Text and photos ©Nancy J. Ondra
I hardly need a calendar to know that summer’s here at Hayefield. When the third week of June arrives, the milkweeds begin to bloom.
The photo above shows a clump of purple milkweed (Asclepias purpurascens) near the end of my driveway. I fell in love with this species from a photo at a plant lecture about 10 years ago. I couldn’t find plants for sale at the time, so I imported seed from the only source I could find (in Britain), and failed to get it to germinate. About five years ago, I finally scored the three plants that make up the current clump, got them established, and congratulated myself heartily.
My smugness lasted only a year or two, when I realized that several plants of purple milkweed were already growing in the hedgerows on my parents’ farm next door. Then last year, I found quite a few established plants growing in my own meadow out back.
I knew well that the meadow was already home to several large patches of common milkweed (A. syriaca), because those plants are hard to miss: they’ tall (to about 5 feet, instead of the 3 feet of the purple milkweed), and all parts of the plant are somewhat larger.
Common milkweed is also distinctive for its vigorously spreading habit, which is fine in a meadow but a problem in a bed or border. I’ll note that my three original plants of the purple milkweed have been growing in one spot for about 5 years now, and they’ve shown no sign of creeping, nor do those growing in our meadows and hedgerows. So if you’re thinking of adding a milkweed to your garden, A. purpurascens would likely be a better choice than A. syriaca.
Butterfly weed (A. tuberosa) is another species that’s garden-safe, in that it’s a clumper instead of a spreader. I’ve seen it growing wild less than a quarter-mile from here, but I think the soil right here normally too wet for it. It does grow happily in the meadow mix that I sowed on my sand mound (aboveground septic drainage field), however.
The gravelly substrate and raised position seem to suit it very well.
It still amazes me to see many dozens of these growing untended in the meadow, when I’ve tried and failed so many times to bring them into the garden proper. That orange color would be so perfect for the front garden! Well, at least I can enjoy it somewhere. (By the way, I’ve found that the annual ‘Cosmic Orange’ cosmos and ‘Profusion Orange’ zinnias are much more adaptable choices for getting that intense orange in the garden.)
Another well-behaved species that grows naturally in my meadow is swamp milkweed (A. incarnata), in various shades of pink. I haven’t tried to grow this one in the garden here, but I remember having the white ‘Ice Ballet’ in my previous garden and delighting in the sweet scent. Swamp milkweed usually starts blooming about a month later than the others, though, more toward mid- to late July.
I’m not the only one who enjoys having the milkweeds around here. From the time they open until the flowers drop off, they’re alive with all kinds of insects: butterflies (including skippers)…
…lots of bees…
…lots of milkweed buds…
…and, of course, the larvae of monarch butterflies.
And that brings me to a question maybe some of you can answer. It seems to me that within the past few years, I was at a native-plant meeting where a speaker claimed that we should not grow milkweed species that are not native to our region. I believe the reasoning had to do with the various milkweed species differing in the amount of the toxic compounds that make the larvae unpalatable to other critters – that if the monarchs fed on non-native species, they might not get the needed protection and could be more vulnerable to predators.
I know this speaker made sense to me at the time, but I think I must have lost some of the details over the years, because I can’t get my mind around the reasoning now. I’ve found one reference to a non-native milkweed possibly being too toxic for the monarchs (see the March 14, 2003 entry at Our Backyard Observations about tropical milkweed [A. curassavica]), but no warnings about non-natives providing insufficient protection for the larvae. I’d really like to figure this out, because I do remember thinking that I ought to get rid of the showy milkweed (A. speciosa) that I acquired and nurtured to bloom stage.
It’s native to the western half of the U.S., but I’m in Pennsylvania, so I figured I’d better remove it, even though the blooms are fantastic. Well, I tried, but this little bugger has very persistent spreading roots, so there are still pieces of it throughout my holding beds. If I can convince myself I’m not endangering the monarchs by moving it to the meadow, I’d love to keep it. So, anyone have any insight on the issue?