Diggin' In: Perennials take root in fine fall conditions

October 20,  2014

Fall is a prime time to put in new perennials ó trees and shrubs, too ó because winter allows roots to establish before hot, dry weather arrives again.

Horticulturists Bruce Peachee and Grace Chapman agree fall is the best planting time.

"In the fall, air temperatures are cooling while the soil retains some of its summer warmth," says Peachee, horticulture curator at the Virginia Living Museum in Newport News, Va. Each fall, the museum sponsors a plant sale for gardeners who want to expand native species in their perennial gardens for the benefit of bees, birds and butterflies.

"Rain has a better chance of soaking into the ground, rather than evaporating, so the soil tends to have more moisture in it. These are ideal conditions for plants to recover from transplant shock. The cooler air temperatures mean that the plants lose less water though their leaves and the warm, moist soil allows their roots to rapidly recover, grow and spread. Mild temperatures can last well into November here, giving new plants plenty of time to get settled, so that when spring comes they will grow quickly and be well prepared to tolerate the heat and drought to follow."

Fall is their preferred time for planting perennials and woodies, says Chapman, director of horticulture at Lewis Ginter Botanical Garden in Richmond, Va. It, too, has a fall plant sale.

"Itís all about their roots," she says.

"They can even grow all winter if the weather is mild. With a strong and healthy root system, plants are ready to take off growing quickly in the spring and will perform better through our harsh summers and in times of drought."

Many native perennials benefit insects like butterflies and bees, even birds. Here are some beneficial native species you can plant this fall:

New England Aster (Symphyotrichum novae-angliae)

Blooms July-October with lots of 1-inch violet daisies with golden clusters.

Grows 2-4 feet tall. Likes sun and average/wet, well-drained soil.

To prevent drooping, stake or cut back before buds form to get shorter bushier plants.

Benefits late-season butterflies and bees.

Cold hardy zones 4-9.

Blue lobelia (Lobelia siphilitica)

Blooms July-Sept with spikes of blue tubular flowers.

Grows 2-4 feet tall. Likes sun-part shade and average, well-drained soil.

Bottom leaves need winter sunlight; do not cover with mulch; reseeds readily on wet ground.

Benefits hummingbirds and butterflies.

Cold hardy zones 4-9.

Butterflyweed (Asclepias tuberosa)

Blooms June-September with flat-topped clusters of bright orange.

Grows 1-3 feet tall. Likes sun-part shade and average-poor/well drained-dry soil.

Drought tolerant; doesnít transplant well; comes up late and dies back early, especially when young; mark location so you donít disturb or lose it. Deer resistant.

Benefits butterflies, hosts monarchs.

Cold hardy zones 3-9.

Tennessee coneflower (Echinacea tenesseeinsis)

Blooms June-August with slightly upturned purple petals around a coppery-orange cone

Grows 1-2 feet tall. Likes light sun-part shade and average/dry-moist, well-drained soil.

Resembles purple coneflower but slightly smaller with upturned petals and a less vigorous habit. Deer resistant. Rare plant.

Benefits birds and butterflies.

Cold hardy zones 3-9.

Appalachian mountain mint (Pycnanthemum flexuosum)

Blooms summer with silvery white, globular flowers; fall foliage takes on red tinge.

Grows 2-3 feet tall. Likes full-part sun with average soil.

Stabilizes soil to reduce erosion; larval host plant for grey hairstreak butterfly; deer resistant.

Cold hardy zones 4-9.

Bluestem goldenrod (Solidago caesia)

Blooms August-October with heart-shaped, dark green leaves topped by dense plume-like panicles of bright yellow.

Grows 1-3 feet tall. Likes full sun-part shade. Drought tolerant.

Good cut flower.

Important nectar and pollen source for pollinators.

Cold hardy zones 2-9.



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