Dividing and Transplanting Perennials

Perennial plants bring color and structure to our garden year after year. After several years of maturity you may notice that some perennials start to thin out in the middle or produce fewer or smaller blooms. This is a sign that these perennials need to be divided. Division stimulates growth and reduces competition, returning plants to a more manageable size and shape.

October is a great time to divide plants – the cool, often overcast weather prevent the soils from drying out quickly. It is always helpful to divide right after a rainy period, as the soils will be softer and the plants will be well watered and able to survive transplant stress better. Plants that bloom in spring and summer should be divided now – if asters, anemone, and other fall bloomers are divided now there is a good chance they won’t bloom. Additionally, spring and summer bloomers can focus all their energy on establishing roots before the ground freezes.

The process of division is simple; you dig up the plant at the dripline using a spade or fork, separate the plant into smaller pieces with at least 3-5 shoots and healthy roots, and replant them in your garden or gift them to friends and neighbors.   

Treat divisions as if they were new installations; keep them watered and protected from bad weather for a few weeks. Some plants need additional care and monitoring after division, including Goat’s Beard (Aruncus sp), Milkweed (Asclepias sp), Peony (Paeonia sp), Russian Sage (Perovskia atriplicifolia). Plants with tap roots need to be very carefully dug up and divided, others just need some additional organic matter and careful water monitoring.

Prepared by Lindsey Smith, Collections Curator