Ornamental · Apocynaceae
Butterfly Weed
Asclepias tuberosa
Give it full sun and poor, dry ground, then step back and let it be; the monarchs will find it on their own.
Full sun
USDA 3–9
1–3 ft · 0.3–0.9 m
Overview
Stand close and butterfly weed reads as a low, leafy mound topped by flat clusters of small orange stars, each bloom packed tight against its neighbors so the head sits nearly level. The color carries from a distance, a deep saturated orange that some named forms trade for a clear, glowing yellow.
The stems hold narrow, dark green leaves that spiral up toward the flowers, and snapping one open reveals clear sap rather than the milky white running in its milkweed kin. Below ground sits a thick, fleshy taproot, the engine that drives the whole plant and the reason it dislikes being dug up once settled.
Blooming runs from late spring through summer, after which slim seed pods form and eventually split. Each winter the top growth dies back completely to the soil, and the following spring fresh stems push up again straight from that buried taproot.
Care
The short version: plant butterfly weed in full sun and lean, dry, well-drained soil, then water it rarely and skip the fertilizer entirely. Pick its permanent home at planting time, because the deep taproot will not tolerate a move, and cut the spent stems to the ground once a year.
Light
Plant it where the sun pours down for at least six hours a day. Push it into part shade and the stems lose their upright carriage and most of their flowers fade away, so a bright, open spot brings out its best.
Water
Water young plants until they take hold, then water only rarely. This is a drought tolerant species that runs happier dry than wet, and ground that stays soggy will rot the crown. Let the soil dry out completely between drinks.
Soil
Lean beats rich here. It does well in average to poor, dry to medium, well-drained soil, and it takes clay, sand, loam, or shallow rocky ground as long as the drainage stays sharp. Aim for a pH between 6.0 and 7.0.
Temperature
A tough cold-hardy native, it weathers -40°F to 100°F (-40°C to 38°C) across USDA zones 3 to 9. The top growth dies back to the ground each winter and rises again from the taproot come spring.
Humidity
Ordinary outdoor air suits it, with no humidity figure to chase. What matters more is steady air movement, since still, damp air around the foliage invites rust and leaf spot.
Feeding
Do not feed it. The plant evolved on poor, lean soils, and extra richness backfires into floppy growth and fewer flowers. Skip the fertilizer altogether.
Pruning
This is light work. Cut the spent stems to the ground in late fall or early spring, and snip seed pods before they split if you want to hold back self-sowing. Leave established plants where they stand, because the taproot will not forgive a move.
Size & spacing
Mature plants reach 1 to 3 feet (30 to 91 cm) tall in a clump roughly 12 to 18 inches (30 to 46 cm) wide. Give each one room so air moves freely and the foliage dries quickly.
When to plant
Timing follows the cold winters of the temperate northern hemisphere, where seed wants a chilling spell before it will sprout and the plant times its bloom to the warm months.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter, about 8 to 10 weeks before last frost, after 30 days cold moist stratification
- Plant: Spring after last frost, or direct sow in fall to allow natural cold stratification
- Harvest: Late spring through summer (roughly May to August)
Hardiness
USDA hardiness zones: 3–9
Temperature: down to -40°C
Troubleshooting
Most trouble traces back to either wet soil or a disturbed root, and the few pests it draws are usually worth tolerating for the sake of the caterpillars sharing its leaves.
Stems going dark and soft at the soil line
A plant that flops over with blackened, slimy stem bases is almost always sitting in ground that stays too damp. The crown turns soft and rotted where it meets the soil. Pull back on watering and shift this plant into lean, sharply drained earth in full sun, since soggy roots are the one thing it cannot survive.
Fix:
- Improve drainage and stop supplemental watering
- Plant in lean, well-drained or rocky soil in full sun
A moved plant that sulks and withers away
Dig up a settled clump and you risk severing its long fleshy taproot, which sends the whole plant into decline. Once it has rooted in, this species refuses to be relocated. Start fresh seedlings right where you want them instead of lifting and shifting an older plant.
Fix:
- Leave established plants undisturbed
- Start new plants from seed in place rather than transplanting
Tiny orange bodies crowding the stem tips
When you see bright yellow-orange specks packed shoulder to shoulder along the soft top growth, those are oleander aphids clustering on the tenderest stems. Rinse them off with a firm jet of water every two or three days for about a week, and tolerate a few stragglers since monarch caterpillars often share the same leaves.
