Featured Native Plants

New England Asters (Symphyotrichum novae-angliae)

Doug Tallamy, University of Delaware entomologist and author, tells us that among perennial species, asters and goldenrods support the most diverse native pollinators. These two plants probably already occupy a place in your garden as they are both prolific common wildflowers found in the New England area. This month we would like to focus on New England asters (Symphyotrichum novae-angliae.)

The Asteraceae family is one of the largest flowering plant families in North America. Aster blooms appear in your garden in late summer and fall when the garden is looking tired and spent, adding a much-needed pop of vibrant color to your sunny border. More than that, they provide an essential source of late-season pollen resources for bees and butterflies and seed heads for songbirds in winter.

The colors of New England Asters vary from purple to violet to all shades of pink, but the rich purple flowers with yellow centers are the iconic harbingers of fall. Asters, left to grow to maturity, can reach 5 feet tall but can be pinched back in from early spring to mid-summer to reduce the height and encourage branching out, which increases blooms. Pinch off the first set of leaves with your fingers just before the node on the stem. It is unnecessary to prune unless you have very rich soil and the asters grow taller than your space or design allows.

If you have a shaded area that needs a pop of brightness, White Wood Asters (Aster divaricata) are an excellent, easy plant to grow from seed. Again to keep the plants tidy, you can cut them back early in the season to 12 inches.

Because asters are native to our area, they are easily spread by seed. If your aster has produced many babies the following year, it can be a great plant to swap with friends. If you have too many asters, cut some seed heads after blooming to reduce spreading. If you would like asters in other areas of your garden when the seed heads are dry, simply sprinkle the seeds in disturbed soil in the fall. In the spring, you will have a new bed of asters.

Asters are an easy native plant that thrives in all types of soil, provides food for wildlife, and is deer resistant. There is no reason not to add these garden workhorses to your landscape.

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Culver's Root (Veronicastrum virginicum)

Culver’s Root (Veronicastrum virginicum) is an impressive native perennial plant found in moist meadows and open woods throughout the eastern United States. The genus name is a combination of Veronica and the suffix astrum ("false") and refers to the plant's resemblance to the Veronicas. It is the only species of Veronicastrum in North America. The common name Culver’s Root derives from a pioneer physician of the late 17th and early 18th centuries, Doctor Culver, who advocated for medicinal uses of the roots.

The plant grows up to 4-5 feet tall and 2 feet wide. Its unbranched stems are upright and have narrowly oval, deep green leaves arranged in groups of three to seven in whorls around the stems. The arrangement of leaves is very attractive. From July to mid-August, the stems are topped by spikes of hundreds of densely clustered, small tubular white flowers that branch and create a candelabra-like look. Bloom time can be extended by deadheading the flowers as they start to fade. Butterflies, bees, and other pollinators love the flowers.

The plant performs best in full sun or light shade. In the wild, it is commonly found in wet or moist locations, but it is adaptable in the garden and does well in average or even slightly dry, well-drained soil. The stems tend to flop over and will require support without enough sun. The plant is clump-forming and looks elegant as an accent plant towards the back of a perennial border. It also looks great in a meadow or a wildflower garden. Beautiful native companion plants for Culver’s root include ironweed (Vernonia fasciculata), wild bergamot (Monarda fistulosa), black-eyed Susan (Rudbeckia hirta), and false sunflower (Heliopsis helianthoides).

Culver’s root is most easily propagated by plant division in late fall or early spring. It can also be propagated by plant cuttings taken in late spring or sown from seeds that ripen in the fall. The plant is long-lived but may take a few years to fully establish itself in a new location. It has no disease or pest problems, and the foliage is unpalatable to deer and other herbivores.

Milkweed (Asclepias spp.)

Butterfly weed (Asclepias tuberosa) with bee.

The Asclepsis genus, commonly referred to as Milkweed, includes over 70 species native to the US and over 100 native to North America. The name milkweed comes from their latex, a milky substance that is released if the cells of the plants are damaged. These are beautiful and beneficial plants that support a large number of butterflies and moths. This includes the Monarch butterfly, which depends on milkweed for reproduction. Milkweed is the only plant upon which monarch caterpillars can feed and survive. Since Monarchs are in decline, it is essential that we all grow milkweed in our gardens. Some species that do well in our region include the Butterfly Weed (Asclepias tuberosa), Common Milkweed (Asclepias syriaca), and Swap Milkweed (Asclepias incarnata). All three are readily propagated by seeds that can be sown in the fall or, after cold-stratification, in the spring.

Butterfly weed (Asclepias tuberosa), shown in the two photos to the left, has up-right stems and narrow alternate green leaves. It produces spectacular flat-topped clusters of orange flowers in late June and early July. The nectar-rich flowers provide food for butterflies and other insects. It is found from Maine to Florida in the eastern US and from South Dakota to the southern desert states in the west. The plant grows best in full sun and tolerates a range of soil conditions from moist to dry, average to lean, and acidic to neutral. At 2-3 feet tall and wide, it is relative small and can be placed towards the front in a flower bed or at the edge of a wildflower meadow. Being relatively heat and drought- tolerant, it also does well in traffic islands and other hard-to-grow places with dry and sandy soil.

Note: Butterfly weed should not be confused with the Butterfly bush (Buddleia davidii), which is non-native shrub originally from China. Because of its name, many gardeners believe that this shrub benefits our butterflies. However, while it does provide nectar to adult butterflies, it does not have any value for reproduction of new butterflies since the caterpillars cannot feed on its leaves.

