Each spring, monarch butterflies make their journey northward and then begin their return to overwintering sites in Mexico towards the end of the year. Over the course of this epic migration, the butterflies require nectar sources and host plants upon which to lay the eggs of a new generation of offspring. Once innumerable, monarch populations have dwindled in recent years due to the gradual extermination of its host plant: a genus of natives called milkweed. A tenacious weed common to agricultural lands, milkweeds are also toxic to livestock, making them a familiar foe for farmers. The vast cornfields that lay on the midpoint of the monarch’s migration now represent an ecological desert for the butterfly. Stripped of suitable reproduction sites and few places to feed, the traditional autumnal monarch sighting has become more and more rare.
It’s important for us to keep monarchs on the landscape as pollinators to maintain biodiversity. Fortunately, there’s something we can do about it, and the solution begins in your garden. Just as summer’s ample supply of flowers begins to wane, the butterflies start their southern migration. To ensure they get the food they need, monarchs follow the blooming of late summer’s composites, such as goldenrod and aster. Often found along roadside ditches, lawn edges, and old fields, these plants are important nectar sources but are often mowed down or sprayed with herbicide, leaving little for autumn pollinators. To help a hungry monarch, make space in your garden for goldenrod and aster. New England aster comes in every shade of pink and purple imaginable and does well tucked in the back border of a yard, where it can grow to its full imposing height of five feet.
Goldenrods are native throughout North America, so take your pick of large or small, compact or leggy, dry land or wetland species. Each one sports a bright spire of yellow flowers in late summer and early fall, and each flower is a terrific producer of the sweet stuff all monarchs need. If your garden is too small for extra plants, put aside a patch of lawn and let it revert back to native meadow. Nectar-rich wildflowers like aster and goldenrod will naturally reclaim these untended spaces. Even if it’s just a little strip a few feet wide, it can and will make a difference for monarchs and all other pollinators. Other good native plant nectar sources include mountain mint, ironweed, and blazing star.
As with any kind of wildlife gardening, diversity is the goal. Plant flowers for all seasons, beginning in early spring (particularly for gardens in the south) and extending all the way to late fall. Lump flowers en masse, so their blooms will be visible from a great distance, and leave wet open spaces for mineral licks, where butterflies can gather and suck up essential nutrients from the soil. Cultivate clusters of important host plants and eventually, with a little luck and persistence, we will save these important pollinators for many years to come.
Monarch Nectar Sources and Host Plants
New England aster
New Jersey tea