If I wanted to attract butterflies and had room for only one nectar plant, I would choose butterfly weed (Asclepias tuberosa).
Butterfly weed is not only a terrific nectar plant for many butterfly species, but is also the sole host plant for the monarch butterfly, whose numbers have been decreasing so steadily that they’ve reached “Near Threatened” status with the World Wildlife Fund (WWF). In cold weather, monarchs migrate between more than 1,000 miles between the U.S. and Canada to forests in central Mexico, where they hibernate until it’s warm enough to head back north. Earlier this week, Omar Vidal, CEO of WWF in Mexico, issued a statement urging the eradication of illegal logging in Mexico’s forest cover and asking that habitat loss be tackled in the U.S. and Canada, as well.
In the meantime, the Perennial Plant Organization has selected Asclepias tuberosa as its Plant of the Year for 2017. Shoot, they’re even selling tee shirts to promote this North American native!
With its striking, deep-green foliage and vibrant orange blooms, butterfly weed is a real showpiece in the garden. It grows 12 to 30 inches tall. There’s a newer, yellow variety called ‘Hello Yellow.’ I planted one in my garden last summer, and it lasted till frost, when it went dormant. I’ll see if it emerges this spring.
Several Colorado gardeners have told me they’ve been unsuccessful in growing butterfly weed in our heavy clay soils. Anticipating problems but being curious, I bought a #1-sized plant from a local nursery about five years ago. I amended the soil with organic matter before installing this beauty, and, surprisingly enough, the plant seemed very happy. It popped up reliably the following season.
For those of you who haven’t had luck with butterfly weed, I have a few suggestions:
- Install a healthy, #1-sized plant from a reputable nursery. Smaller plants don’t seem to establish as well, according to some of my fellow gardeners.
- Be aware that butterfly weed has a tap root, and if you damage it in any way, the plant will die.
- Amend the soil if you have heavy clay. I used compost. Another experienced Colorado gardener suggested using sand or gravel for amending. Good drainage is critical.
- Wait until drier weather to plant it. In other words, don’t plant it in the spring, when there’s more rain. Wait until a summer month.
- Plant your butterfly weed in full sun.
- Keep a close eye out for yellowing leaves. If you see a lot of yellowing, you may be over- or under-watering the plant. Over is more likely. Asclepias tuberosa doesn’t like too much moisture. If you can nurse your butterfly weed through its first growing season, you may be home free. Fortunately, the plant spreads nicely, once established.
There’s an annual butterfly weed, Asclepias incarnata or swamp milkweed, which also serves as a host for the monarch. Swamp milkweed grows four to five feet tall and produces white, pink or mauve blooms.
If you would like to learn more about butterfly gardening, you’re invited to attend my free program, Butterfly Garden Basics, at the Loveland, CO public library, 300 North Adams, on March 29. The program begins at 1pm. Arrive early, though, because I’ve been told that 50 or more people often attend the gardening presentations at this library.