These swamp rose mallows were photographed in bloom at Heritage Conservancy’s Aldie Mansion.

Whether you are starting a new garden, expanding an existing one, or filling in a bald spot, many gardeners find themselves in need of beautiful plants that will fill a large area quickly. When selecting aggressive, fast-growing plants, going native is crucial. There are two benefits to choosing native over non-native plants: 1) you avoid planting a future invasive species that may become a nightmare to contain and wreak havoc on the local ecosystem, and 2) you quickly create an abundance of food and shelter for native wildlife like birds and butterflies. To help you find the right native plant for your garden, here is our rundown of some of our favorite native fillers.

But first, some quick definitions:

Invasive – A species of plant, animal, fungi, or other organism that 1) is not native to the place it is found; 2) can grow/reproduce rapidly; and 3) causes some combination of environmental, economic, and human health harm. These species can be introduced both intentionally and unintentionally. Examples include tree-of-heaven, burning bush, multiflora rose, mile-a-minute vine, orange daylily, stilt grass, emerald ash borer, and spotted lanternfly.

Ornamental – A species of plant that is not native to the place it is found, has been intentionally planted for primarily decorative purposes by people, and has not escaped from cultivation to grow in the wild. These species tend to have a fairly neutral impact on local ecosystems, not contributing much but not really harming anything either. Examples include Norway spruce, boxwood, crepe myrtle, yew, begonia, chrysanthemum, daffodil, dahlia, lily-of-the-valley, lavender, marigold, pansy, peony, petunia, and tulip.

Aggressive – A colloquial term that, in this article, refers to plants that grow and spread quickly, often growing densely as well. In a garden, it is a good practice to place plants of similar “aggression levels” together so that neither one smothers the other. This term does not refer to where the plant species originates or its value to wildlife. Examples: the rest of this article!

Native – A species of plant, animal, fungi, or other organism that originated in the place where it is found. Determining which plants fall within the native category for a given place depends on the type and quality of historical data available, the reference period being used, and how spatially precise the categorizer is. Examples: the rest of this article! Plus, see our other Nature Notes to learn more about other cool native species.

The Mighty Mint Family

These tall, showy members of the mint family offer a variety of colors and bloom times while sharing the mint family’s common propensity to grow rapidly. If you want your garden to support local pollinators, offer those insects (and hummingbirds!) a variety of flowers that bloom throughout the year. It’s a great tactic. Mountain mint, wild bergamot, and bee balm typically all grow best in full sun but can handle a variety of soil conditions depending on the exact species you choose. Some mountain mints can also tolerate a bit of shade.

Spring Yellows (and Some White)

Golden Alexander (Zizia aurea)

Golden Alexander is a beautiful, adaptable plant that can handle both occasionally dry and occasionally wet soils, as well as full sun and light shade. Its explosion of yellow flowers blooms in May. Its leaves feed the caterpillars of black swallowtail butterflies, whose stunning adult forms can eventually add beauty to the garden as they sip nectar from other flowers blooming later in the year.

Golden Ragwort (Packera aurea)

Golden ragwort is a great pop of yellow to add to shadier sites, especially medium to wet ones. Blooming a little earlier than Golden Alexander, golden ragwort is a great source of food for emerging pollinators. Throughout the growing season, golden ragwort’s dark green leaves create a pleasing, low-growing mat that spreads quickly, filling in even the smallest gaps.

Canadian Anemone (Anemone canadensis)

Growing in similar conditions to golden ragwort, Canadian anemone offers another later-blooming option. Its white flowers come out in late spring and early summer and put on the best show when grown in part sun. Another name for Anemone plant species is windflower because their flowers sway in the wind in a way that is reminiscent of underwater anemones. Canadian anemone also offers interesting, vaguely star-shaped leaves that remain throughout the warm season.

