Chrysanthemums, or “mums,” are popular perennials. They offer a wide variety of flower colors, from white and cream to dark maroon and burgundy, as well as numerous growth habits from small dwarf plants to giant shrub-like Maxi-Mums. Mums are easy to grow and can provide years of enjoyment if care is taken to select an appropriate variety, plant in a sunny, well drained, location and provide winter protection.
Plant chrysanthemums from seed or small sets in spring after all danger of frost has passed. Plant large ready to bloom potted plants in late summer and early Fall. Small plants derived from rooted cuttings, divisions, or rooted suckers of old plants can be used. Larger container plants purchased from garden centers may be planted anytime during the spring, summer, or early fall.
Garden chrysanthemums grow in a wide variety of soils but must have excellent drainage conditions. Growth is poor and winterkill likely in poorly drained wet soils. Sunny locations are good sites. Plants in semishady locations will be taller, have weaker stems, and bloom later in the fall. Incorporate 2 – 4″ of peat moss, compost, or well-rotted barnyard manure into the soil. If you use only peat moss or do not add organic matter, apply 3 to 4 pounds per 100 square feet of a complete fertilizer such as 5-10-10 or 5-10-5 in the spring. Sidedressing plants with a complete fertilizer in early August, especially in years of abundant rainfall or irrigation, also is recommended. If the fertilizer applied in the spring is a slowly available type, such as coated or organic fertilizer, the second application may not be necessary. Space plants 18 – 24″ apart, depending on the mature size of the cultivar.
The University of Minnesota has introduced numerous hardy, attractive garden mums over the last 50 years. Early blooming cultivars assure flowering before frost. Late blooming cultivars may fail to bloom before damaging or killing frosts.
Pinching Mums maintain a bushy compact plant form if pinched or pruned regularly. Although newer cultivars do not require pinching, the traditional method has been to pinch out the tip to induce branching and produce stockier plants. Repeat pinching on side branches when they have grown 6″. Continue pinching until mid-June for early flowering varieties, late June for September flowering varieties, and early July for October varieties. Complete pinching by July 4 to assure flowering prior to frost. Very high summer temperatures may also delay flowering. Most mum flowers are resistant to frost; Centerpiece is especially frost-tolerant.
Mums vary widely in cold hardiness. Cultivars listed in the table below have been developed based on years of plant breeding at the University of Minnesota. These plants have been selected for superior flower characteristics, growth habit, and winter hardiness. Most will survive winters in Minnesota. Florist mums, sold throughout the year in supermarkets and greenhouses, may not survive Minnesota winters, and if they do, will probably not flower before hard frosts. Proper location (good drainage and protection from winter winds) and a winter mulch of 4 – 6″ of shredded leaves, hay, straw, or evergreen branches applied as soon as the soil surface freezes is critical to winter survival.
Plant Division Plants can be dug and divided in spring as new growth begins. Stronger shoots are usually on the outside of the clump. Set the growing tip of each division just below ground level. For an attractive display of color, plant at least three shoots in a triangular pattern.
Florist Mums Are attractive blooming potted plants are available through-out the year from florists. After flowers fade, plants can be cut back to 3 or 4 inches and planted in the garden. Florist mums may overwinter, but usually flower too late for USDA Zone 3 and 4.