The monarch population is at an all-time low. Recent estimates of the monarchs that overwinter in Mexico show their numbers are nearly half of what they were a few years ago. For instance, 60 million monarchs arrived in Mexico in 2012, and, only a few years later, the number was down to 33 million.
While there are a number of reasons for this, one of the biggest has to do with something that we gardeners can fix — lack of milkweed.
Evolution of Milkweed
Twenty years ago, common milkweed was exactly that — common as dirt in every field in the vast stretch of the American Midwest and in the East. This was great for monarchs. Since milkweed is their host plant (where adult butterflies lay their eggs), they never had trouble keeping the next generation going.
Then, Roundup Ready crops showed up — crops that could tolerate the herbicide Roundup without being adversely affected. Unfortunately, one of the plants it killed off was milkweed.
You might not realize just how much milkweed has been affected. Common milkweed still thrives along roadsides today, but it’s been wiped out in millions of acres of agricultural fields. This is why researchers are saying monarchs are in danger — the next generation is running out of food and places to lay their eggs.
Lend a Hand
Luckily, lots of gardeners are helping to fill the gap. Growing common milkweed is a cinch. Just plant it, water it, and wait for the monarchs. With a fragrance as sweet as honey, it’ll attract clouds of nectar-seeking butterflies, as well as egg-laying monarchs. Started from seed, common milkweed can take a few years to flower; started from plants, it’ll settle in faster and soon start to spread via running roots.
With more than 100 species of milkweeds (Asclepias) native to North America, we could fill our gardens with nothing but these fascinating plants. Only a few species are widely available, though, including bright orange butterfly weed (A. tuberosa) and rose-pink swamp milkweed (A. incarnata). Recently, common milkweed (A. syriaca) has soared in popularity as gardeners become more aware of the monarch butterfly decline.
If you like planting outside of the box, there are some little known milkweeds (below) you might try. So go forth and plant milkweed! The next generation of monarchs need your help.
Little Known Milkweeds
Monarchs will use any milkweed as a host plant, so mix it up with common varieties and these not-so-common options. Also, get to know the native plants in your area, and shop native plant nurseries or online retailers. Here are a few varieties to look for:
- Green milkweed (A. viridiflora)
- Heartleaf milkweed (A. cordifolia)
- Narrow-leaved milkweed (A. fascicularis)
- Poke milkweed (A. exaltata)
- Prairie milkweed (A. sullivantii)
- Purple milkweed (A. purpurascens)
- Sand milkweed (A. arenaria)
- Showy milkweed (A. speciosa)
- Spider milkweed (A. viridis)
- Tall green milkweed (A. hirtella)
- Wavy-leaved milkweed (A. amplexicaulis)
- Whorled milkweed (A. verticillata)
- Woollypod milkweed (A. eriocarpa)