Chrysanthemums:

All You Ever Wanted to Know

Hardy chrysanthemums (“mums”) provide great fall color in the home garden.  They come in a wide variety of colors (except blue), sizes and flower shapes.  Everyone knows of, or owns, mums that seem to survive and bloom year after year with little or no care.  Most of them, however, require a good deal of maintenance to survive in the garden.  It might be best for the busy gardener to visit the Nursery every year in late summer to buy these fall beauties.

Annual Maintenance

Division.  Each year in the spring, just when the plants begin to show a bit of growth from the base, lift the entire plant and you will notice many pale stolons, usually with a tuft of small leaves at the end, spreading out among the darker roots at the base of the plant.  Each stolon can become a large plant by fall, so cut off as many as you need and discard the rest of the old clump.  Small divisions of stolons make the best plants.

Care of the Plants.  Be aware that though mums require abundant moisture while they are growing, they must be in well-drained soil to survive the the winter.  Therefore, try not to plant them in heavy clay soil.  Since mums are heavy feeders, they should be set out in soil rich in compost supplemented with bone meal.  Supplemental feeding with a balanced fertilizer during the summer is important.  Water well during dry spells.  Mums are shallow-rooted plants so please provide adequate protection, typically mulch, in the winter.  Once their flowers and foliage have been frost-killed, you may cut them back to the ground.  To prevent the alternate freeze-thaw of our Michigan winters, cover them with an airy mulch such as shredded bark, straw, evergreen boughs, or a basket held down with a rock.

Pinching Back.  As soon as the plants reach 6-8” high, pinch them back about halfway.  Once the new growth is 6-8” long pinch again and continue this until July 15th when flower buds should be initiated.  Ultimate size should be 15-18” dense, bushy plants with the expected surface covering of brightly colored blooms in late summer/early fall.  Since shorter periods of daylight induce mums to bloom, DO NOT plant them where they will get bright light during the evening.