There are joys in gardening that go beyond the pleasure we find in the beauty of plants – and in succeeding in the challenges of growing them successfully. A large one is the variety of wildlife plants attract, which range from birds to butterflies, as well as sometimes less-welcome creatures like deer. Butterflies in particular are fascinating, and probably the most well-known to most gardeners is the Monarch butterfly (Danaus plexippus), whose large size and bright colors attract immediate attention. The amazing story of their annual migrations, and threats to their habitats and food sources, has made many gardeners interested in supporting these creatures, and as many already know, milkweed plants (Asclepias) are vital foods for them. If you want to effectively help keep this beautiful creature with us, let’s learn more about the most effective ways to do that.
The most striking feature of the life of Monarchs is their annual two-way migration. In late summer and early fall, butterflies in the north head south, often covering thousands of miles. Divided by the Rocky Mountains, those to the east head for the Mexican state of Michoacán, where millions overwinter in the pine and oak trees of the Mariposa Monarca Biosphere Reserve, while others go to Florida. Not all of them make it, and end up overwintering around the Gulf of Mexico and as far north as Virginia Beach. West of the Rockies they spend winter in several locations in southern California. During these long flights they stop to rest and feed, and can be helped by having suitable flowers for them in your fall garden – more on this later.
In spring they mate and head north again, but they take several generations to do this, so that by the time they arrive in Canada those butterflies are perhaps the 4th generation of those that were in Mexico. During that period there is the need for food for their caterpillars.
Growing a Garden for Monarchs
You can see from this that both caterpillars and adults need food, so to create a successful monarch garden you need to consider both of these. Let’s start with adults, who can feed on a wide range of plants, and since in many areas they are present for long periods, having a succession of plants for them is a great idea. Here are some suitable garden flowers that we can love, and they will too.
Flowers for Adult Monarchs
Too well known to need describing, lilac bushes are spring flowering, so they are great for welcoming back the first arrivals, who follow spring as it travels north. You can grow the larger French lilacs, with their spectacular flower heads, or smaller varieties of Asian lilacs, some that re-bloom in late summer. Since the Monarchs are attracted by color, not just scent, it is likely that it won’t matter what types you grow.
Bee Balm (Monarda)
The brilliant reds and pinks of these perennials bring lots of color to your garden, and flower in summer. They thrive in moist soil.
Joe-pye Weed (Eupatorium)
These large perennials are great at the back of borders and beds, or in wild-flower settings. They are native to North America and have big flat heads of pink flowers in late summer.
Blazing stars (Liatris)
With their bold spikes of purple-pink flowers, Liatris are great for summer color, and loved by all kinds of butterflies.
You can’t have too many Echinacea, one of the showiest of our native wild-flowers, and available in all kinds of modern varieties, all of which attract Monarchs. The perfect garden flower for sunny spots, and in bloom through summer and into fall.
Golden rod (Solidago)
Usually dismissed as a weed, there are ‘tame’ varieties of this perennial wild-flower, that look great in gardens – or just grow it in a rough part of your yard, along with thistles, clover, and alfalfa, all of which are magnets for Monarchs.
All the asters are essential if you want flowers in fall, and blooming late they can be vital for the survival of Monarchs passing through your neighborhood on the way south.
Milkweed and Monarch Caterpillars
One of the interesting things about Monarchs, and part of the reason they are threatened, is the exclusive food of their caterpillars – milkweed. There are several species that grow wild all across America, and a lot of research has been done on which ones females prefer to lay their eggs on, and which give the best chance of the caterpillars maturing into adults. Fortunately for gardeners, the two main perennial species that are grown in gardens are both pretty equal in their value, and both rank among the best species for Monarch survival. It’s worth noting that adult Monarchs also feed on the flowers of these plants.
Asclepias tuberosa – Butterfly Weed
The common name says it all, and this perennial is not only showy and attractive in any garden, it attracts not just Monarchs, but many butterflies, all drawn by its vibrant orange flowers, but especially by its profuse nectar production. Forming a rounded clump of many stems, it is also very tolerant of dry soils – a big bonus in this era of reduced garden watering. The variety ‘Hello Yellow’ is similar, but with yellow blooms instead of the normal orange, but that doesn’t seem to put off the caterpillars.
Asclepias incarnata – Swamp Milkweed
If you have a damper garden, or areas of moist soil, then you can grow this milkweed, which is just as popular with Monarchs. It will grow happily in ordinary conditions too, but not so well in dry soils as Butterfly Weed will. The wild type has purple-pink flowers, and can grow as tall as 5 feet, so put it at the back of your perennial garden. There are several varieties, particularly ‘Ice Ballet’, with white flowers.
Mexican Milkweed (Asclepias curassavica) – one to avoid!
You will often come across this plant at a garden center, which is easy to recognize by its two-tone flowers, typically orange and yellow. At one time it was often the only milkweed available, but today it is easy enough to avoid. When their was first an interest in helping out Monarchs, many gardeners innocently planted this one, but it was a project that backfired. There are two issues with growing this, and both are good reasons not to. First, it stays green and bushy when grown in southern Texas and along the Gulf, so Monarchs tend to stay there, breeding on these plants, rather than heading further south.
There is also a more subtle problem with this plant. There is a dangerous single-cell parasite called ‘OE’ (Ophryocystis elektroscirrha) that is found on milkweeds. Caterpillars who eat infected plants produce weak adults, who usually die on the southward migration. If they don’t migrate the stay alive, passing the parasite on with their eggs, so that it spreads more widely, and ends up killing many more Monarchs that it would had they migrated. So growing this plant where it won’t die down is going to create serious problems, and should be avoided.
Of course, further north, you can grown this one as an annual, but for durable perennial and wildflower gardens, it isn’t a good choice.
A Garden fit for a King
You can see that it’s possible to provide food for both adults and caterpillars of the Monarch butterfly, without reducing the beauty and interest of your garden at all. You don’t need to dedicate part of it to ‘weeds’ to help them, since many great garden plants are used by adults, and a variety of milkweeds make terrific garden plants too. If only all problems were this easy to solve.