By September, many of the monarch caterpillars we watched earlier in the season have disappeared into chrysalises and emerged as butterflies. Now, the monarchs moving through our region have an incredible journey ahead of them.
They are heading south.
Some will travel thousands of miles before reaching their wintering grounds in Mexico. To make that journey, monarchs need places to stop and feed along the way. They need flowers still blooming when much of the summer garden has begun to slow down.
This is why milkweed is only part of a monarch garden.
Milkweed is essential because it is the only plant monarch caterpillars can eat. Without milkweed, there cannot be another generation of monarchs. Adult monarchs, however, drink nectar from many different flowers. During fall migration, that nectar becomes the fuel they need to keep flying and to build the fat reserves that will sustain them through winter.
Goldenrods, asters, Joe Pye weeds, liatris blazing stars, mistflower, ironweed, boneset, mountain mints, and late-blooming sunflowers can all help provide that fuel.
The goal is not simply to fit every one of those names into the same garden. The goal is to make sure monarchs can find what they need across many different kinds of places.
A Monarch Does Not Travel Through One Kind of Garden
Think about the places a monarch passes through on its way south.
There are sunny roadsides, dry hillsides, open meadows, wet ditches, streambanks, woodland edges, farms, neighborhoods, and small gardens tucked into town. The growing conditions change constantly.
That is part of why plant diversity matters so much.
When we grow native plants suited to the conditions we have, we help fill more of the spaces monarchs pass through. One garden may provide nectar along a sunny, dry stretch. Another may offer flowers beside a creek. Someone else may have the moist, partially shaded edge that connects those two places.
Together, those gardens create a much more useful migration route than any one garden could create by itself.
One Milkweed Cannot Fill Every Space
We often talk about planting milkweed as though milkweed were one plant. There are more than one hundred species native to North America, and they do not all grow in the same conditions.
Butterfly Weed is a great choice for dry, sunny areas. Its deep root system helps it handle heat and drought once it is established. Whorled Milkweed works well in sunny areas with dry to average soil. Its narrow leaves and finer texture make it easy to mix among asters, grasses, blazing stars, and other meadow plants. It also tends to bloom later than several of our better-known milkweeds.
Common Milkweed prefers an open, sunny area where it has room to form a colony. It may not be the best choice for a small, carefully arranged flower bed, but it can be an excellent plant for a meadow, field edge, or naturalized section of a property.
Swamp Milkweed fills an entirely different space. It prefers consistently moist soil and is well suited to rain gardens, low areas, and places near streams or ponds.
Poke Milkweed naturally grows around woodland openings and edges. It tolerates more shade than most milkweeds and gives gardeners with dappled light another way to provide monarch host plants.
All of them are milkweeds. All can feed monarch caterpillars. Their differences allow milkweed habitat to exist in places where a single species could not.
Goldenrod Is Not Just One Plant Either
Goldenrod is one of the most valuable groups of late-season nectar plants, but it is often treated as though every goldenrod were the same tall plant growing along the roadside.
Our native goldenrods fill many different parts of the landscape.
Showy Goldenrod is a good fit for sunny areas with dry to average soil. It forms a more restrained clump than some of the goldenrods people are accustomed to seeing in fields, making it easier to use in a perennial garden or smaller meadow planting.
Grass-leaved Goldenrod has flatter clusters of flowers and is useful in sunny areas with somewhat more moisture. Its shape is different from the arching plumes many people associate with goldenrod, but it offers the same abundance of small, nectar-rich flowers.
Wrinkle-leaf Goldenrod is adaptable across a fairly wide range of soils and can handle some partial shade. Zigzag Goldenrod is especially useful along woodland edges and in shaded gardens, where many of our familiar late-season nectar plants will not grow well.
Goldenrods give us options for dry sun, average garden soil, moist ground, and woodland edges. Planting several species also helps spread their bloom across a longer period instead of depending on one brief flush of flowers.
And no, goldenrod is not usually what is causing your fall allergies. Its heavy pollen is carried by insects. Ragweed, which blooms at the same time and releases lightweight pollen into the air, is usually the real culprit.
