The fall garden wouldn’t be complete without a display of garden mums. These plants have a profuse number of blooms with a wide variety of flower forms and plant sizes that extend well into the fall season. Flower colors come in white, yellow, bronze, purple, red, and pink. With such a range of choices it is easy to see why mums are such a popular fall plant. When selecting your mums, make sure you have the garden variety as florist mums are not hardy enough to survive our winter weather. Even garden mums need some extra care to ensure their return each year.
Mums are a very shallow rooted plant. The crown of the plant will become bushy and full. If the plant has sufficient winter protection it will send out smaller side plants which helps make the mum plant larger with each successive growing season. After a few years you might notice that the crown of the plant will seem to thin out. This is usually a sign that the plant needs to be divided. This should be done in the spring to allow the plant to set roots and get re- established. Liberal amounts of compost, rotted manure, or organic matter should be worked into the ground, as mums grow best in a rich loamy soil. They are heavy feeders, so a spring application of a 10-10-10 fertilizer is also a good idea. It is also beneficial to provide mulch around the base of the plant which will help retain soil moisture and keep the roots cool.
Mums will provide their best show of color and blooms when planted in a sunny area. Spring planted mums should have their flower buds removed if there are any on the plant when purchased. This allows the plant to put more energy into establishing its root system. As this newly planted mum continues to grow throughout the summer months it will branch out to form a fuller plant with more blooms. It is also recommended to pinch back new and established mums early in the season. This will help ensure a bushier plant with more blooms. Pinching back should cease after the first week of July otherwise bud formation may be delayed enough to prevent sufficient flowering. Bud formation and flowering is dependant on lengthening night hours that come with the change of seasons. Thus mums should not be planted near outside night lights, as this may delay the bloom time or in some cases prevent the plant from blooming at all.
Winter protection is needed to help this plant survive. When the ground has frozen to a depth of 2 inches, a thick layer of mulch should be put over the plant. I usually do this around Thanksgiving. A 6 to 8 inch layer of clean straw, leaves or pine needles is suggested. Christmas tree branches can also be put over this mulch for added protection. Make sure the mulch isn’t removed too early in the spring as this may make the plant more susceptible to repeated frost heave which can lead to its demise. On the other hand, you don’t want to leave the mulch on too long, which can promote crown rot. A suggestion would be to start removing some of the pine branches in early April, but don’t be in a hurry to take off the other mulch until you are sure there is no further danger of a hard freeze.
Mums look great planted with tall grasses or sedum. Potted mums and coleus are also a great combination. The rich and varied hues of mum blossoms are outstanding in the fall garden.
Until next time…happy gardening.
Nina Binkley, UW Extension master gardener volunteer