You’ve carefully tended your garden but now some of your perennials are a little overgrown. Dividing perennials ensures that the plants will stay healthy through judicious thinning. It’s also a great way to multiply the number of plants that you have in a garden.
Try to divide perennials every three to six years depending on the overall growth of the plant. Not all perennials can be divided, but those plants that have a clumping root system, and not a tap root system can usually withstand dividing. The best time to divide summer and spring blooming plants is in the late summer just before the first frost. Plants that bloom in the fall should be divided in the spring.
Step 1: Starting a few days before you intend to divide your perennials, start watering them regularly. This will ensure that the plant is well hydrated and ready to withstand the shock of being divided.
Step 2: Plan on dividing the plants just before sundown or on an overcast day. Hot, sunny weather can distress plants and increase the chance that the plants could go into shock and die.
Step 3: Dig up the perennial you intend to divide. To complete this task, use a spade to cut a hole around the base of the plant that is 12 to 24 inches in diameter to accommodate the root ball. Then use the shovel to carefully pry the plant from the ground.
Step 4: Divide the plant using a soil knife to cut apart the plant. Each division should contain several vigorous and healthy stems as well as a significant share of the root ball.
Step 5: Fluff the root ball of each new division, encouraging the roots to expand. This will encourage the perennial’s root system to grow beyond the cuts you have just created.
Step 6: Plant each division in healthy, moist soil. Replant one division in the hole created by the old plant, adding additional soil to the hole to fill it completely. Water daily and take particular care of the new divisions until each plant has established itself in a few weeks.