Summer is rapidly fading and fall is just as quickly coming upon us in the garden. A favorite fall sight in the garden is the garden mum, which blooms when many of the other annuals and perennials are winding down for the season.
Mums are photoperiodic, which means they bloom in response to day length. As short-day plants, they bloom in response to short days and long nights. A variety of sizes and colors of mums are filling local garden centers, florist centers and big box stores so there is plenty of choice when selecting some great fall color to liven up your favorite garden spot.
Many people wonder why their mums planted in the fall don’t survive Iowa winters and return come spring. The best time to plant mums is actually in the spring. Mums have a shallow fibrous root system that requires a longer period of time to establish for good growth and survival. These roots are easily damaged or destroyed by changing temperatures and the freezing/thawing cycle that often occurs throughout the winter months.
Several things can be done to increase the likelihood of mums surviving our Iowa winters.
• Select a variety that is cold hardy. Mums purchased at the local florist shop typically are not hardy and are best enjoyed indoors. Check labels carefully or ask about the hardiness of the mum you are purchasing.
• Do not fertilize plants in late summer/fall to discourage late season growth.
• Do not cut back mum plants in the fall as the foliage left standing adds extra protection for the root system.
• Apply a good layer of mulch over the plant in late fall to help reduce the thawing/freezing cycle. Remove mulch in early spring as new growth is beginning to show.
• Avoid planting in areas where the cold, dry north winds will damage them. Select a somewhat protected area.
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Just a couple other suggestions to help make garden mums thrive. They perform best in moist, well-drained soils and full sun. Incorporating compost, peat or cured manure into the soil increases plant performance.
Mums can be easily divided in spring as new growth appears. Each division should include several shoots and a portion of the root system.
Most mums are improved from pinching several times in spring and early summer. Pinching produces bushier plants and more blossoms. When new shoots are about 6 inches tall, pinch out the shoot tips and new shoots will develop along the stems. Repeat this process several times, stopping around the Fourth of July, an easy date to remember. Later pinching prevents the plant sufficient time to form new flower buds for fall blooming.
Sometimes we just want a new splash of color in pots around our home or in the garden. Mums provide great fall color. It’s OK to treat them as an annual, throwing them in the compost when done blooming rather than trying to keep them for the next growing season. However, you use them, enjoy the season by adding some mums to your home or garden.
For gardening questions, call the Linn County Extension Master Gardener Hortline at (319) 447-0647.