Summer Pinks and Purples

Common Milkweed (Asclepias syriaca)

Common milkweed may not form thick clumps and mats the way some of these other fillers do, but its ability to self-sow and pop up in just about any field has earned it a spot on this list. Like goldenrods, you may not even need to buy this one; just keep an eye out for it and let it do its thing. Common milkweed, like the other native milkweeds, supports a long list of specialized beetles and lepidopterans (i.e., butterflies and moths).

Swamp Rose Mallow (Hibiscus moscheutos)

Swamp rosemallow looks like it belongs somewhere tropical, but lucky for us, this member of the hibiscus genus is native to eastern North America. As its common name implies, swamp rosemallow likes to have its feet wet or at least consistently moist. With ample water and full to part sun, this plant will grow up to 7 ft tall and 5 ft wide, putting out multiple stems topped with large flowers from mid-summer to early fall. The flowers come in both pink and white. Each flower blooms for about 24 hours, but each plant has multiple blooms with staggered opening times, giving you a long blooming period overall. These flowers are visited by many insects, including a specialized bee species called the hibiscus turret bee, plus hummingbirds.

Obedient Plant (Physostegia virginiana)

This late summer/early fall bloomer comes in several colors from white to pink to pale purple. Obedient plant is ideal for sunny, damp to occasionally wet sites. Forming 3-4 ft tall clumps of flowers, obedient plant spreads and creates new clumps relatively quickly and easily.

Mist Flower (Conoclinium coelestinum)

Blooming concurrently, mist flower’s corymb of bright blue-purple flowers pairs well with the spikes of pink obedient plant flowers. Mist flower has such a striking color that it looks good paired with basically anything. Like the other plants on this list, mist flower is a rapidly growing, clump-forming plant that can spread via rhizomes and seeds. It does best in damp to wet sites with ample sun and is well-liked by pollinators, too.

Fall Yellows (and Some Orange)

Goldenrods (Solidago sp.)

Goldenrods are the pollen and nectar powerhouses of fall. Starting as early as late August, if you see a yellow flower in the landscape, there’s a good chance it is a species of goldenrod. With many species of goldenrod native to southeastern Pennsylvania, there is a well-suited goldenrod for just about any growing condition (perhaps with the exception of wet, full shade). Goldenrods are insect-pollinated and therefore do not contribute to seasonal allergies like other wind-pollinated flowers. Instead, they are a vital resource for the many bees, butterflies, moths, and other insects that need to store up pollen for the winter or, in the case of Monarch butterflies, fuel their migration to Mexico. With their many tiny yellow flowers, pollinated goldenrods produce an abundance of seeds, allowing them to spread wide and far. You may not even need to buy goldenrods to plant in your garden; there’s a good chance they will show up on their own. All they may need is your permission.

Jewelweed (Impatiens capensis)

Jewelweed most commonly comes in orange, but it also has a pale yellow form. This herbaceous filler is often found along streambanks and in moist canopy gaps within forests. Jewelweed’s other common name, “touch-me-not,” references the explosiveness of its seed pods upon even the slightest contact. This bursting characteristic is key to the species’ ability to spread.

Greens

Sensitive Fern (Onoclea sensibilis)

Calling a plant with “sensitive” in its common name an aggressive spreader may seem like an oxymoron, but trust me, sensitive fern is tenacious. It is aggressive enough that, in good conditions, it can even outcompete the commonly planted, invasive ornamental Japanese pachysandra. The reason this fern has earned the name “sensitive” is that its vegetative fronds die back at the first sign of frost, leaving behind only the fertile fronds. But come the next spring, sensitive fern re-sprouts and goes right back to vying for space. As sensitive fern spreads, it creates valuable ground cover for small mammals like chipmunks looking to pass undetected by foxes, hawks, and owls. Ferns are well-shaped for this function, with space for moving in between fronds at ground level, while providing dense leaf cover above as the fronds widen and arch to collect light.

