9 Fabulous Viburnums for Your Allegheny County, PA Butterfly Garden

| Genus Spotlights

Viburnums are a host plant for four species of butterflies including the Holly Blue (Celastrina argiolus), Spring Azure (Celastrina ladon), Henry’s elfin (Incisalia henrici) and the Baltimore checkerspot (Euphydryas phaeton). In the fall, a lot of these viburnums have attractive foliage and the drupes (fruit) provide food for birds. These shrubs, which provide taller structure, can be a vital part of your butterfly garden in Allegheny County. The genus name, Viburnum, derives from the Latin word for “obscure.” All of the species discussed in this post are perennials and are shrubs, though some can be small trees.

General Information about Native Plant and Pollinator Gardens

When planting a native plant and pollinator garden in Allegheny County, PA, you need to ensure that you have a selection of plants that attract other butterflies at different time of the year. Besides viburnums, other host plants that attract other butterflies and pollinators should be considered. These could include pawpaw (Asimina triloba) for zebra swallowtail, wild cherry (Prunus serotina) for eastern tiger swallowtails, and trumpet creeper (Campsis radicans) for hummingbirds.

In addition to the plants, you need to provide a source of water such as a birdbath or water feature, shelter for animals, and nesting locations for birds. Be sure to include plants of different heights for perching. Resources you can use for more information on butterfly gardening in Allegheny County include the Penn State Master Gardeners of Allegheny County, Wild Ones Western Pennsylvania Chapter, Audubon Society of Western Pennsylvania, Xerces Society, and Phipps Conservatory and Botanical Garden.

Location of Allegheny County, Pennsylvania

Allegheny County in red on a Pennsylvania map.
Pennsylvania map with Allegheny County in red — David Benbennick, Public domain, via Wikimedia Commons

Allegheny County is located in southwestern Pennsylvania. Pittsburgh is the largest city in the county.

USDA Plant Hardiness Zones in Allegheny County, Pennsylvania

2023 USDA Plant Hardiness map of Allegheny County, PA.
2023 Allegheny County, PA USDA Plant Hardiness Map — USDA Public Domain

Allegheny County is located mostly within plant hardiness zone 6b. Adjacent to the Monongahela and Ohio Rivers is zone 7a. When selecting plants in Allegheny County, you will want to get those that can handle temperatures as cold as -50F.

Butterflies in Allegheny County, Pennsylvania that are hosted by Viburnums (Viburnum spp.)

Holly blue on a twig showing upperside of wings.
Holly Blue (Celastrina argiolus) — Bj.schoenmakers, CC0, via Wikimedia Commons
Spring azure with wings folded on a leaf.
Spring Azure (Celastrina ladon) — ALAN SCHMIERER, CC0, via Wikimedia Commons
Orange and black Baltimore Checkerspot with wings outspread on vegetation.
Baltimore Checkerspot with Wings Outspread — D. Gordon E. Robertson, CC BY-SA 3.0, via Wikimedia Commons
Henry's Elfin (Incisalia henrici) on the ground.
Henry’s Elfin — Callophrys henrici (Grote & Robinson, 1867) observed in United States of America by izzykracken (licensed under CC0 1.0).

Henry’s Elfin (Callophrys henrici)

The Henry’s elfin has a dark brown upperside and an underside that is two toned brown. As an adult it is a small butterfly with a wingspan of 0.8 in (2.0 cm) to 1.0 (2.5 cm).

The light green eggs are laid on leaves or flower buds of the host plant. The larva when hatched range from greenish-yellow to red-brown in color. The pupas are orange brown in color and this species has one brood a year.

Holly Blue (Celastrina argiolus)

The holly blue has a silvery blue color with ivory dots on the upperside and a silvery-white underside. Adults have a wingspan of 1.4 in (3.6 cm) to 3.5 in (8.9 cm).

The whitish eggs are laid on the leaves of the host plant and they have green or brown larvae. This species can have up to three broods throughout the growing season.

Spring Azure (Celastrina ladon)

The Spring Azure is a silvery metallic blue on the upperside and has a silvery underside. The females, unlike the males, have a black margin on the wings. A fully grown adult has a wingspan of 0.87 in (2.2 cm) to 1.38 in (3.5 cm).

