Milkweed, also known as asclepias, is native to North America, and one of them, Asclepias tuberosa, has been named Perennial Plant of the Year by the Perennial Plant Association this year. This plant, sometimes known as butterfly weed or butterfly milkweed, has bright orange flowers that attract a variety of butterflies and bees with nectar and pollen. Butterfly weed’s leaf isn’t a favorite meal of monarch caterpillars, but it can help them survive. This drought-tolerant plant prefers a dry, sunny environment and is hardy in Zones 3 to 9.
Upright stems with clusters of bright orange flowers contrast attractively with the shiny green leaves of butterfly weed. Unlike other members of the genus, the stem sap is not milky. This milkweed is not invasive since it does not spread by runners like common milkweed (Asclepias syriaca). Although deer are not attracted to butterfly weed, aphids can be an issue in gardens and greenhouses.
This plant is expected to be in great demand in the next years. Butterfly weed blooms readily the first year after seeding, but there are a few crucial elements to remember if you want to grow it professionally.
This species displays some of the most extreme photoperiod reactions we’ve ever seen. It’s an obligatory long-day plant, which means it has to flower during long days. When grown at an average of 68° F, plants develop quickly under photoperiods of 14 hours or more, and begin flowering about eight to nine weeks after transplant. Plants that are exposed to photoperiods of 12 hours or less, on the other hand, die dormant after a few days (Figure 1, pictured above). Leaves droop, shoot growth appears to stop, and existing flower buds may suffocate (Figure 2). Unfortunately, simply reverting to longer days will not return the plants to active growth. A nine-week or longer cold treatment is required to break this dormancy; in our testing, all dormant plants treated to 41° F for 15 weeks bloomed.
It is critical to provide long days to plants in order to keep them actively growing. We propose at least 16 hours of daylight or four hours of night disruption illumination. A minimum intensity of 2 molm2s1 should be delivered by photoperiodic illumination. Use incandescent lights or LED bulbs intended to control blooming that emit both red and far-red radiation. Maintain these extended photoperiods for plants until natural daylengths reach at least 14 hours.
Butterfly weed has a huge tap root, making transplanting or dividing established plants difficult. It’s critical to utilize a well-drained medium in container production, so consider adding more perlite to a standard peat+perlite mix. During production and cold treatments, be careful not to over-water. The taproot attracts fungus gnat larvae, so keep an eye on the roots if your plants aren’t doing well.
Butterfly weed can grow up to 3 feet tall in the wild, but in container production, our plants were only 12 to 18 inches tall when they first bloomed. Sprays of daminozide (e.g., B-Nine, Dazide), paclobutrazol (e.g., Piccolo, Bonzi), and uniconazole (e.g., Piccolo, Bonzi) are apparently helpful for height management (e.g., Sumagic, Concise). To help fill out containers, use many plugs per pot or squeeze seedlings soon after transplant.
Is Asclepias invasive?
“It’s sad that such a lovely and vital plant in our North American ecology is labeled as a weed,” Miriam explains. The invasiveness of common milkweed (Asclepias syriaca) is the basis of the plant’s negative rep. It was also on the Ministry of Natural Resources’ noxious weeds list in Canada.
The good news is that there are milkweed varieties that do not spread. “Red milkweed (Asclepias incarnata) and butterflyweed (Asclepias tuberosa) are also good for monarch butterflies,” explains Miriam. “Both of these plants serve as host plants for adult monarch butterflies as they lay eggs, as well as food sources for the larvae” (caterpillars). These two alternatives do not have rhizomes and are used by monarch butterflies just as frequently as common milkweed.”
Red milkweed will grow in any soil type, according to Miriam, but it favors medium to moist soils. It prefers direct sunlight (though it will tolerate a bit of shade). “Butterflyweed tolerates some shade as well, but prefers sand or loam for its soil. “It’s best if the soil is dry to medium,” she says.
And, according to Miriam, you can still plant common milkweed, especially if your soil is dry and clay. She advises planting it with a mix of other native flowers and grasses that will take up the different amounts of soil. “Common milkweed spreads through rhizomes (underground runners or roots), which is why it can grow so quickly. You provide little room for the rhizomes to migrate by putting it among a dense planting of other native species.”
Other types of monarch nutrition that you can include in your garden, according to Miriam, are liatris, goldenrod, and asters.
Unfortunately, I haven’t seen many monarch butterflies flitting around in my garden in recent years. I’ve seen a few other species, particularly near my buddleia, but I want to make sure the monarchs have a safe haven in my garden as well. I quickly shared the #GotMilkweed message with other gardeners so they might add it to their list of must-plants. “Anything that puts the issue of native pollinator health to the forefront is a good thing,” Miriam said, noting that the monarch butterfly issue is being brought to light thanks to David Suzuki and his team’s efforts. “In a way that only David Suzuki can, he’s increasing awareness, and it’s proving to be a positive step forward.”
Which milkweed is not invasive?
Identifying the “best” necessitates a mix of geography, butterfly preferences, and plant performance. Different milkweed plants will thrive in different parts of the country, while butterflies will thrive in other areas “Favorite” is a term that varies by region (and even in the same garden from year to year).
