Regional Gardening Reports :: National Gardening Association

In the Garden:
Pacific Northwest
August, 2009
Regional Report

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I don't think the fall garden is complete without at least one chrysanthemum!

Fabulous Fall Mums

As the days of summer grow shorter and cooler, fall chrysanthemums burst into bloom, offering a grand finale to the garden year and a glorious complement to the vivid foliage of fall. I plant them anywhere I can for a spectacular splash of color. If there are no bare spots in the garden beds, I pop them into containers to line my front porch.

Color and Size
Mums are available in an exceptional array of colors, from white and yellow to creamy pastels and brilliant deep gold. You'll find soft pinks and lavenders, bright pinks and purples, dark reds, and bronze tones. Some lavender, bronze, and yellow mums have two-toned color patterns.

Plants range in size and shape from low, tight mounds to multi-branched, shrubby, 3-foot-tall and wide garden centerpieces. Those with a mounded or pincushion habit are usually no more than 15 inches tall. They're well suited for borders and smaller garden beds because they won't topple over or require staking as taller mums sometimes do.

The flowers of mums also come in many shapes and sizes, from tiny, tight buttons to daisies to long, curling spiders. My experience has been that the decorative flower types that bear many petals and are flat or slightly crested in the center are the most durable and retain their color better in the garden.

Garden mums are photoperiodic, meaning they bloom in response to shorter days. A night length of 12 hours triggers bud formation. Cooler night temperatures also encourage blooming. September through November is when mums are in their glory, but the flowering season actually begins in late summer and continues until a heavy frost.

Individual flowers on the plants can last from three to six weeks. High temperatures or drought can shorten the flowering period. Most garden mums can withstand several light frosts, but those with white flowers often show damage with just one frost. For this reason I usually plant the colors I associate with fall -- bronze, yellow, dark red, and deep maroon.

Getting Started
A stunning display of blooms is practically guaranteed if you plant mums in the fall. All you have to do is pop them into the ground and remember to water them during dry spells. I set young plants 18 to 24 inches apart to give them enough room to grow freely into a mound, but you can plant them more closely in masses for greater impact.

Mums are shallow-rooted and like well-drained yet moist soil that is slightly acid. If their feet are wet, growth and flowering will suffer, and plants may die. Dig in some organic matter, such as peat moss, aged manure, or compost for good moisture retention in fast-draining soils.

Ongoing Care
Mums should be fed monthly from spring through summer to encourage vigorous growth. I use a liquid 20-20-20 formulation, but they respond just as well to a granular time-release, all-purpose garden fertilizer scratched into the soil in the spring.

Mums must be pinched back during the spring and summer to encourage lateral branching and sturdy, compact growth. Unpinched mums will bloom but the plants will grow more open and develop fewer flowers.

I begin pinching mine in spring as soon as new shoots are 3 to 4 inches long. To pinch mums, grasp the growing tip and the first set of leaves on each shoot between your thumb and forefinger and nip them off, removing about 1/2 to 1 inch of stem. The plant will look neater if you pinch above a node, but this is not absolutely necessary. Pinched-back plants will push out new stems from these nodes.

Pinch again when the stems reach 3 to 4 inches long. The exact date for the last round of pinching depends upon your climate and the type of mums you are growing, but I make my last pinch in mid-August.

A few weeks after the last pinch, mums will begin to develop flower buds. If you want fewer but larger flowers, pinch out all but the center flower bud; if you want lots of flowers and don't care about the size, allow all of the buds to remain.

Favorite Mums
My favorite all-around red mum is 'Minnruby'. Its ruby red flowers are gorgeous when fresh, although they fade as they age.

Among the best performing white cultivars are 'Encore', an ivory white decorative, and 'Illusion', a prolific and showy pincushion daisy shape with dainty, white, long, tubular flowers.

'Naomi' is a daisy with spoon-tipped, tubular petals that are lavender on the outside and silvery pink on the inside, with a light green central eye.

One of the most popular garden mums is the dark lavender decorative called 'Debonair', which has very formal flowers on a strong plant with dark green foliage. 'Autumn Fire', a burnt orange selection, is another standby in the fall garden.

Reviving Older Clumps
You can count on three to four years of flowers before a mum plant needs renovation. To revitalize a tired clump, divide it in spring when new shoots appear by digging out the clump, slicing it in half with a sharp spade, and replanting the new clumps.

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