The whitish eggs are laid on the flower buds of host plants. Larvae are green colored with accents of brown. The chrysalis overwinters and there can be several broods a year with more in the south and less in the north.

Baltimore Checkerspot (Euphydryas phaeton)

The Baltimore Checkerspot is a speckled white, orange and black butterfly. This butterfly is found in the eastern United States and southern Canada from the mid-west and east. Adults have a wingspan of 1.6 in (4.1 cm) to 2.5 in (6.4 cm).

The eggs of this species are yellow and become a reddish-tan color with age (wildadirondacks.org). The caterpillars are black with orange stripes (Pyle 1981). There is one brood that flies from May to July. This butterfly is so named because the color resembles the crest of Lord Baltimore (Pyle 1981).

List of Viburnums that are Native or Nearly Native in Allegheny County, Pennsylvania

1. Maple-leaf Viburnum (Viburnum acerifolium), a Viburnum for Dry to Moist Well-drained Soils

When planted in a butterfly garden, this species does best in places that are shaded, but can handle some sun if dappled. During establishment it needs to be watered frequently. Pruning can be done after flowering to promote bushier growth.

Suitable herbaceous companion plants include New England Aster (Symphyotrichum novae-angliae), black-eyed susan (Rudbeckia hirta), wild indigo (Baptisia australis). Oakleaf hydrangea (Hydrangea quercifolia) and eastern redbud (Cercis canadensis) are suitable woody plants that match the height. All of the these species listed compliment the foliage of this plant in the autumn.

White flowers of maple-leaf viburnum (Viburnum acerifolium) in a wooded area.
Flowers of Maple-leaf Viburnum — Viburnum acerifolium L. observed in United States of America by Craig Martin (licensed under CC0 1.0).

Facts about Maple-leaf Viburnum

  • Native to Pennsylvania: Yes (Kartesz 2015)
  • Native to Allegheny County: Yes
  • Natural Habitat: Rich forests, woodlands and woodland thickets that are rocky and have medium to dry soils.
  • Height: 3 ft (0.9 m) to 6 ft (1.8 m)
  • Flower Color: cream to white
  • Flowering Period: June
  • USDA Hardiness Zone: 3-8

Gardening with Maple-leaf Viburnum

In your Allegheny County, PA butterfly garden this plant requires part-shade or dappled sunlight and dry to moist soils that are well-drained. This plant can handle full sun conditions in a garden, but it does best in shaded conditions (Wyman 1959).

2. Southern Arrow-wood (Viburnum dentatum), a Viburnum for Moist to Medium Well-drained Soils

Southern arrow-wood can handle both full sun to partial-shade, however, full sun is needed for the best fruit production. Planting should occur in the early spring or autumn to ensure that the plants have time to establish roots before the growing season. Plants should have a consistent amount of water during establishment. Though, once established they can handle drier soils, if needed.

Suitable herbaceous companion plants include butterfly weed (Asclepias tuberosa), little bluestem (Schizachyrium scoparium), wild geranium (Geranium maculatum). Some companion shrubs are New Jersey tea (Ceanothus americanus) and spicebush (Lindera benzion). Some of these plants are also hosts to other butterflies.

Cream-colored flowers of southern arrow-wood (Viburnum dentatum).
Flowers of Southern Arrow-wood — Viburnum dentatum L. observed in United States of America by aberkov (licensed under CC BY 4.0).

Facts about Southern Arrow-wood

Viburnum dentatum var. dentatum in Pennsylvania

  • Native to Pennsylvania: Yes, mainly southeastern PA and Greene County in southwest (Kartesz 2015)
  • Native to Allegheny County: No
  • Natural Habitat: Rich forests, woodlands, floodplains, and wetlands
  • Height: 5 ft (1.5 m) to 15 ft (4.6 m)
  • Flower Color: cream to white
  • Flowering Period: March to June
  • USDA Hardiness Zone: 2-8

Gardening with Southern Arrow-wood

In your Allegheny County, PA butterfly garden, this plant requires full sun to part shade and moist well-drained soils. In a garden situation it can handle drier soils (Flemer 1984). This viburnum has brilliant color in the fall, which gives added value to your garden.

