Middle Tennessee's 39 counties fall into U.S. Hardiness Zone 6B, with a minimum average temperature of minus 5 degrees F. Middle Tennessee's gardens face subfreezing temperatures and hot, dry summers. The upside is a long period between the final spring and first autumn frost. Nashville, for example, seldom sees frost after mid-April or before mid-October. Carefully chosen plants and shrubs provide up to six months of garden enjoyment.
Indigo bush (Amorpha fruticosa) is a rapidly growing perennial reaching between 6 and 10 feet high and up to 15 feet wide. Belonging to the pea family, this airy shrub produces leaves and flowers along the upper one-third of its branches. The blue or purple flowers, with contrasting orange anthers, appear in 3-to-6-inch spikes between April and June. Blooming indigo bush is a striking backdrop for flowering spring bulbs. Its delicate gray-green leaves become yellow in autumn.
Plant these shrubs in moist, acidic sandy or loamy soil and full sun to part shade. They thrive along streams and in water gardens. Both bees and butterflies gather their nectar. Indigo bush self-sows readily. Remove young plants to prevent them from becoming invasive.
During June and July, oakleaf hydreangea (Hydrangea quercifolia) shrubs put on a show along the river banks and in the damp woods of Middle Tennessee. Named for their oak-like deep green leaves, these 3-to-12 foot mounding plants have flat, loose irregular clusters of white flowers rising above pale green buds. The flowers become rose-purple as they age, remaining on the plants through the winter. They are breathtaking against the hydrangea's brilliant burgundy-red fall foliage.
Plant oakleaf hydrangea, according to the Lady Bird Johnson Wildflower Center, in shade and moist, well-drained pH-neutral soil. Plants spread easily via their root systems. Cutting new canes will control the spread. Shape the shrubs by pruning them right after they flower.
Rapidly climbing virgin's bower (Clematis virginiana) vine can grow as much as 20 feet in a single season. A perennial, virgin's bower bears abundant clusters of tiny fragrant white flowers between July and September. Its deep green leaves make the flowers appear even brighter. Both butterflies and hummingbirds feed on the nectar.
Female flowers produce achenes, seeds with feathery tails like dandelion seeds, during late summer, providing even more garden interest. Requiring support, this vine will cling to other plants unless you train it to a trellis, fence or espalier. Plant it in full sun or shade. It performs best in moist rich soil. Prune the vine in early spring to encourage bushiness.
All parts of Virgin's bower are toxic. Handle it with gloves to avoid short-lived skin redness and stinging. Do not ingest it.