How To Grow Butterfly Weed From Seed

How To Grow Butterfly Weed From Seed Several species of milkweed, or asclepias, are native to North America, and this year the Perennial Plant Association has chosen one of them as Perennial Learn how to grow and care for butterfly weed and milkweed in this article. Includes tips on planting, growing and types of butterfly weed in New England Butterfly weed is appropriately named, as the nectar- and pollen-rich flowers attract hummingbirds and hordes of butterflies, bees and other beneficial insects throughout the blooming season. Want to know more? Click here.

How To Grow Butterfly Weed From Seed

Several species of milkweed, or asclepias, are native to North America, and this year the Perennial Plant Association has chosen one of them as Perennial Plant of the Year: Asclepias tuberosa. This species, commonly known as butterfly weed or butterfly milkweed, has vivid orange flowers with nectar and pollen that are attractive to many species of butterflies and bees. The foliage of butterfly weed is not a preferred food but can support monarch caterpillars. This drought-tolerant plant grows best in a dry and sunny location, and is hardy in Zones 3 to 9.

Butterfly weed has upright stems with clusters of bright orange flowers that contrast nicely with the shiny green leaves. The stem sap is not milky, unlike others in the genus. This species of milkweed does not spread by runners like common milkweed (Asclepias syriaca) does, so it is not invasive. Butterfly weed is not attractive to deer; however, aphids can be a problem in garden settings and in the greenhouse.

Figure 2. Flower buds aborting shortly after plant was moved to a nine-hour photoperiod.

Demand for this plant is likely to be high in this and coming years. Butterfly weed will flower readily the first year after seed sowing, but there are a couple of key points for success in producing it commercially.

This species has some of the most dramatic responses to photoperiod we’ve seen. It is an obligate long-day plant, meaning that it requires long days for flowering. Plants grow rapidly under photoperiods of 14 hours or longer, and will begin flowering about eight to nine weeks after transplant when grown at an average of 68° F. However, if exposed to photoperiods of 12 hours or shorter, plants go dormant within a few days (Figure 1, pictured above). Leaves become droopy, shoot growth apparently ceases, and existing flower buds may abort (Figure 2). Unfortunately, simply moving the plants back to long days will not restore them to active growth. To break this dormancy, a cold treatment of nine weeks or longer is needed; in our trials, all dormant plants exposed to 41° F for 15 weeks subsequently flowered.

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To keep plants actively growing, it is absolutely essential to provide long days to these plants. We recommend providing a day length of at least 16 hours, or four hours of night interruption lighting. Photoperiodic lighting should deliver a minimum intensity of 2 μmol·m–2·s–1. Use lamps that provide both red and far-red radiation, like incandescent lights or LED bulbs designed to control flowering. Keep plants under these long photoperiods until natural daylengths are at least 14 hours long.

Butterfly weed develops a large tap root, which can make transplanting or division of established plants difficult. In container production, it’s very important to use a well-drained medium, so consider adding extra perlite to a typical peat+perlite mix. Be careful not to over-water during production or during cold treatments. The taproot is attractive to fungus gnat larvae, so be vigilant and check the roots if plants lack vigor.

In outdoor settings, butterfly weed can reach 3 feet in height, but in container production, our plants were 12 to 18 inches tall at first flowering. Several plant growth retardants are reportedly effective for height control including sprays of daminozide (e.g., B-Nine, Dazide) paclobutrazol (e.g., Piccolo, Bonzi) and uniconazole (e.g., Sumagic, Concise). Using several plugs per pot, or pinching seedlings soon after transplant, can help to fill out containers.

Catherine Whitman and Erik Runkle

Erik Runkle is professor and floriculture Extension specialist and Catherine Whitman is research technician in the department of horticulture at Michigan State University. Erik can be reached at [email protected] . We thank former MSU graduate students and faculty who contributed to generating this information.

How to Grow: Butterfly Weed

Late summer to fall in colors of orange, red, yellow and pink.

