Ever wonder why during the second year your garden mums don't grow as dense and compact as they were when you bought them at your local nursery and garden center the previous fall? There's a reason. The commercial growers, who grew the plants in containers, pinched them a couple times during the growing process. They probably also used growth regulators to control the height and overall size.
So, is there something you can do to make your garden mums bushier and more compact once they are growing in your garden? Yes. You won't be using growth regulators but some simple snipping or pinching during spring through mid-summer will provide you with not only a denser plant but one that will bloom on time: during the cooler weather of fall.
You don't have to pinch your mums but, in order to grow a bushier, more compact plant, and one that will bloom on time (during Fall) and produce more flowers, some pinching will be required.
What is pinching?
Pinching involves the removal of stem tips. Pinching can be done with your finger tips or a pair of hand shears or sharp pruners. If you don't have long or strong finger nails I'd suggest a sharp pair of bypass hand pruners.
How To Pinch
You can pinch the stem tips on the mums growing in your garden for the first time in spring: when the shoots have emerged and grown to approximately 6 inches tall. Pinch the stem just below the first set of leaves. Beneath where you pinched, new lateral (side) branches will develop along the stem. As soon as these new side branches become 6 to 8 inches long, the tips of these can be pinched. You can continue pinching like this until early July. I usually cease pinching around 4th of July because this is an easy date to remember. For some mums, which I know to be later bloomers, I might pinch a little beyond this time. I usually pinch about two or three times during the season.
What Happens If I Don't Pinch?
Depending on the variety of mum (some naturally grow more dense), and environmental factors, there's a good chance the plants will stretch: grow tall and leggy. There's nothing wrong with this as this is the natural growth habit of many varieties of mums. However, if the stems grow too tall and leggy, it might require that you stake the stems while the plant is flowering. Long stems have a tendency to become floppy and will bend over from the weight of the flowers, especially during a rain.
How To Care For Mums After The Fall Bloom
After your mums have finished blooming in the fall, and the foliage has gone completely dormant, you can cut the dead stems back to just above the ground. That being said, northern gardeners can leave the dead stems there to help protect the roots from severe cold weather during winter. No matter what region you garden in, it's a good idea to apply a 2-inch layer of pine straw or shredded wood mulch around the roots of your mums. If you place mulch directly on top of the plant make sure to remove it in late winter so that the new growth can emerge without being damaged.