In North America, there are approximately 100 species of milkweed, although not all of them are used by monarch butterflies. I’ll concentrate on well-known plants that have seed, are known to attract Monarch butterflies, and are easy to grow in the garden (with a few exceptions that I will point out in the descriptions below).
This list is not exhaustive, and I recommend that you experiment with a few different varieties in your garden to see what grows well and to provide your Monarchs with a variety of options as well as backups. Every year, many butterfly garden enthusiasts have three or more distinct species of milkweed.
Tropical Milkweed (Asclepias curassavica)
In most gardens, tropical milkweed is most likely the Monarchs’ favored milkweed. It is not native to the United States, but it has established itself as a perennial in zones 9-11 (perhaps 8b as well). However, because this plant grows quickly and easily from seed and flowers continuously throughout the summer, it is widely used as an annual in the United States and Canada.
It does not need to be cold stratified like many other milkweed seeds, and it produces a large number of collectable seeds each year. To gain a head start on the butterfly season, the seeds can be spread during the winter or started inside early in the spring.
In a sheltered place, this milkweed plant may reseed itself in your garden or even return in the spring. Many butterfly gardeners recommend it, and it’s also a fantastic nectar plant for a variety of other butterflies.
Swamp Milkweed (Asclepias incarnata)
Swamp milkweed, as well as the following few plants listed below, are known to be favorites of monarch butterflies. It’s impossible to choose one over another as an overall Monarch “favorite” because of native ranges, geographies, and individual garden differences.
Asclepias incarnata is a perennial that may be grown in zones 3 through 8. (some reports include zone 9). Although it is a swamp plant, once established, it will thrive in moderately moist circumstances.
If cold stratified before beginning indoors or sown in the Fall/Winter, it grows quickly from seed. With the exception of the west coast, this milkweed is native throughout the majority of the United States and eastern Canada. It is a lovely addition to a butterfly garden and serves as a nectar plant for a variety of butterflies.
Swamp milkweed isn’t as invasive as other milkweeds, and it stays out of your way in the garden. Swamp Milkweed has photographs, more extensive information, and seeds/plants for sale.
Swan or Balloon Plant (Asclepias physocarpa)
Swan plant, Balloon plant, Oscar, Family Jewels, Hairy Balls, and Giant Swan Milkweed are some of the common names for Asclepias physocarpa (also known as Gomphocarpus physocarpus).
Monarch butterflies love it, and the seed pods are round balls, making it a unique milkweed. The flowers are pleasant but unremarkable; however, the seed pods make this milkweed plant a conversation starter! The pods work well in dried arrangements as well.
Milkweed from the Family Jewels family is native to South Africa. In zones 9-10, it is a fragile perennial that can grow weedy and invasive in tropical environments. In cooler climates, it is planted as an annual. In the fall, seeds can be harvested and transplanted in the spring.
This milkweed is a big, tree-like plant that grows to be 5-6 feet tall. Visit Asclepias physocarpa to see more photographs, receive more information, or buy plants/seeds.
Purple Milkweed Plants
Asclepias purpurascens and Asclepias cordifolia are two separate species of milkweed with the common name “Purple Milkweed.” Heart-leaf milkweed is another name for Asclepias cordifolia. Heart-leaf milkweed is native to California, Nevada, and Oregon, whereas Asclepias purpurascens is native to the United States’ central and eastern regions, as well as Eastern Canada.
Both of these plants are sometimes preferred by butterfly gardeners due to their distinct colour, with darker violet or purple flower hues than most other milkweeds. They are very easy to control and are well mannered in the garden. Asclepias purpurascens resembles common milkweed (described below), but its blooms are much darker and it behaves much better in the garden.
Heart-leaf milkweed is hardy in zones 7-10, while Asclepias purpurascens is hardy in zones 3-8.
Heart-leaf milkweed has more information, photographs, and seeds/plants available here and here.
Is Asclepias tuberosa good for monarchs?
Our native Butterfly Weed, Asclepias tuberosa, has long been a favorite in the farm’s borders, beds, and meadows. It’s gotten a lot of attention in recent years since it’s an important source of food for Monarch butterflies during their larval stage. (Visit the Xerces Society for Invertebrate Conservation’s website for additional information on its work in Monarch butterfly conservation.)
The Perennial Plant Association named it the 2017 Perennial of the Year this year.
Asclepias tuberosa (pronounced uh-sklee’pee-us) is a vividly colored flower that provides four seasons of interest in the garden, in addition to supplying food for Monarch butterflies and nectar for a broad range of pollinators. It grows to a modest 1- to 2-foot height and is hardy in zones 4 through 9S and 10W, making it suitable for the edge of the border. From July to September, the plants produce clusters of brightly colorful, nectar-rich orange blossoms. (The enhanced native species Asclepias tuberosa ‘Hello Yellow’ grows 23 feet tall and produces yellow blooms.) These plants can withstand drought, thrive in poor soil, and are resistant to deer.
