Ask Mr. Smarty Plants

There are a good number of short native shrubs that grow in the District of Columbia and which are both attractive and a deterrent for you to consider. The challenge will be to match the plants with your ultimate height restriction so that when the plants reach their mature height they don't require excessive pruning to keep them below the window sill level. So to find a list of potential plants, head to the Native Plant Database and select: District of Columbia, shrub, perennial, sun (or part shade if this fits your site better), moist and 1-3 feet for the search criteria.

This search for shorter (1-3 feet tall) plants resulted in two potential shrubs. 

Gaylussacia baccata (black huckleberry) and Rosa carolina (Carolina rose).

The black huckleberry forms a short shrub to 2 feet. It has small white flowers in the early summer followed by purple edible berries. The leaves turn orange and crimson in the fall before dropping. The plant is very tolerant of many soils but is happiest in acidic conditions. It is a good host for many forms of wildlife and birds.

The Carolina rose is also a short shrub growing from 1-3 feet tall. It has fragrant, single pink flowers in early summer that transform into a bright red fruit. The stems are thorny and would be a good deterrent. Although this rose is one of the most shade tolerant, it grow best in full sun. An important bee plant.

A search for taller (3-6 feet tall) shrubs produces the following:

Amelanchier stolifera (running serviceberry) and Symphoricarpos albus (common snowberry)

The running serviceberry has white blooms in the early spring. The Missouri Botanical Garden website reports the following noteworthy characteristics. Running serviceberry is a deciduous, early-flowering, stoloniferous shrub which typically suckers and spreads to form thickets. It usually grows to only 3-5' tall and features 5-petaled, showy, white flowers in drooping clusters which appear before the leaves emerge in early spring. Finely toothed, oval to almost circular, medium to dark green leaves (1-3" long) lack teeth on lower edges and change to variable shades of yellow, orange and red in autumn. Flowers give way to small, round, green berries which mature to a dark purplish-black in summer. Edible berries resemble blueberries in size and color and are often used in pies. Amelanchiers are also commonly called Juneberries.

Common snowberry grows up to 5 feet tall (and the same width). The small pinkish white flowers are quite inconspicuous during the summer but it is the snow white berries that are the most showy in the fall.