3. Hobblebush (Viburnum lantanoides), a Viburnum for Moist to Wet Soils

Hobblebush can currently handle the hardiness zone of Allegheny County (except next the Monongahela River and Ohio rivers). However, in the future it experience heat-stress from climate change induced warming. It enjoys places that have partial shade and are moist to wet. Given that it is at the edge of its hardiness zone, it might be better in more shade. Planting should occur in the early spring or autumn to ensure sufficient root growth.

Some suitable herbaceous companion plants include columbine (Aquilegia canadensis), foam-flower (Tiarella cordifolia), Heuchera (Heuchera spp.), and Christmas fern (Polystichum acrostichoides). Red-osier dogwood (Cornus alba) is an excellent woody companion.

White flowers and leaves of hobblebush (Viburnum lantanoides).
Flowers of hobblebush (Viburnum lantanoides) —Wladyslaw, CC BY-SA 3.0, via Wikimedia Commons

Facts about Hobblebush

  • Native to Pennsylvania: Yes, generally throughout, except for southeast and southwest (Kartesz 2015)
  • Native to Allegheny County: No
  • Natural Habitat: Rich woods that are moist, stream banks, and swamps
  • Height: 3 ft (0.9 m) to 10 ft (3.0 m)
  • Flower Color: white to pink
  • Flowering Period: May to June
  • USDA Hardiness Zone: 3-6

Gardening with Hobblebush

In your Allegheny County, PA butterfly garden, this plant requires part shade and moist to wet well-drained soils.

4. Nanny-Berry (Viburnum lentago), a Viburnum for Medium to Moist Well-drained Soils

Nanny-Berry likes places that have full sun to partial shade and well-drained soils. Similar to the other viburnums, planting needs to occur in the early spring or autumn to ensure adequate root development. This species generally likes consistent moisture during root development.

Some suitable herbaceous companion plants, given the height of this plant include Joe-Pye Weed (Eutrochium purpureum), obedient plant (Physotegia virginiana), Virginia creeper (Parthenocissus quinquefolia), woodland phlox (Phlox divaricata), and Ironweed (Vernonia noveboracensis), if in a sunny area. Virginia creeper (Parthenocissus quinquefolia), if given a place to climb, compliments the autumn foliage of this plant.

White flowers and leaves of nanny-berry (Viburnum lentago).
Flowers of Nanny-Berry — Viburnum lentago L. observed in Canada by Andrew Macumber (licensed under CC0 1.0).

Facts about Nanny-Berry

  • Native to Pennsylvania: Yes, generally throughout, except for south-central (Kartesz 2015)
  • Native to Allegheny County: Yes
  • Natural Habitat: Rich woods that are moist, stream banks (King 1912), swamps, roadsides (Arnold Arboretum 1919), wood edges (Mohlenbrock (1954), and thickets (McCormac and Schneider 1994)
  • Height: 15 ft (4.5 m) to 18 ft (5.5 m)
  • Flower Color: white to cream
  • Flowering Period: May to June
  • USDA Hardiness Zone: 2-8

Gardening with Nanny-Berry

In your Allegheny County, PA butterfly garden, this plant requires full sun to part shade and soils that are medium to moist and well-drained.

5. Possumhaw (Viburnum nudum), a Viburnum for Medium to Wet Well-drained Soils

Possumhaw is a small to medium sized shrub that can handle medium moisture soils, but especially prefers places that are moist and well-drained. Planting should occur in the early spring or autumn to allow for root development and the soils need to have some compost or manure for nutrients.

Suitable herbaceous companions, given the preferred habitat include swamp milkweed (Asclepias incarnata), blueflag iris (Iris versicolor), and tussock sedge (Carex stricta), in very wet places. Some companion shrubs include sweet pepperbush (Clethra alnifolia), and northern bayberry (Morella pennsylvanica).

White to pinkish drupes of possumhaw (Viburnum nudum).
Fruits of Possumhaw — Viburnum nudum L. observed in United States of America by Becky (licensed under CC0 1.0).

