The last hurrah — brilliant colors of fall

By Lynette L. Walther | Oct 15, 2020
Photo by: Lynette L. Walther Coloring up chilly gardens are ornamental cabbages and garden center mums alongside trimmed daylily plants. Neither the cabbages nor these mums will perennialize in gardens here.

The turning of the leaves is a botanical process of trees and shrubs getting ready for the coming season of cold. As daylight time shortens, leaves prepare for winter and stop making chlorophyll. Once this happens, the green color starts to fade and the reds, oranges and yellows present in the foliage become visible.

One tree, the ash tree, displays fall color that is an indicator of what the summer has been like. A wet summer will result in yellow fall foliage. As us gardeners know all too well, this past summer was very dry. Accordingly, ash trees have responded with purple-burgundy fall foliage. They are so handsome, no matter the conditions.

Those who have swapped out their invasive burning bush (Euonymus alatus) with blueberry bushes, bear berry (indigenous kinnickinnick) or low-growing sumac (Rhus aromatica 'Gro-Low') for example, are still enjoying the brilliant fall reds in the landscape with an impressive fashion show of color.

In perennial beds, we’ve trimmed back just about everything in preparation for winter. Ornamental cabbages are good additions to the resulting bare spots in the garden. They add brilliant pops of color for the season.

Coming into their own now are hardy garden mums, like the Sheffield pink. Unlike those showy pots of garden center mums that grace many front porches and do not survive a winter to bloom again, garden mums (Chrysanthemum spp.) are herbaceous perennials in the daisy family that bloom now and return reliably each year.

By pinching back those hardy mums in mid-summer, we delay bloom time so it occurs now to coincide with the fall foliage displays, as everything else has gone by. That is just one bonus of growing hardy chrysanthemums.

Growing hardy mums

Fertile, moist, well-drained soil and full sun are requisites for success with hardy mums. Poor drainage could result in rot. Plant divisions in spring, and then around the Fourth of July, pinch plants back by about a third.

Fertilized plants will be more productive come fall. A time-release fertilizer is a convenient choice. Mums treated this way will produce thick mounds of foliage and flowers. Throughout spring and summer, these mums provide mounds of deep green foliage, making them an attractive foil for other blooming perennials. Water well throughout the summer when rainfall is not adequate.

Cut the plants down to about six inches high after blooms fade. You can cover plants with a dry mulch to protect the roots over winter, but I never found this to be necessary in my garden. Every two to three years, lift and divide established plants.

Propagating hardy mums

One of the easiest ways to produce garden mums is by rooting stem cuttings. Start with a six-inch stem from a healthy mum plant. Cut the bottom of the stem about one-half inch below the lowest leaf node. Pull off the leaves from the lower half of the cutting, leaving at least four leaves on cutting.

Bury the bare portion of the cutting in moist perlite, with one or two leaf nodes under the planting medium. Place cuttings in a warm room in bright, indirect light. Keep the perlite slightly moist at all times while avoiding overwatering. Once the cutting has rooted, transplant it into a container with potting mix. It should be ready to plant into the garden in a month to six weeks.

Common pests and diseases

Mums are quite easy to grow, rarely showing signs of disease or insect damage. However aphids, thrips and spider mites can be problematic. Look for leaf and/or stem damage, webbing on the plants and visible insects. Common diseases that can impact hardy mums include botrytis, leaf spots, rust, powdery mildew, stem and root rots, verticillium wilt, aster yellows and viruses.

If your plant has visible damage or seems to be failing to thrive, a disease might be the culprit. While spotting of leaves and powdery mildew are rarely fatal, plants with other diseases should be removed and destroyed. Do not add diseased plants to compost piles.

Hardy mum varieties

Horticulturalists generally categorize the many varieties of garden mums by flower shape: anemone, one or more rows of petals with a cushion-like center; pompom, has a globular shape; regular incurve, where the petals curve, sphere forms; single or daisy, are daisy-like; spider, which are long, curled petals that droop with spider-like appearance; and shorter, mounding varieties of mums, generally grouped as "cushion" mums.

To obtain the exceptional varieties or exhibition mums, start from seed, order from a nursery or specialty mail-order company.

Lynette L. Walther is the GardenComm Gold medal winner for writing and a five-time recipient of the GardenComm Silver Medal of Achievement and the National Garden Bureau’s Exemplary Journalism Award. Her gardens are in Camden.

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