Common milkweed (Asclepias syriaca) is a hardy perennial native to Canada and much of the eastern United States. Common milkweed supports more than 450 insects including flies, beetles, ants, bees, wasps, and butterflies. It is an important food source for monarch butterfly caterpillars, in particular.

It thrives in full sun and has a preference for moist soil. But it also tolerates dry conditions. The plant becomes two to six feet tall, with large gray-green leaves and pale purple-pink flowers. It is a beautiful plant. However, it is an aggressive grower and often not recommended for smaller or more formal gardens. In addition to spreading by seeds, it has underground rhizomes that allow it to spread to unwanted places. Thus, it is best planted in meadows or other areas where it has room to grow.

Common milkweed (Asclepias syriaca) with bee and Monarch butterfly.

Swamp or rose milkweed (Asclepias incarnata)

Swamp milkweed (Asclepias incarnata), also known as Rose Milkweed, prefers medium to wet garden soil and full sun or partial shade. In the wild, it is often found growing near the edges of ponds, lakes, streams, or along ditches. Compared to the common milkweed, this is a well-behaved plant that forms clumps and does not spread by rhizomes. It grows 2 to 4 feet tall and produces beautiful deep rose-pink flowers in mid- through late summer. Along with Common Milkweed, this may be the most beneficial milkweed plant for the Monarch butterfly, which feeds on its flowers and lays its eggs on the plant.

Note: While the three species of milkweed described above are highly desirable plants, a closely-related but must-remove plant is the invasive Black Swallow-wort (Cynanchum louiseae). A female Monarch will sometimes place its egg on this plant, unable to distinguish it from milkweed. Unfortunately, the leaves of Black Swallow-wort are poisonous to monarch caterpillars, and they will not survive on this plant. Thus, if you have this plant, make sure to dig it up (roots too!). Cutting or hand pulling alone will not eliminate it.

Amelanchier or Serviceberry (Amelanchier spp.)

Amelanchier canadensis in a Lexington home garden.

In addition to having exceptional spring flowers, many Amelanchiers also have stunning fall colors and an ornamental silvery gray bark, making them a multi-season delight. Some species commonly used as landscape plants in our area are:

Amelanchier canadensis, commonly called Canada serviceberry or shadbush, is a large upright suckering shrub or small tree which typically grows 15-20' tall and half as wide. In the wild, it grows in moist soil along stream banks and ponds. In cultivation, it tolerates average soil, and it does well at the edge of woodlands and in naturalized or native plant gardens.

Amelanchier arborea, the downy or shadblow serviceberry, is a small multi-stemmed tree that typically grows to 15-25’ tall in cultivation, but can reach 40’ in the wild. The common name downy describes the leaves, which can be fuzzy when they first appear in the spring. Its close relative Amelanchier laevis, commonly called Allegheny or smooth serviceberry, shares its growth habits. However, the latter is considered a better choice for gardens due to an attractive bronze leaf color in the spring and juicier, better-tasting fruit.

Amelanchier x grandiflora, or apple serviceberry, is a cross between Amelanchier arborea and Amelanchier laevis. This is a winning combination that has beautiful new growth, splendid fall color, larger flowers, and more delicious fruit. It does not grow as tall as some of the other species and does fairly well in shade.

All of these Amelanchier species provide excellent benefits to wildlife because of the nectar, pollen, and berry resources they produce. They also serve as host plants for close to 120 caterpillars, including those of many butterfly species.

The genus Amelanchier, also known as serviceberries, comprises some 20 deciduous shrubs or small trees, many of them native to the eastern United States and Canada. They are among the first to flower in the spring, making them extra lovely. Their delicate white flowers emerge in late March or early April and last five to seven days, depending on the weather. The flowers are an essential source of pollen and nectar to newly emerged bees and other insects. The flowers are followed by berries which turn red before maturing to a dark blue color in the middle of summer. The berries are edible and rival blueberries in terms of size, sweetness, and flavor. The berries can be used in jams, jellies, and pies if you can harvest them before the birds devour them. Many species of birds rely on these high-energy berries to sustain them during the breeding season.

Red-Twig Dogwood (Cornus sericea)

The bright red twigs are beautiful in any winter garden, especially when planted against a backdrop of evergreens. Though the color is best when the plant grows in full sun, it also tolerates light shade. Unlike the Florida dogwood tree (Cornus florida), which is stunning in the spring, this shrub has relatively small spring flowers. However, the flowers attract many pollinators, and birds quickly consume the berries.

For the best winter color, prune this low-maintenance shrub when the branches are more than two years old or cut the entire plant almost to the ground in early spring. Only prune about one third of the plant each year. Over-pruning can reduce the number of flowers and berries. Red-twig dogwood is a tremendous four-season plant that deserves a home in every garden. Read more at the Rhode Island Wild Plant Society or the Missouri Botanical Garden.

The common name red-twig dogwood accurately describes this garden gem. Red-twig refers to the branches that become bright red in the winter. Its botanical name, Cornus sericea, also reflects its appearance. Cornus means horned or antlered, which refers to branching habit, and sericea, which means covered with fine silk or hair, refers to the silky hair found on new young leaves. The ovate to elongated leaves are 2-5 inches long and 1-2.5 inches wide. The plant is a fast grower and, unpruned, becomes 8-10 feet tall and slightly wider.

Red-twig dogwood is native to most of the United States and is a host plant for over 117 butterfly and moth species. It also provides pollen for our native bees. In unmanaged landscapes, it is an understory shrub mostly found by streams and riverbanks. But it will perform well in most garden settings. It can also be very useful in a rain garden where it thrives in the moister soil. Birds consume the berries, and the antlered branches make good nesting sites and shelter for birds and other animals.