I must admit I am enjoying my perennial garden this spring. The cooler temperatures meant some flowers lasted longer, and timely rains provided much needed water. Now if I could just find someone to help pay for my mulching addiction life would be almost perfect in the garden. But as I have been working through the beds I have noticed one chore not yet checked off my list: pinching perennials.
Pinching removes the growing point of the stem, resulting in a development of side shoots. Pinching or cutting back perennials will result in a nicer appearance in the garden, since a plant that has been pinched often is shorter, stockier and less likely to flop over. It also reduces the need for cumbersome staking.
Many plants produce one long shoot ending in a flower later in the season. By pinching or cutting back, that one shoot can be turned into two, four or more, each ending in a flower. Some plants should be cut back only once, while others can be pinched a couple of times.
The classic example is garden mums. When the mum reaches about 6 inches high, cut it back to about 3 inches. A few weeks later when the plant reaches 6 to 8 inches again, cut it back to 4 or so inches. This process can be repeated until July 1. Growth produced after this period will need to develop for fall flowering. Fall asters can also be treated this way.
Several other garden perennials benefit from a onetime pinching, including:
▪ Sedum (Autumn Joy)
▪ Solidago (Goldenrod)
▪ Platycodon (Balloon Flower)
▪ Eupatorum (Joe Pye Weed)
▪ Nepeta (Catmint)
▪ Monarda (Beebalm)
▪ Garden phlox (Phlox paniculata)
You can pinch stems back one at a time or use hedge shears for thicker stems. Hedge shears make short work of my large clump of mums.
Hand pruning one at a time does leave the plant in better condition as the placement of the cut can be controlled. Ideally you would make the cut just above a leaf. The new shoots will develop from the axial of the leaves. This happens as the dominance of the stem is transferred to many dormant buds in the plant.
But whether you selectively cut or just whack it back, it’s akin to a bad haircut. Give it a couple of weeks to grow out and all is forgiven.
Give it a try and hopefully you will find your garden a little more manageable this season. Guess I have another chore to add to my to-do list as I spend a few more quality hours out in the garden.
Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Got a question for him or other university extension experts? Email them to firstname.lastname@example.org.