Asclepias tuberosa aka Butterfly Milkweed

Asclepias tuberosa is called butterfly weed or butterfly milkweed. This perennial belongs to the dogbane family, Apocynaceae. Its native range runs from southeastern Canada to northern Mexico. It grows in prairies, fields, open woods, and roadside grassland. Wild plants often grow on dry, rocky or sandy ground. Thick roots store reserves below ground through winter. The leaves and stems die back during winter dormancy.

Garden plants form clumps about 1–2.5 feet [0.3–0.76 metres] tall. Missouri Botanical Garden gives a spread of 1.5 feet [0.46 metres]. Other sources report heights near 3.3 feet [1 metre]. Florida plants can spread 3 feet [0.91 metres] wide. Hairy green stems stand upright or lean outward. They branch near the top and bear narrow green leaves. The leaves grow singly in a loose spiral. This milkweed has clear sap rather than milky sap.

Orange or yellow-orange flowers form clusters above the leaves. Some plants have flowers with red tones. Each flower has five petals and a crown of hoods. Bloom dates vary by source, from May into early autumn. June through August is the Missouri Botanical Garden range. Long, pointed pods follow the flowers and turn brown. Ripe pods split and release seeds with silky tails. Wind carries the seeds away from the parent plant. The pods also serve in dried flower displays.

Give this plant full sun and soil that drains well. It grows in poor soil and withstands drought. Sources list sand, loam, and clay among suitable soils. Wet ground can cause crown rot. Seed-grown plants may need two or three years to flower. Their deep taproot makes moving established plants hard. New shoots emerge late in spring, so mark dormant crowns. Sources give USDA zones 3–9, with Florida extending to zone 10. The RHS rates it H4 for UK conditions. Plants can self-seed beyond their planting site.

Use butterfly weed in sunny borders, meadows, or rock gardens. Flowers feed butterflies and other insects with nectar. Monarch and other caterpillars feed on the plant. Deer tend to leave it alone. Aphids, rust, and leaf spot can occur. Stems have supplied fibre, and roots have served in herbal medicine. PFAF records food uses after cooking, but eating carries risks. Large amounts can cause vomiting, diarrhoea, and other illness. The sap can irritate skin and eyes. Wear gloves when handling it.