Fix:
- Knock aphids off with a strong spray of water every two or three days for about a week
- Tolerate minor infestations to protect monarch larvae and beneficial insects
Rusty bumps and dark flecks across the foliage
Raised orange pustules that smear into powder when rubbed, or scattered dark spots ringed with yellowing, point to a fungal problem on the leaves. These thrive where air sits still among crowded plants. Strip off the marked leaves and open up the spacing so breezes can dry the foliage between rains.
Fix:
- Remove and discard affected foliage
- Improve air circulation by spacing plants
Toxicity
Every part of this plant carries cardiac glycosides, so while its low latex makes it cleaner to handle, it stays a real hazard to animals that graze or chew it.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Mild
A nibbling cat usually shows vomiting, diarrhea, a refused food bowl, and a tired, weak look. Should it chew a large amount, watch for seizures, labored breathing, a faint or racing pulse, widened pupils, and strain on the heart.
Dogs Mild
Most dogs that taste it get an upset gut: vomiting, diarrhea, lost appetite, and a sluggish, weak demeanor. A bigger mouthful can bring on seizures, trouble breathing, a thready or pounding pulse, dilated pupils, and effects on the heart.
Horses Moderate
A horse may turn dull and weak with vomiting and loose manure after grazing it. Larger amounts can leave the animal staggering, fitting, with a weak or quick pulse, struggling to breathe, and the heart at risk of failing.
Rabbits Toxic
Stop a rabbit from nibbling the leaves, since the same cardenolides hit a small grazer quickly. Expect a roiling gut, weakness, and a heartbeat that begins to falter.
Livestock Severe
Cattle and sheep that graze it can go weak and unsteady, lose control of the hindquarters, fall into seizures, and slip toward coma within hours, with death possible from heart and breathing failure.
Birds Toxic
Keep poultry and pet birds clear of it, because the heart-acting compounds strike a small bird hard. Pecking at the leaves or seeds is a genuine danger.
People Caution
This is not food; even a small taste upsets the stomach and unsettles the heart. The sap can sting skin and eyes, so wear gloves and keep children from chewing on leaves or pods.
Keep grazing animals away from the plant, as livestock such as cattle, sheep, and horses can be seriously poisoned. Wear gloves when handling, as sap may cause skin and eye irritation.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Beyond the wild orange-flowered species, a handful of selections push the color toward yellow or tune the plant's stance, while one wild subspecies stands apart by its foliage.
Hello Yellow
A standout selection that swaps the species orange for flowers of clear, glowing yellow across each flat-topped cluster.
Blonde Bombshell
A yellow-blooming cultivar chosen for its strong upright stems and an unusually heavy load of flower heads.
subsp. interior
The wild interior form of the central United States, told apart by its leaf shape and the way each leaf meets the stem.
How to propagate
Seed is the dependable way to add more plants, since the fleshy taproot makes division a gamble that rarely repays the effort.
SeedModerate
Sow after about 30 days of cold moist stratification in late winter, or direct sow in fall for natural stratification · Typically 2 to 3 years from seed to first flowering
Seed is the standard route, but the deep taproot dislikes being moved, so drop seed straight into its permanent spot. Give it roughly 30 days of cold moist chilling, starting in late winter or sown in fall for natural cold, to lift germination, then expect 2 to 3 years before the first blooms appear.
DivisionModerate
Early spring, only on younger plants if at all · Slow; the deep taproot resents disturbance
Splitting a clump rarely pays off; the deep taproot resents being cut and recovers slowly, so limit any attempt to young plants in early spring. Root cuttings are a more reliable path because they spare you from heaving the whole established crown out of the ground.
Myths
Butterfly weed bleeds milky sap and leaves the same sticky mess as every other milkweed.
This is the one milkweed whose sap runs clear rather than white, so a cut stem stays clean on your hands. It still holds cardenolides and can sting skin and eyes, so pull on gloves regardless.
All milkweeds are dangerously toxic to the very same degree.
The amount of cardenolides shifts a lot from one milkweed to the next, and butterfly weed sits near the low end, far gentler than its cousins. Gentler is not safe, though, and it stays poisonous to pets and grazing animals.