Ask Mr. Smarty Plants

You have quite a challenging site, but not an impossible one in which to grow native plants. Although having such steep slope and shade and dry soils does limit the number of potenital plants, especially when limited to low ground covers. Perhaps you will consider some of the small shrubs listed below that are a little taller than ground-hugging. A planting list that includes several different types of plants would help in this site as well.

The first place to go to find a list of potential groundcovers is our Native Plant Database. Use the Combination Search feature instead of Recommended Species. This will provide a bigger selection with much more choice to narrow down. The volunteers and staff at the Wildflower Center who maintain the database have partners in different regions to help with these recommended species lists based on what is easy to access in local nurseries.
Under Combination Search, select the following categories: PA, Habit – Herb (for herbaceous), Duration – Perennial, Light Requirement – Shade, Soil Moisture – Dry, and Size Characteristics – 0-3 ft. I wouldn't suggest narrowing down this search further by indicating, blooming time and leaf characteristics or else there won't be any plants to consider. 

Follow each plant link to our webpage for that plant to learn its growing conditions, bloom time, etc. At the bottom of each plant webpage, under Additional Resources, there is a link to the USDA webpage for that plant. Take a look there for more specific details about suitability before you put them on your final planting list. Think about including plants that have interest during a variety of seasons and that have more than one attractive feature (flower, fruit, foliage, bark, etc.) so you can get more benefits out of your plants.

Here are the lowest ground covers to consider (0-1 foot tall):

Potentilla simplex (common cinquefoil), a low spreading plant to 1 ft tall with prostrate stems. Five-petaled, yellow flowers and leaves arise from runners that are up to 20 inches long. Tolerant of dry, rough, shady conditions.

Lycopodium digitatum (fan clubmoss) a low growing, non-flowering evergreen moss that is ideal for well-drained eastern woodland sites. Once established it spreads by horizontal stems on the surface of the soil. Prefers dry, shady conditions and will grow in poor soils.  

Parthenocissus vitacea (Hiedra creeper),  a low growing  vine tolerant of a wide variety of conditions from dry to moist and sun to shade. There is additional information on Hiedra creeper on the Wikipedia website. 

Low groundcover (0-1 foot tall) suggestions didn’t offer very many suggestions, so by expanding the height to 3 feet some low shrubs can be included.

Arctostaphylos uva-ursi (kinnikinnick) is a low, trailing evergreen shrub that grows to 1 foot in height but will spread up to 15 feet. It is well suited to rocky, dry, sandy hills and mountainous regions with poor, acidic soil conditions in the shade. The mealy fruit is favored by birds and wildlife.

Diervilla lonicera (Northern bush honeysuckle) is a small shrub to 3 ft. Yellow bell-shaped flowers appear during the summer. Tolerant of dry woods and shade. Suckers freely forming broad thickets with age but may be short-lived.

Gaylussacia baccata (black huckleberry) is a much-branched, colony-forming shrub to 2 feet tall. Purplish-black edible berries follow white, tubular flowers. A valuable plant for wildlife. Tolerant of dry, rocky, acid soils. A good ground cover for thin, rocky woods.

Hypericum prolificum (shrubby St. Johnswort) is a deciduous shrub to 3 ft that is moisture and soil pH adaptive. It grows well on dry, rocky slopes.

Symphoricarpos orbiculatus (coralberry) is a small mounding shrub that can grow to 4-6 feet talk. Inconspicuous greenish-white flowers lead to showy coral-pink berries in the fall. Coralberry can form extensive colonies and spreads by rooting at the stem nodes when they touch the soil. Tolerant of well-drained clay soils in dry shaded sites.

Vaccinium angustifolium (late lowbush blueberry) is a low straggling shrub only growing 6 inches tall.  Each plant spreads over 2 feet. The berries are prized by wildlife and humans alike.  Tolerant of acidic, dry, shaded sites. Maroon foliage in the fall.

Marc Radell, PSU Montgomery County Master Gardener has posted an article about Native Groundcovers on the Penn State Extension website and has some additional suggestions for dry shade conditions: For those tough areas, try Pennsylvania sedge (Carex pensylvanica), alumroot (Heuchera americana), white wood aster (Eurybia divaricata), lowbush blueberry (Vaccinium angustifolium), or American bittersweet (Celastrus scandens). I have all of these growing in relatively dry shade and they do fine. The alumroot and bittersweet do not spread as vigorously as they do when they get more moisture, but nothing seems to stop white wood aster with its attractive, heart-shaped leaves. There are many amazing cultivars of alumroot these days, and the colored foliage is a great way to brighten shady areas. In addition to delicious edible fruit, lowbush blueberries offer brilliant Fall foliage and interesting bark. I’ve also heard great things about the performance of two evergreen Dryopteris ferns in these conditions: shield fern (Dryopteris carthusiana) and wood fern (Dryopteris cristata).  I plan to try them under some spruce trees next year.