Question of the Week – Number 2: November 2, 2017
“Neil, What should I do with my mums once they finish blooming?”
You’re familiar with many types of chrysanthemums. The big corsage “football” mums are the result of careful training and of removal of all but the one main floral head. Potted chrysanthemums, similarly, are “disbudded” to leave fewer heads of greater size.
So called “garden mums” used to be known by the descriptive term of “cushion mums” because every flower head was allowed to develop. The plants looked like colorful pincushions.
Garden mums grow to be 18 or 20 inches tall and 24 inches wide, and they literally cover themselves with scores of smaller flowers in all the fall tones.
But what do you do when your mums have finished their bloom cycles in autumn? That’s starting to happen, as evidenced by the aging of the flowers. Lighter colors turn purplish as they start to dry out and die. You can gain a week or two more by pick-pruning those dried flowers out with small shears, but eventually you’ll have to make a more dramatic decision.
When the flowers are wrapped up and done for the season, cut your plants back to within 1 to 2 inches of the ground. You’ll see some very small new growth starting to emerge from the bases of the plants, and that growth will be the stems for next year’s plants. Leave the old stem stubs in place to act as markers so you won’t accidentally break them. When spring comes, those shoots will start to grow very quickly, and soon you’ll be back in the mum-growing game.
If you ever want to dig and divide your mums, those new shoots are your guideline. You can lift the clumps out sometime this month and break them into pieces each containing two or three of those shoots. Replant them immediately into well-prepared garden soil. Set them on 18-inch centers, and keep them moist throughout the winter. Each old clump will yield three or four new plants.
Don’t be surprised if your garden mums produce buds and blooms next spring and early summer. Mums measure the length of the dark periods at night to determine when it’s time for them to flower. When nights reach 12 or 13 hours of uninterrupted darkness each night the flowering hormones accumulate and call for production of buds.
That happens, of course, in the fall, but there is a like time in the spring. You can enjoy those spring blooms for a while, but a process known as “heat delay” will hit them by early summer, at which time you’ll want to trim the buds off and force the plants to grow vegetatively until fall.