How to Prune Asters
To create a sturdier, fuller aster with an increased number of flower buds, try pinching your asters. Asters are fall blooming perennials available in a wide array of colors and heights. Pinching refers to the removal of the terminal buds on each stem. Removing this bud allows the lateral buds to grow. This growth will develop a stronger plant with more flowers. Asters can be pinched 2 to 3 times a growing season. Taller asters can sometimes become floppy and spindly and require staking.
TIP: Our expert gardening advisor, Karen Thurber adds, "Pinched asters will be more compact, with a stronger base, and will require less staking."
How to Pinch Asters
Pinching is done just as it sounds, grasp the stem between your index finger and thumb and squeeze until the tip of the stem breaks off. Do this to each stem to create balanced growth.
TIP: Karen advises, "Pruning shears, rather than your fingers can be used to pinch your asters. To achieve the same result, trim 1/3 of the new growth a few times during the growing season."
When asters are about 6 inches tall, they are ready for their first pinch, remove 2 inches. The second pinch will be when they have reached 10 to 12 inches tall. Again remove 2 inches of new growth over the entire plant. The last pinch needs to occur before July 4th. Any pinching done after this time will delay flowering.
At the end of the growing season, trim the plant to leave just an inch or 2 above the soil and cover it with mulch to protect the plant through the winter cold. This will allow the plant to grow again the next growing season. With pinching, you can develop your aster into the shape and size you desire.