Asclepias syriaca L.
Common Milkweed, Butterfly Flower, Silkweed, Silky Swallow-wort, Virginia Silkweed
Asclepias syriaca f. syriaca, Asclepias syriaca var. syriaca, Asclepias apocinum, Asclepias capitellata, Asclepias cornuti, Asclepias fragrans, Asclepias globosa, Asclepias grandifolia, Asclepias illinoensis, Asclepias intermedia, Asclepias kansana, Asclepias pubescens, Asclepias pubigera, Asclepias serica
Bloom Time: Summer and fall
Asclepias syriaca is a perennial clonal herb that grows up to 8.5 feet (2.6 m) tall. The simple leaves are opposite or sometimes whorled, broad ovate-lanceolate, up to 10 inches (25 cm) long and up to 5 inches (12.5 cm) wide, usually with entire, undulate margins and reddish main veins. The highly fragrant nectariferous flowers vary from white (rarely) to pinkish and purplish and appear in clusters. Individual flowers are up to 0.4 inches (1 cm) in diameter.
USDA hardiness zone 3a to 9b: from −40 °F (−40 °C) to 30 °F (−1.1 °C).
How to Grow and Care
You can easily grow Milkweeds to attract the Monarch and other flying creatures to your garden. Plant seeds of the Milkweed Plant indoors or direct sow outside after the danger of frost has passed and the soil has warmed. If the plant's appearance is too weedy for your taste, grow Milkweeds in a hidden but sunny corner or at the back of a border.
Milkweed often does not begin growing in northern gardens in time to be fully beneficial to butterflies. There you can start seeds of Milkweed inside so they will be ready to plant when the soil has warmed.
Milkweed plants benefit from vernalization, a process of cold treatment, before sprouting. They get this when planted outside but treat the seeds through stratification to speed up the growing process. Place seeds into a container of moist soil, cover with a plastic bag and refrigerate for at least three weeks. If desired, plant into containers and place under a grow light inside about six weeks before soil temperatures outside have warmed. Keep the soil moist by misting, but seeds can rot if allowed to sit in soggy soil. See more at How to Grow and Care for Milkweed Plants.
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