ONE GARDENER TO ANOTHER: Overwintering chrysanthemums for spring planting
Published 7:00 am Monday, November 22, 2021
The fall color this year is extraordinary. I have been traveling back and forth to central and south Alabama, and the normally ho-hum drive is now full of vibrant color. I have to be careful to keep my eyes on the road instead of admiring the passing landscape.
Arriving home, I am treated to the reds, oranges and yellows of my trees and shrubs, as well as the plethora of blooms covering the chrysanthemums that I planted earlier this year and the potted ones that are lining my front steps.
They are just about at the end of their bloom time, and it saddens me to see so many containers of spent chrysanthemums being thrown away. Commonly called mums, these brightly hued shrubs are actually perennials, meaning that they can be planted in the ground to enjoy year after year.
The best time to plant mums is in the spring. While they are producing buds in summer and in bloom during the fall months, they are putting all of their energy into producing flowers, which means they are not putting any energy into establishing roots. Mums can be planted when purchased in early fall, however, they may or may not be able to establish roots before the frost arrives.
Fortunately, whether you decide to plant them in spring or keep them in their containers for front porch decorating next fall, overwintering them is fairly easy if you follow a few basic tips to make that happen.
First, make sure that you buy mums that are of the hearty variety. Mums sold by florists are not generally winter hardy. They are grown for their unique blooms, form or size and are simply ornamental. Purchase mums with buds that have not opened yet for a longer bloom time. Water potted mums frequently, as putting out an abundance of blooms makes for a thirsty plant.
You can overwinter chrysanthemums in pots by first cutting the plant back after it is done blooming, leaving between 3 to 5 inches of stem. Water the plant well, and cover with mulch. Mums can be overwintered in a cool, dark basement or cold closet. They key here is to keep them in a cool climate, between 32 to 50 degrees Fahrenheit and in a dark area. Keep the soil slightly moist during the winter.
Mums can be overwintered in an unheated garage; however, garage temperatures can fluctuate along with the outdoor temperatures and drop below the ideal range. Although mums planted in the ground can withstand temperatures down to 20 degrees with proper mulching, potted plants lack the insulation of the ground, so when overwintering in a garage, additional insulation, such as a burlap wrap, will be necessary.
Gradually introduce the plant to light before bringing it back outside, after the threat of frost has passed. If you plan to plant your mum, ensure its success by follow a few simple care instructions.
Plant mums in a sunny spot that offers some protection when the winter winds return. Mums need to be planted in well-drained soil. This is particularly important, because mums will die because of ice that will form around its roots in soil that holds water.
The following winter, once in the ground and after a few frosts, the leaves of mums will turn brown. This is the time to cut back its foliage to 3 to 4 inches above the ground. Do not cut back to the ground as new stems will grow from the old stems. Cover the plant with a thick layer of mulch after the first frost to help insulate the plant and prevent heaving.
Heaving is the process of the ground swelling and settling as the soil freezes and defrosts. When not properly mulched, soil temperatures will fluctuate and roots can be heaved out of the ground leaving them unprotected and susceptible to cold damage. Remove mulch from over the plant in spring after the last frost.
Both potted and planted chrysanthemums benefit from pinching back stems in early to mid-summer o promote bushier plants and prevent an early bloom, which will shorten fall color considerably. To pinch back, remove the top two inches of the plant and up to half the size, leaving at least 6 sets of leaves on the stem. This can be done a few times during the summer, depending on growth rate. Stop pinching in late June allowing buds to form for fall flowers.
Mums are a persnickety perennial, but with proper care, they can add beautiful color to your fall garden for years to come. Until next week, happy gardening.
— Irland, a member of the Limestone County Master Gardeners, can be reached at kippirland@hotmail.com. Visit https://mg.aces.edu/limestone for more information on the Limestone County Master Gardeners.