Butterfly weed is a member of the milkweed family and, by some reports, the only Asclepias that does consistently well in south Florida. The plant can be grown as an annual flower or as a perennial. The plants grow to two- to four-feet-tall and flower from spring until fall. The flower colors are red and orange borne in clusters at the top of the plant. Butterflies can usually be seen flying around the plant and visiting the flowers.
Scientific name: Asclepias curassavica
Pronunciation: as-KLEE-pee-us kur-uh-SAV-ick-uh
Common name(s): butterfly weed, milkweed, silkweed, bloodflower
Plant type: herbaceous; annual
USDA hardiness zones: 4 through 10 (Figure 4)
Planting months for zone 7: June; July
Planting months for zone 8: May; June; July; August
Planting months for zone 9: March; April; May; June; July; August; September
Planting months for zone 10 and 11: February; March; April; May; June; July; August; September; October; November; December
Origin: native to Central America, North America, Mexico, and South America
Invasive potential: Caution—may be recommended by UF/IFAS faculty but should be managed to prevent its escape (reassess in 2 years)
Uses: naturalizing; cut flowers; attracts butterflies; mass planting
Availability: somewhat available, may have to go out of the region to find the plant
Height: 1 to 2 feet
Spread: 1 to 2 feet
Plant habit: round; upright
Plant density: moderate
Growth rate: fast
Leaf arrangement: alternate
Leaf type: simple
Leaf margin: entire
Leaf shape: oblong
Leaf venation: parallel
Leaf type and persistence: deciduous
Leaf blade length: 4 to 8 inches
Leaf color: green
Fall color: not applicable
Fall characteristic: not applicable
Flower color: red; yellow
Flower characteristic: summer-flowering; spring-flowering
Fruit shape: unknown
Fruit length: unknown
Fruit cover: unknown
Fruit color: unknown
Fruit characteristic: inconspicuous and not showy
Trunk and Branches
Trunk/bark/branches: not applicable
Current year stem/twig color: green
Current year stem/twig thickness: thick
Light requirement: plant grows in full sun
Soil tolerances: acidic; slightly alkaline; sand; loam; clay
Drought tolerance: high
Soil salt tolerance: poor
Plant spacing: 18 to 24 inches
Roots: not applicable
Winter interest: no special winter interest
Outstanding plant: plant has outstanding ornamental features and could be planted more
Pest resistance: very sensitive to one or more pests or diseases which can affect plant health or aesthetics
Use and Management
As plants age and become somewhat woody near the base of the plant, cut them back to stimulate new growth near the bottom. This will help them look good for many years.
The best sites have exposure to sun or partial shade and almost any soil. Butterfly weed is slow to start growth in the spring. Mark its location in hardiness zones 8 and parts of 9 before the plant disappears in the winter to prevent damage to easily injured dormant crowns. A deep root (taproot) reportedly makes transplanting difficult. Once established do not disturb butterfly weed unnecessarily. Occasional fertilization can help keep flowers coming nearly all year long.
The thin stems and widely spaced leaves of the butterfly weed give a slightly weedy appearance (hence the name), so most gardeners mix them with shorter plants where the bright red and yellow flowers can be easily seen above the ground cover. The leaves can be stripped by caterpillars and the plant often looks stick-like at certain times of the year so using ground cover also helps hide the bare stems until they can be cut back. Pair with plants with large foliage and mounding or loose spreading forms to help the butterfly weed poke through the plants. White or purple flowers are complementary colors to yellow and red, which will contrast nicely.
Pests and Diseases
Aphids may infest butterfly weed.
Leaf spot diseases are seen but not serious.
Rusts cause the formation of reddish-colored spots.
Cucumber mosaic virus causes leaf mottling, but no chemical control is available.