Six Perennials to Divide in September for a Healthier Garden
Gardening Know How advises dividing six specific perennials in early fall, while warning against disturbing three others until spring.
September is the ideal month for dividing many spring and summer-blooming perennials. The source, Gardening Know How, states that cooler air and warm soil reduce plant stress and give transplants time to establish before winter.
A general rule is to divide plants about four to six weeks before the ground freezes. The task is best suited for perennials that appear overcrowded, are flowering less, or are spreading too aggressively. Fall-flowering plants should be left undisturbed.
Plants to Divide Now
The publication lists six perennials that benefit from division in early September.
Garden phlox, a summer bloomer, should be divided if clumps look old and crowded. Water it well beforehand, then dig up the clump. Ensure each new division has healthy roots and several shoots, and replant immediately at the same depth.
Astilbe typically needs dividing every three to four years. Its fleshy root system allows for creating multiple new plants. Lift the clump and use a sharp tool to cut the crown into sections, each with roots and growing parts. Replant divisions right away.
Spiderwort can be divided whenever it becomes crowded. After digging up a clump, gently brush away soil to see the roots. Divisions can often be pulled apart by hand, provided each has several healthy roots and shoots.
Veronica, or speedwell, is easy to divide after its flowers fade. This leads to bushier spring growth. Divide every three to five years, or when plants show a dead center. Use a sharp knife on the tough roots, discarding the woody center and using fresher outer growth.
Oriental poppies begin new growth in early fall after summer dormancy. They usually need division every five years, or when flowering reduces. Their long taproot makes dividing challenging. Dig deep, water first to soften soil, and use a sharp knife to cut sections, each with part of the taproot and shoots.
Asiatic lilies are ready as their foliage fades. Dig up the roots and look for offsets or bulblets to separate from the parent bulb. Replant these immediately and do not let them dry out.
Plants to Avoid Dividing
The source strongly advises against dividing three types of perennials in the fall.
Tips for Successful Division
Mary Ellen Ellis, a gardener with over 20 years of experience, provides key guidelines through the source. Always perform division on a cool, cloudy day. Prepare the new planting site in advance. Get divisions into the ground immediately to minimize stress.
Be selective. Not every crowded plant should be divided in autumn. Following these steps will help ensure healthy, expanded plantings for the following growing season.
