National Gardening Association Editors
When an established perennial produces fewer flowers, or the center of the plant looks sickly while the margins thrive, it could be time to divide the plant. Or even if the plant is healthy, perhaps you’d like to share it with a friend by splitting off a piece. For one reason or another, most gardeners will need to divide their perennials at some point.
The best time to divide plants depends on your region. In cold regions, early spring is usually the best time. The new divisions will have a more time to become established before the challenges of the long, cold winter. On the other hand, in climates with mild winters and hot summers, high temperatures pose a harsh threat, so fall may be a better time to divide, giving plants the mild winter to get established. Here are some guidelines for dividing perennials.