When is best time to divide perennials

Asked April 8, 2017, 9:23 AM EDT

How early can I did and divide daylillies, bleeding heart, and euchera? Can I divide large spirea shrub? Do I cut it down to ground first?

Sherburne County Minnesota dividing perennials horticulture

1 Response

If the soil isn't too wet, this is a good time to divide most perennials, but it's best to divide some in late summer or fall. Following is a list of commonly grown perennials and the best time to divide them:
http://www.extension.umn.edu/garden/landscaping/implement/DividingPerennials.htm

Daylilies--spring or immediately after flowering
Bleeding heart--spring
Heuchera--spring or fall

You might be able to divide the spirea by digging up the root ball and chopping it into suitable sized pieces. Each piece should have healthy roots attached to viable stems. Cut the stems back somewhat before digging and replanting.

For more certain positive results, follow the propagation methods recommended in this North Dakota State University bulletin:

"Japanese spiraea reproduces aggressively in the wild. A single plant can produce hundreds of seeds that remain viable and persist in the soil for many years. Typically the seeds are dispersed by water and deposited along stream banks. They also are distributed in fill dirt. In cultivation, sucker division or softwood cuttings rooted under mist in a warm place during the summer usually propagate Japanese Spiraea. Hardwood cuttings can be rooted outdoors in the fall. Pegging down a branch in the spring, and potting it up in the fall also may layer this plant. Spiraeas are easy to transplant. Fall is the best time to divide plants, but spring and fall are both good for setting out new ones."

Go here to read the complete bulletin:
https://www.ndsu.edu/pubweb/chiwonlee/plsc368/student/papers02/ddevine/spiraea.html