Gardening
How you can plant a garden this spring that will help at-risk butterflies thrive
The Monarch and the Milkweed: how you can plant a garden to help at-risk butterflies thrive
They are an odd couple, the monarch and the milkweed. One is the most adored and admired of butterflies, with an epic migration and a royal moniker; the other’s a rough and toxic lowlife, excluded from the polite company of better gardens everywhere. And yet it is the thoroughly unpleasant nature of milkweed (genus Asclepias) that sustains and ultimately protects the eggs, caterpillars and butterflies throughout the monarch’s entire life. Right now, monarchs need all the help we can offer.
The monarch (Danaus plexippus) is famed for its annual two-way continent-spanning migration. And every year about this time, researchers and fans of the monarch butterfly wait in hope and fear for results from two crucial surveys. These two censuses, taken of the dense overwintering population in Mexico and California, together offer a picture of the health of these dwindling pollinators. The survey of western monarchs that winter largely in California (their annual range is northernmost Mexico to Idaho and Oregon) had bad news: California’s overwintering monarch population has declined 86 per cent compared to last year, which itself was one of the lowest ever. It is part of a longer-term downward trend: in the 1980s, an estimated 4.5 million of them overwintered there. The numbers for 2018: fewer than 30,000.
In late January, results of the census of eastern and central Canada’s monarchs that overwinter in a forest in Mexico were the best in 12 years. Encouraging perhaps, but experts are no less concerned: levels are still 90 per cent lower than when the count began in 1975. And the root causes have continued: extensive herbicide use, devastating pesticides, crop intensification, increased wildfires and worse droughts, all in the context of climate change.
As you begin to plant your garden this year, think of the monarch… and think about planting milkweed. It doesn’t wholly deserve its gnarly reputation. Handled and planted appropriately, using the milkweed species native to your area, they can make a fascinating addition to your garden.
There are many nectaring plants beneficial to monarchs native to your area, but none offers the benefits that milkweed does. Monarch caterpillars can eat only milkweed; eggs laid on any other plant do not survive. And the nastiness is part of what is so beneficial to these delicate and seemingly vulnerable creatures. As caterpillars, monarchs consume nasty-tasting toxins found in milkweed, making them utterly repellent to predators. The eventual butterflies are also unpalatable to any would-be predators. Birds see the bright yellow caterpillar or the high-viz orange, black and white wings like a big highway caution sign.
True, the milky sap that leaks from the leaves and stem is mildly noxious. But some types are worse than others, so choose a plant with a milder temperament. Simple steps like washing your hands or using gardening gloves will prevent any irritation to humans, and pets aren’t interested in consuming these plants — they taste too awful.
There is plenty of choice, with about a dozen native species of milkweed throughout southern Canada (though rare in Newfoundland and Labrador and all too common in Nova Scotia and Manitoba, where “common milkweed” is banned as a noxious weed). When choosing a type for your garden, opt as most do for the slower-growing types. And to prevent your milkweed from spreading, snip the flower heads once droopy; they are just starting to make seeds. You can check out CWF’S native plant encyclopedia online to choose the right plant for your garden’s specific conditions. Gardeners in Ontario and southwestern Quebec might think about the Asclepias tuberosa, better known as butterfly weed. (Not to be confused with butterfly bush, Buddleia, an unpleasant invasive.) Suited to sunny well-drained areas, it blooms in late spring and summer. Butterflies, particularly monarchs, are drawn to its vivid orange flower.
Besides planting pollinator-friendly plants in your garden, there are other ways to attract them: use a variety of plants that bloom from spring through fall so there’s always an attractant; don’t use pesticides; create a sea-salt lick; and consider leaving sumac, elderberry and raspberry stems along with snags or stumps for habitat. It is these types of gestures in your plot, in the local schools’ and libraries’ gardens and in your municipalities that together can make a meaningful difference for a beloved species in great distress.
For more information on these and other ideas and tips, and to learn about how your garden can qualify for CWF Wildlife-friendly Habitat status, visit