Seedpods of Asclepias tuberosa offer beauty to borders and beds as autumn approaches. The papery seeds fill the narrow, elegant pods. The pods split apart as the season continues, and the seeds, which are connected to silky white parachutes, scatter in the breeze. The plant’s pale, empty husks remain, and as winter approaches, the pods are covered in frost and then swirling snow, looking wonderful. Asclepias tuberosa was incorporated in Dutch designer Piet Oudolf’s design for New York City’s High Line because of its winter beauty.
“The complex flowers are stars of the garden in the summer, but the empty husks of the seed pods remain a vital element of the winter garden as well,” according to a 2014 post on the Friends of the High Line site. Dry and somewhat twisted from the drying process, these oblong golden-gray husks are dry and slightly twisted. When the light is right, the outsides are rough and gray, with a trace of gold. The interiors are a soft white, like the silky hairs that captured the wind and carried the seeds away. During the deep freeze of winter, these pods top the stem’s skeleton, producing a subtle, textured beauty. “The skeletons of the plants… are equally as significant as the blossoms,” High Line planting designer Piet Oudolf said of these structures.
Keep a few things in mind before growing Asclepias tuberosa. It prefers full light and well-drained soil to thrive (sandy soil is ideal; clay and heavily enriched soils are not). After planting, water the plant thoroughly, then wait until it begins to wilt. If your Asclepias tuberosa starts to develop yellow, chlorotic-looking leaves, you’ve over-watered it.
Because some perennial Milkweed kinds are among the last to emerge from hibernation in the spring, you should note their location so that you don’t accidentally plant something on top of them.
As with many other garden additions, Asclepias tuberosa looks best when planted in groups of three or more. Showcase the vivid brilliant orange blooms of Salvia ‘May Night’ and Liatris ‘Kobold’ alongside the deep purple flower spikes of Salvia ‘May Night’ and Liatris ‘Kobold’ to create an eye-popping juxtaposition of hues and flower forms. Our head gardener has planted orange-flowering Asclepias tuberosa among a sea of other orange bloomers including Zinnia ‘Profusion Orange,’ Echinacea ButterflyTM ‘Julia,’ ButterflyTM ‘Postman,’ or Prairie PillarsTM ‘Flame Thrower,’ and Helenium ‘Short ‘n’ Sassy,’ for a tone-on-tone effect. The orange flowers of Festuca glauca Beyond BlueTM go well with decorative grasses like the 18″30″ Pennisetum ‘Hameln’ and the blue spiky foliage of Festuca glauca Beyond BlueTM in meadow gardens. They’re also a great match for Amsonia hubrechtii, a plant with green needle-like foliage that turns yellow in the fall.
Be warned that once Asclepias tuberosa has established itself, it does not like to be relocated. The plants produce deep taproots that should be left alone once planted, so place it carefully, leave it alone, and reap the advantages of this extremely beneficial plant.
How do you keep milkweed from spreading?
Spread a 3- to 4-inch layer of mulch over the area where milkweed was removed to prevent it from resprouting. Milkweed needs a lot of sun to develop, and it won’t grow if it’s shaded. Milkweed is shaded out by a dense stand of flowering plants or shrubs, which helps keep it from regrowing.
Does milkweed spread fast?
Milkweed is a favorite of Monarch Butterflies and will attract a swarm of them to your garden or meadow. It can be difficult to start, but once established, it will survive for years and spread rapidly. Perennial.
Is butterfly bush invasive?
Buddlejadavidii (Butterfly Bush) is a sure-fire attention-grabber. Its fragrant conical bloomstypically draped with fluttering butterflies and swarming beesare hard to miss in our region’s gardens and landscape plantings.
Butterfly Bush is an invasive species that can harm the health of our local ecosystems, despite its attractive appearance, hardiness, and apparent benefit to butterflies and other pollinators.
Should I cut back milkweed in the fall?
During the fall and winter months, trim the milkweed stems to about 6 inches in height to dissuade monarchs from establishing winter-breeding colonies. Cutting back the milkweed will also aid in the removal of any OE spores that may be present. As the leaves re-sprout, re-cut the milkweed every several weeks. Because tropical milkweed dies back naturally when it freezes, it may offer fewer problems in the northern monarch breeding region.
These instructions do not apply in south Florida (south of Orlando), where a distinct, non-migratory monarch population has existed for many years. In this location, however, native milkweed planting is still recommended.
Should I plant milkweed in my garden?
Although native milkweeds do not host OE, putting them too close to the monarchs’ overwintering habitats can disrupt their flight patterns. The butterflies may not migrate before laying their eggs if you plant it too close to where they spend the winter, disrupting their typical route and causing year-round habitation.
Because monarch butterflies aren’t intended to breed at the coast, there’s no need to spread milkweed to aid them. Winter-breeding monarchs appear to have a greater mortality rate, shattering the migration miracle. According to some scientists, monarchs themselves are not endangered, but monarch migration is.
So, if you reside on the coast of California, plant nectar plants to help monarch butterflies migrate to and from overwintering areas; don’t plant milkweed. Planting milkweed within 10 miles of an overwintering site is not recommended. If you live inland, please plant native nectar plants and milkweed to help monarch butterflies migrate away from overwintering places.
Because there isn’t enough space to cover everything here, here are other places to visit for more information, including plant lists: