s milky white sap can also cause irritation if it comes into contact with your eyes. Asclepias contain cardiac glycosides that are poisonous to humans, but they pose the most danger to grazing animals.

Butterfly Milkweed, Butterfly Weed, Pleurisy Root

Asclepias tuberosa


Family: Apocynaceae (a-pos-ih-NAY-see-ee) (Info)

Genus: Asclepias (ass-KLE-pee-us) (Info)

Species: tuberosa (too-ber-OH-suh) (Info)


Category: Perennials


Height: 24-36 in. (60-90 cm)


Spacing: 15-18 in. (38-45 cm)



USDA Zone 4a: to -34.4 °C (-30 °F) to USDA Zone 10b: to 1.7 °C (35 °F)


Sun Exposure: Full Sun


Danger: Parts of plant are poisonous if ingested


Bloom Color: Orange; Bright Yellow


Bloom Time: Mid Summer; Late Summer/Early Fall


Foliage: Herbaceous


Other details:

This plant is attractive to bees, butterflies and/or birds

Drought-tolerant; suitable for xeriscaping

Self-sows freely; deadhead if you do not want volunteer seedlings next season


Soil pH requirements:

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)


Patent Information: Non-patented


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

From seed; direct sow outdoors in fall

From seed; winter sow in vented containers, coldframe or unheated greenhouse

From seed; stratify if sowing indoors


Seed Collecting:

Bag seedheads to capture ripening seed

Allow pods to dry on plant; break open to collect seeds

Properly cleaned, seed can be successfully stored


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