Fall is a good time to get ready for next year’s display of spring-blooming perennials. Some may need repositioning, some may have lost vigor as a result of crowding and some may be in need of dividing. Most perennials will transplant easily in October. Some root loss is inevitable, so the shorter, cooler and rainier days of autumn are a less stressful time to move plants. Since it’s not recommended to relocate perennials while they’re flowering, species that bloom in late summer or fall (Chrysanthemum, Sedum, etc.) are best moved in spring when the first shoots emerge from the soil.

Bleeding Heart transplants well in the fall. Photo: Colorado State University

 

When moving perennials, cut them back, divide if necessary and include as much of the root system as possible when digging. (As a rule of thumb, pull apart fibrous-rooted perennials with your hands or using two garden forks and cut apart the fleshy-rooted ones with a sharp knife or spade.) When planting, be careful to maintain the same soil level as their previous location (not planting either too deeply or too high). Soak thoroughly and then following up with a periodic light watering (in the absence of rain) will help roots to get established in their new location. Very important to the survival of fall-transplanted perennials is the application of about 3” of mulch or compost. This will keep the soil moist and avoid wide fluctuations of soil temperature which could result in frost heaves which can lift plants right out of the ground. Do not fertilize until spring. Below are some common perennials that do well when transplanted in the autumn.
Asiatic Lily
Astilbe
Bleeding Heart
Daylily
Japanese Iris
Lily-of-the-Valley
Oriental Lily
Oriental Poppy
Peony
Siberian Iris
Veronica