QUESTION: I bought pots of mums last fall and planted them in the ground after they finished blooming. They died back over the winter, but grew back this spring. I’ve heard that they should be trimmed after they start to grow, but how much should they be cut?
Those ubiquitous pots of cheerful chrysanthemums that appear in garden centers in late summer are referred to as florists mums. Planted in full sun in good, well-drained garden soil, they should indeed return year after year.
The shoots can begin to appear early in spring. Garden experts advise pinching off the tips of florists mums after they reach 5 – 6 inches tall. As they continue to grow, keep pinching, nipping off the top pair of leaves, throughout the spring and early summer to encourage more lateral growth (making the plants fuller and bushier). This will also delay flowering until late summer and fall, when these bright spots of color will be welcome in the garden.
Keep pinching until about mid-July, then allow the plants to begin to form buds, which will start to flower as fall approaches, about the time many other things are beginning to shut down.
Mums seem pretty resilient. In my own garden, which is more dappled sun and shade than full sun, the mums quickly grow tall and rangy, and I cut them back more severely – sometimes as much as three or four inches off the tops of the plants (I’ll give them a final trim this week). Still, they continue to grow tall, and flop over to cover the garden in a patchwork quilt of colors each fall.