River/Sea/Wild/Wood Oats (Chasmanthium latifolium)

This grass has many names, but one thing all of them agree on is the notability of its oat-like seeds. In my eyes, these seed heads look like they have been folded out of paper using advanced origami techniques. Dangling from their stalks, the seed heads sway in the breeze like paper lanterns strung up for a party. When they first emerge in the spring, they are green but eventually shift to light brown as they mature, and sometimes even become purple in the fall. Of course, all of these seeds are a good wildlife food source and contribute significantly to wild oats’ successful spread. Wild oats is a fairly short, clump-forming grass, typically only reaching about 2-3 ft tall, although there are instances of it growing up to 5 ft tall. This grass prefers shadier sites and can handle a wide range of soils, but typically likes wetter conditions. Bonus: wild oats are host to northern pearly-eye caterpillars and the caterpillars of several species of skipper.

Big Bluestem (Andropogon gerardii) and Indian Grass (Sorghastrum elliottii)

Check out Heritage Conservancy’s Jackson Pond Nature Preserve in Buckingham Township to see these two tall native grasses thriving, along with other plants on this list like mistflower and goldenrods. Warm-season clump-forming grasses like these two (and the wild oats above) create valuable habitat for small mammals and grassland birds. By forming clumps, these grasses leave little passageways for small critters to travel through and build nests in, providing protection from predators. Both grasses need full sun and can handle dry conditions, with big bluestem also adaptable to wetter sites. Be prepared for these grasses to grow upwards of 6-8 ft tall.

Sprawling Vines

Virginia Creeper (Parthenocissus quinquefolia)

Virginia creeper’s major contributions to gardens are its beautiful red fall color and its ability to feed wildlife, including the Virginia creeper sphinx moth (which is quite striking for a moth, worth looking up). This vine is not constrained to climbing up trees; it can also spread along the ground. Be careful to keep it away from buildings and any painted surfaces you don’t want it to latch onto, as the tendrils it climbs with can leave marks.

Trumpet Vine (Campsis radicans)

One look at trumpet vine and it’s clear that this plant has evolved to attract the eyes of our native ruby-throated hummingbird. Large, red, tubular flowers full of nectar will almost certainly grab their attention if you want to bring hummingbirds to your yard without having to constantly refill a feeder. However, trumpet vine is also almost guaranteed to take over any place you plant it, so be judicious about its placement. While the pollinated flowers produce many seeds, trumpet vine’s most effective tool for taking up space is its ability to spread by suckers and underground runners. Use this vine in sunny places for the best flower production, and in areas where its edges can be mowed or cut back to contain its spread if needed.

Hog-Peanut (Amphicarpaea bracteata)

Hog-peanut may be a vine with leaves of three, but it is not poison ivy, nor does it share any of that plant’s rash-causing oils. You can tell the difference between these two vines by hog-peanut’s small and delicate appearance. Hog-peanut will never have the red, shiny sheen or toothy leaf margin that poison ivy leaves sometimes have. This hog-peanut vine is a legume, and like other legumes, it fixes nitrogen as it grows. Interestingly, hog-peanut has two types of flowers that each follow different reproductive strategies and produce different kinds of seeds. The showy pea-like white-purple flowers are cross-pollinated and produce a seed pod that bursts when ripe. Meanwhile, lower on the plant, nondescript flowers that never even open are self-fertilized and produce an underground seed, similar to a traditional peanut. Both types of seed are edible if you are inclined to experiment with foraging.

Closing Thoughts

To be clear, basically any native herbaceous plant that finds itself in its optimal growing conditions without competition can rapidly grow, thrive, and spread. This list simply highlights a few garden-worthy species that have a greater propensity to spread.

These filler plants do much more than just take up space. Get so much more out of your garden by choosing native plants whose inter-species relationships are the foundation of our local ecology. Happy gardening!

For more information about any of these species, check out websites like the NC State Extension Gardener Plant Toolbox, Missouri Botanical Garden, Morton Arboretum, and US Forest Service. While many of these organizations are located in the Midwest with a slightly different array of native species, there are many species overlaps between the Northeast and the Midwest. You can double-check which plants are native to your county by checking the North American Plant Atlas’s US County-Level Species Maps. All you need is the scientific name of the plant.

Thanks for reading.

Katie Toner, Conservation Easement Steward