While there is something to be said for spontaneity, planning is key when it comes to things like dinner and retirement. It’s also crucial when it comes to dividing plants. Fall is one of the best times to dig and plant perennials—those plants whose roots survive our winter’s cold so they can get growing again in spring. Perennials are the hardy beauties whose reputations for resilience are what land them in our Midwest landscapes.

Most of my dividing skills were honed when I had to move plants around to make room for new additions. Some, like Hostas, peonies, and Hellebores, can go beyond a decade without need of division. Others, like Astilbe, Salvia, and Veronica will do best when they’re divided every three to five years.

Three basic reasons for dividing perennials:

1. Maintaining the health of the plant – A plant that is overcrowded just doesn’t perform as well as it could. That means its blooms are smaller and fewer in number, and it loses its ability to withstand threats like insects and disease
2. Sharing the wealth – Like borrowing, only better, sharing a plant tends to be more permanent, especially if the giver knows how to divide a plant
3. Pursuit of more plants – Although experts recommend having a spot in mind before buying a plant, the reality is that most gardeners buy plants without a clue about where it will go until they get it home or it arrives in the mail. At that point, it’s likely that the current resident plants will have to relocate to make room for the newcomer.

The number one reason is often the most challenging to determine, but these are most common.

Signs that it’s dividing time:

• You can no longer see soil around several plants. This will happen with daylilies when they are in need of rejuvenation.

• The plant has trouble supporting its stems, especially those around the plants’ edges. This often is seen in Liatris and Phlox.

• A flowering plant’s blossoms are smaller or less plentiful, or leaves are smaller than normal.