Facts about Possumhaw

Viburnum nudum var. cassinoides and var. nudum in Pennsylvania

  • Native to Pennsylvania: Yes, throughout, except southwest (var. cassinoides), rare in southeast (var. nudum) (Kartesz 2015)
  • Native to Allegheny County: No
  • Natural Habitat: Swamps (wikipedia), seepage swamps (Belden and Derge 2003 and Sundell, et al 1999), and bogs (MacRoberts, et al 2004)
  • Height: 5 ft (1.5 m) to 15 ft (4.6 m)
  • Flower Color: white to cream
  • Flowering Period: April to June
  • USDA Hardiness Zone: 5-9

Gardening with Possumhaw

In your Allegheny County, PA butterfly garden, this plant requires full sun to partial shade and medium to wet well-drained soils.

6. Highbush-Cranberry (Viburnum opulus), a Viburnum for Medium to Moist Well-drained Soils

Highbush-cranberry is another small to medium sized shrub that likes medium to moist soils, but tends to favor the moist end of the spectrum. When planting this shrub make sure that you get the native variety (americanum) and not the European variety (opulus), which is exotic to North America. Variety americanum has stalked petiolar glands, while variety opulus has sessile petiolar glands. In time this species may experience heat stress, due to being at the upper end of its hardiness zone.

Suitable herbaceous companion plants for moist conditions include marsh marigold (Caltha palustris), cardinal flower (Lobelia cardinalis), and great blue lobelia (Lobelia siphilitica). Companion shrubs include gray dogwood (Cornus racemosa) and buttonbush (Cephalanthus occidentalis).

Flowers of highbush-cranberry (Viburnum opulus) in a sunny area.
Flowers of Highbush-Cranberry — Jason Grant, CC BY 4.0, via Wikimedia Commons

Facts about Highbush-Cranberry

Viburnum opulus var. americanum: Native and rare in Pennsylvania

Viburnum opulus var. opulus: Exotic to North America

  • Native to Pennsylvania: Yes, rare and scattered throughout (var. americanum) (Kartesz 2015)
  • Native to Allegheny County: No
  • Natural Habitat: lowland woods (Macdonald 2003), moist woods (Bird 1961), rivershores and banks (Hosie 1938), shrub swamps (Thomson 1944), gravelly calcareous places (Wiegand and Eames 1926), swamps and rarely dry woods (McVaugh 1958), and roadsides and field edges (Go Botany)
  • Height: 8 ft (2.4 m) to 16 ft (4.9 m)
  • Flower Color: yellow to white
  • Flowering Period: April to June
  • USDA Hardiness Zone: 2-7

Gardening with Highbush-Cranberry

In your Allegheny County, PA butterfly garden, this plant requires full sun to part shade and medium to moist well-drained soils. This species has two varieties, one of which, var. opulus, is exotic to North America. Variety americanum is native to North America.

7. Smooth Blackhaw (Viburnum prunifolium), a Viburnum for All Soils

Smooth blackhaw is a short to tall shrub that can handle most conditions in the garden including poor soils. However, the exposure should be in full sun to partial-shade. Also like other viburnums, it should be planted at a time when it will have time to develop roots before the warm season.

Due to its height, smooth blackhaw should generally be planted with other tall shrubs such as winterberry holly (Ilex verticillata) and sweet pepperbush (Clethra alnifolia). Suitable small trees include eastern redbud (Cercis canadensis) and witch-hazel (Hamamelis virginiana). Purple Joe-Pye weed (Eutrochium purpureum), would basically be the only herbaceous plant companion considering the height of the adjoining shrub.

White flowers of smooth blackhaw (Viburnum prunifolium) in a shaded area.
Flowers of Smooth BlackhawKrzysztof Ziarnek, Kenraiz, CC BY-SA 4.0, via Wikimedia Commons

Facts about Smooth Blackhaw

  • Native to Pennsylvania: Yes, generally throughout, except for northern counties (Kartesz 2015)
  • Native to Allegheny County: Yes
  • Natural Habitat: Open areas, upland woods, floodplains (Gaddy 2008), disturbed habitats (Clark and Bauer 2001), thickets (Fernald 1936)
  • Height: 7 ft (2.1 m) to 30 ft (9.1 m)
  • Flower Color: white
  • Flowering Period: May to June
  • USDA Hardiness Zone: 3-9

Gardening with Smooth Blackhaw

In your Allegheny County, PA butterfly garden, this plant requires full sun to part-shade and dry to moist well-drained soils. This plant can also handle poor soils, making it versatile for most gardens.

