Red butterfly milkweed (Asclepias curassavica) is a showstopping tropical perennial that brings weeks of fiery color and nonstop pollinator activity to the garden. Native to Central and South America, this species goes by several names, including tropical milkweed, scarlet milkweed, and bloodflower. It’s hardy in USDA zones 9 to 11, where it behaves as a true perennial, and it’s grown as an annual in cooler climates. If you’re looking for a plant that earns its keep from midsummer all the way to frost, this is it.

The flowers are vivid and bicolored, with bright red-orange petals and a contrasting yellow-orange crown, and they bloom in clusters from late spring through fall. Few plants can rival that kind of long-season color, and the butterflies know it. Monarchs, swallowtails, fritillaries, and queens flock to the blooms, and monarchs use the foliage as a host plant for their larvae. If you’ve ever wanted to watch a monarch caterpillar grow up in your own backyard, red butterfly milkweed gives you that chance.

The plant reaches 2 to 3 feet tall and wide, with slender, lance-shaped leaves that are bright green and attractive even when it isn’t blooming. It’s a fast grower and will often start flowering in its first season from transplant. It prefers full sun and well-drained soil, and it’s notably drought tolerant once established, making it a great choice for water-wise gardens, containers, or hot, dry spots where other plants struggle. It’s not particular about soil fertility and actually does well in lean, sandy, or rocky ground. Red butterfly milkweed is deer resistant, which is a welcome bonus in areas where deer pressure is high. All parts of the plant are toxic if ingested, so it’s worth keeping that in mind around small children and pets.

In the landscape, red butterfly milkweed works beautifully as a border plant, in pollinator or wildlife gardens, in cottage-style beds, or in containers on patios and decks. It pairs well with other sun-loving perennials and annuals, and its vertical form adds nice structure to mixed plantings.

Plant care

Red butterfly milkweed is one of the easier plants to care for once it’s settled in. It’s not demanding, but a few simple practices will keep it looking its best and producing blooms all season long.

Watering: Water regularly during the first few weeks after planting to help the roots establish. After that, it’s quite drought tolerant and only needs supplemental watering during extended dry spells. Overwatering or consistently wet soil can lead to root rot, so it’s better to err on the dry side.

Fertilizing: In average garden soil, fertilizing isn’t necessary. If you’re growing it in containers or very poor soil, a light application of a balanced, slow-release fertilizer in spring can give it a boost. Avoid heavy feeding, which can push leafy growth at the expense of flowers.

Pruning and deadheading: Deadheading spent flower clusters encourages the plant to keep blooming. You can also cut the plant back by about one-third if it gets leggy mid-season; it’ll bounce back quickly with fresh growth and new flowers.

Overwintering: In zones 9 to 11, cut the plant back to about 6 inches in late fall or early winter and it’ll regrow in spring. In colder zones, you can try to overwinter it indoors in a bright, sunny spot, or simply treat it as an annual and replant each spring.

Monarchs and a note on responsible growing

Red butterfly milkweed is one of the most popular monarch host plants, but there’s an important consideration for gardeners in zones where it doesn’t die back in winter. Because tropical milkweed stays green year-round in mild climates, it can disrupt monarch migration patterns by encouraging butterflies to linger rather than continuing south. It can also harbor a protozoan parasite called Ophryocystis elektroscirrha (OE) when the foliage doesn’t die back naturally.

If you’re in a mild-winter region, you can still grow red butterfly milkweed responsibly by cutting it back hard in fall and winter to simulate a natural die-back. This removes old foliage that may carry OE and encourages monarchs to move along their migratory route. Native milkweed species are always a great complement to tropical milkweed in any garden.

Growing from seed

Red butterfly milkweed is easy to grow from seed. Start seeds indoors 6 to 8 weeks before your last frost date. Cold stratification isn’t required, but soaking seeds in warm water for 24 hours before planting can improve germination rates. Sow seeds on the surface of moist seed-starting mix and lightly cover them, then keep them warm (around 70 to 75 degrees F) and consistently moist. Germination typically takes 7 to 14 days. Transplant seedlings outdoors after all danger of frost has passed.

Container growing

Red butterfly milkweed thrives in containers, which makes it a great option for gardeners with limited space or those in cooler climates who want to overwinter it indoors. Use a well-draining potting mix, choose a container with good drainage holes, and place it in the sunniest spot you have. Container plants dry out faster than in-ground plants, so check soil moisture more frequently during hot weather. A pot of red butterfly milkweed on a sunny patio is practically guaranteed to draw butterflies within days of blooming.

FAQ

Is red butterfly milkweed a perennial or an annual? It depends on your climate. In USDA zones 9 to 11, it’s a perennial that comes back year after year. In colder zones, it’s grown as an annual, though you can try overwintering it indoors.

Will deer eat red butterfly milkweed? It’s considered deer resistant, largely because the milky sap in its stems and leaves is bitter and mildly toxic. That said, no plant is completely deer-proof, and hungry deer in winter may still sample it.

Is it safe to plant near children or pets? All parts of the plant are toxic if ingested, so it’s best to plant it where young children and pets won’t be tempted to chew on it. Contact with the sap can also cause skin irritation in some people, so wearing gloves when handling it is a good idea.

Why aren’t monarchs visiting my plant? Monarchs may not be present in your area yet, or your plant may still be too young to have attracted attention. Monarchs tend to find milkweed reliably once it’s blooming. Planting in a location that’s visible and not too hemmed in by dense plantings can help. Grouping several plants together also tends to make them easier for butterflies to spot.

Can I grow red butterfly milkweed indoors? It’s not typically grown as a houseplant since it needs full sun, but you can overwinter it indoors in a very bright window or under grow lights and move it back outside in spring.

When should I cut it back? In mild climates, cut it back in fall or winter to help with monarch conservation and to keep the plant tidy. In zones where it’s grown as an annual, you can cut it back mid-season if it gets leggy, and it’ll rebloom quickly.

Does it spread aggressively? Red butterfly milkweed can self-seed, and in some regions it’s considered invasive. Deadheading before the seed pods mature can help prevent unwanted spread. Check with your local extension office if you’re unsure about its invasive status in your area.