Mature Height x Spread

2 to 4 feet x 2 to 4 feet

Added Benefits

Native, attracts hummingbirds, attracts beneficials, drought tolerant, deer resistant

This native has less stature, compared with the butterfly bush, but is just as effective at drawing in winged friends, such a butterflies, ladybugs and beneficial insects, into the garden. It’s particularly a favorite of the Monarch butterfly. Butterfly weed is also hardier and more adapted to a wider range of soils, making it a good choice if you’re having a hard time growing butterfly bush successfully. The plant is slow to emerge in spring, so don’t give up hope. My butterfly weed often will just start growing when other plants are fully leafed out around it. But it makes up for lost time quickly growing to 4 feet tall and wide with brightly colored flowers. Once growing it has few problems.

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Where, When and How to Plant

Butterfly weed is hardy through New England. Sow seeds indoors in peat pots 6 to 8 weeks before your last frost date, thinning to one plant per pot. Or plant locally purchased plants in spring after danger of frost has passed or summer, in full sun on compost-amended, well-drained soil. Poor soil drainage is the one thing butterfly weed won’t stand. Space plants 2 to 3 feet apart. Butterfly weed has a taproot, so once planted it’s difficult to move.

Growing Tips

Keep the plants well watered the first year and fertilize once in spring with compost. Butterfly weed is slow growing at first in our cool soils, so mark where you planted it so you accidentally don’t dig it up when planting annuals and other perennials in spring.

Regional Advice and Care

Deadhead spent flowers to encourage more flowering and reduce self-sowing. Weed out self-sown seedling each spring. Be carefully when pruning the plant as the stems have a milky sap that might be irritating to your skin. Cutback the plant to the ground in fall after a frost and compost it. It needs little care once established in the garden and can be drought tolerant. Aphids can sometimes be a problem and are easily controlled with sprays of insecticidal soap. Butterfly weed plants can withstand damage from the Monarch butterfly caterpillars. Don’t spray to kill them or you’ll not have any beautiful butterflies.

Companion Planting and Design

Plant butterfly weed in a perennial garden close to where you can view the butterflies from a window or deck. Since butterfly weed can have loud, hot flower colors, pair it in the garden with complimentary colored perennials, such as Russian sage, coneflowers and ornamental grasses. It can also be grown in the cut flower garden for arrangements.

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Orange is the native flower color of the hardy, species version and it’s often sold just as Ascelpias tuberosa. “Hollow Yellow” is a yellow flowered version. “Cinderella” has pinkish-red colored flowers. “Gay Butterflies Mix” has plants in colors of red, orange and yellow.

Growing Butterfly Weed Plants: Tips On Butterfly Weed Care

What is a butterfly weed? Butterfly weed plants (Asclepias tuberosa) are trouble-free North American natives that produce umbels of bright orange, yellow, or red blooms all summer long. Butterfly weed is appropriately named, as the nectar and pollen rich flowers attract hummingbirds and hordes of butterflies, bees, and other beneficial insects throughout the blooming season. Do you want to know more about how to grow butterfly weed? Read on.

Butterfly Weed Characteristics

Butterfly weed plants are milkweed cousins with tall, clumping perennials that reach heights of 12 to 36 inches (31-91 cm.). The blooms appear atop fuzzy, green stems, which are adorned by attractive, lance-shaped leaves. Butterfly weed plants spread by way of seeds, which are released from large pods in early autumn.

Butterfly weed grows wild in a variety of environments, including open woods, prairies, dry fields, meadows, and along roadsides. In the garden, butterfly weed looks great in wildflower meadows, borders, rock gardens, or mass plantings.

How to Grow Butterfly Weed

Growing butterfly weed requires very little effort. The plant, suitable for growing in USDA plant hardiness zones 3 through 9, thrives in bright sunlight and poor, dry, sandy, or gravelly soil with a slightly acidic or neutral pH.

Butterfly weed plants are easy to grow by seed, but may not produce blooms for two or three years. Once established, butterfly weed is drought tolerant and blooms dependably from year to year. Also, keep in mind that butterfly weed has long, sturdy roots that make transplantation very difficult, so locate the plant in its permanent place in the garden.

Butterfly Weed Care

Keep the soil moist until the plant is established and showing new growth. Thereafter, water only occasionally, as butterfly weed plants prefer dry soil. Trim old growth every spring to keep them neat and healthy.

No fertilizer is required and may even harm the plant.

Mealybugs and aphids may cause problems during the blooming season, but both are easily controlled by regular applications of insecticidal soap or horticultural oil.