8. Downy Arrow-wood (Viburnum rafinesquianum), a Viburnum for Medium Well-drained Soils

Downy arrow-wood is a small shrub that especially relishes full sun to partial-shade in medium moisture soils. When planted, an ample amount of mulch should be used. Given the height, spotted Joe-Pye weed (Eutrochium maculatum) and purple coneflower (Echinacea purpurea) are suitable herbaceous companions. Companion shrubs include pinxter flower (Rhododendron periclymenoides) and sweetspire (Itea virginica).

White flowers of downy arrow-wood in a wooded area.
Flowers of Downy Arrow-wood — Superior National Forest, CC BY 2.0, via Wikimedia Commons

Facts about Downy Arrow-wood

  • Native to Pennsylvania: Yes, throughout, but scattered (Kartesz 2015)
  • Native to Allegheny County: Yes
  • Natural Habitat: open woodlands, rocky hillsides (Reaume 2009), rocky shorelines (Rousseau 1974), limestone savanna (Alvar) (Catling and Brownell 1995), and dry thickets (Maycock and Eahselt 1997), and low woodlands (Fernald 1942)
  • Height: 6 ft (1.8 m) to 10 ft (3 m)
  • Flower Color: white to cream
  • Flowering Period: May to June
  • USDA Hardiness Zone: 3-8

Gardening with Downy Arrow-wood

In your Allegheny County, PA butterfly garden, this plant requires full sun to part shade and dry well-drained soils. This species is noted for its bronze-purple foliage in the fall (Koller 1981).

9. Rusty Blackhaw (Viburnum rufidulum), a Viburnum for Medium to Wet Soils

Rusty blackhaw looks very similar to the smooth blackhaw (Viburnum prunifolium). However, the leaves of the rusty blackhaw have a reddish hue to them from rusty colored pubescence. Planting needs to be done in the early spring or in the autumn to allow for adequate root growth.

Suitable garden companions include eastern redbud (Cercis canadensis), black chokeberry (Aronia melanocarpa), and American beautyberry (Callicarpa americana).

White flowers of rusty blackhaw viburnum (Viburnum rufidulum).
Flowers of Rusty Blackhaw — Viburnum rufidulum Raf. observed in United States of America by alymharmon (licensed under CC0 1.0).

Facts about Rusty Blackhaw

  • Native to Pennsylvania: No (Kartesz 2015)
  • Native to Allegheny County: No
  • Natural Habitat: rocky and dry woods, woodlands (Wofford, et al 1979), glades (Steyermark 1940), limestone (Thompson, et al 2005), cedar barrens (Carr 1944), calcareous prairies (MacRoberts and MacRoberts 1996), xeric sandhills (MacRoberts and MacRoberts 1995), and disturbed habitats (Clark and Bauer 2001)
  • Height: 6 ft (1,8 m) to 20 ft (6.1 m) or up to 40 ft (12.2 m) (Arnold Arboretum 1923)
  • Flower Color: white to cream
  • Flowering Period: April to May
  • USDA Hardiness Zone: 5-9

Gardening with Rusty Blackhaw

In your Allegheny County, PA butterfly garden, this plant requires full sun to part-shade and soils that are medium to dry well-drained. This shrub has deep red foliage in the fall (Goodrich 1973).

References

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Author’s Bio: Robert Coxe is the owner of McMullen House Bed & Breakfast LLC and Silphium Design LLC (a web development firm). Robert has a graduate degree in systematic botany and ecology and is the former State Ecologist of Delaware and a former ecologist at the Western Pennsylvania Conservancy. He is also a past-president of the Pennsylvania Academy of Science. Robert has a blog about native plant and butterfly gardens at the McMullen House Bed & Breakfast Garden Shop.