There Is a Joe Pye for More Than One Garden
Joe Pye Weed is another name that can refer to several different plants.
Hollow Joe Pye Weed is the towering plant many people picture. It can reach well over six feet in rich, moist soil and produces enormous flower clusters that can be busy with butterflies throughout late summer. It is well suited to large rain gardens, streambanks, meadow edges, and the back of a planting.
Spotted Joe Pye Weed also prefers moist ground and works beautifully in rain gardens, wet meadows, and low areas. It is usually a little more manageable than Hollow Joe Pye, although it can still become a substantial plant.
For a smaller garden, Baby Joe offers the familiar mauve flowers on a plant closer to three or four feet tall. It still prefers consistent moisture, but it can fit into a perennial bed where a seven-foot Joe Pye would be difficult to accommodate.
Asters Can Carry the Garden Through Fall
Asters always make my heart happy in the spring, and a bit sad in the fall, as they herald the coming of winter. With their late, abundant blooms, they may be some of the most important plants we can add for migrating monarchs. Many begin blooming when other perennials have finished, and different species can cover a surprising range of growing conditions.
Smooth Blue Aster and Aromatic Aster are excellent choices for sunny areas with dry to average soil. Aromatic Aster stays relatively compact and covers itself with purple-blue flowers late in the season. Smooth Blue Aster grows taller and mixes beautifully with native grasses, goldenrods, and blazing stars.
New England Aster prefers richer soil with a little more moisture. Swamp Aster can grow in low, wet areas where a dry-soil aster would struggle.
Big-leaved Aster, Drummond’s Aster, and Short’s Aster help bring late-season flowers into woodland gardens and partially shaded edges. Sky Blue Aster and New York Aster give us still more options for open gardens and meadow plantings.
Planting more than one aster is not simply about collecting different flower colors. It extends the bloom season and puts fall nectar into a wider range of places.
Look Beyond the Familiar Favorites
Milkweeds, goldenrods, asters, and Joe Pye weeds give us a strong foundation, but monarchs use many other native flowers during migration.
Mistflower is especially useful in moist soil and partial sun. Its fuzzy blue flowers can continue into October, and a healthy patch creates an easy place for butterflies to stop and feed. It spreads when it is happy, which makes it a great choice for rain gardens, streambanks, and naturalized low areas.
Dense Blazing Star grows well in sunny soil with average moisture. Its upright purple flower spikes are easy to tuck among shorter meadow plants, and blazing stars have been documented as especially valuable monarch nectar sources. Appalachian Blazing Star gives us a shorter option for drier, leaner ground.
Ironweed adds deep purple flowers to moist meadows, streambanks, and larger plantings. Giant Ironweed can become quite tall, while other ironweeds can fit into somewhat smaller spaces.
Boneset belongs in the wetter parts of the garden. Its clusters of tiny white flowers may not be as flashy as an aster or blazing star, but they can attract a remarkable number of butterflies, bees, wasps, and other beneficial insects.
Narrow-leaved Mountain Mint is a good choice for sunny, drier soil. It produces an abundance of small flowers and is often covered with pollinators. Wingstem, Tall Tickseed, Maximilian Sunflower, and other late-blooming members of the sunflower family can help keep larger, sunny areas full of nectar.
The right plant depends on the place.
Each planting fills a different part of a monarch's route.
Plant the Place You Have
Plant several of the same species together when you can. A group of flowers is easier for a passing butterfly to see and allows it to gather more nectar without using as much energy searching. Choose plants with overlapping bloom periods so there is not a long stretch without flowers. Avoid systemic insecticides that can remain in plant tissue and harm caterpillars and adult butterflies.
September is a wonderful time to get native perennials established. The soil is warm, the weather is becoming gentler, and roots can continue growing after the top of the plant has slowed down for the season.
Milkweed remains one of the most important things we can plant for monarchs. But a monarch carrying the future of its species south needs more than a place to lay eggs.
So consider giving monarchs another place to stop, wherever their journey happens to take them.
