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Tuesday - December 10, 2013

From: Pottsville, PA
Region: Mid-Atlantic
Topic: Pruning, Shrubs
Title: Pruning buttonbush from Pottsville PA
Answered by: Barbara Medford

QUESTION:

In a formally planted park, a small area has become swampy. I have choosen to plant it with wet tolerant native plants. I would appreciate any suggestions on pruning the buttonbush [Cephalanthus occidentalis] to fit into the setting and not become ragged.

ANSWER:

Cephalanthus occidentalis (Common buttonbush) is native to Schuylkill Co., PA as shown in this USDA Plant Profile Map. We always check on this first to make sure gardeners are not spending a lot of effort on a plant that cannot survive the environment where they are being grown.

If you follow the plant link above to our webpage on this plant you will find these growing conditions:

"Growing Conditions

Water Use: High
Light Requirement: Part Shade , Shade
Soil Moisture: Moist , Wet
Soil pH: Circumneutral (pH 6.8-7.2)
CaCO3 Tolerance: Medium
Cold Tolerant: yes
Soil Description: Limestone-based, Sandy, Sandy Loam, Medium Loam, Clay Loam, Clay
Conditions Comments: Common buttonbush is a spreading, multi-branched shrub or sometimes small tree with many branches (often crooked and leaning), irregular crown, balls of white flowers resembling pincushions, and buttonlike balls of fruit. Buttonbush is a handsome ornamental suited to wet soils and is also a honey plant. Ducks and other water birds and shorebirds consume the seeds."

In particular, notice the line: "Buttonbush is a handsome ornamental suited to wet soils and is also a honey plant." You have chosen this plant very well for the conditions you describe. Also on that page is this information: "Trunks are often twisted. Spreading, much-branched shrub or sometimes small tree with many branches (often crooked and leaning), irregular crown." You can see from the pictures below from our Image Gallery that the plant is capable of growing to a very full shape.

From the University of Connecticut Horticulture Department, mention is made of periodic "rejuvenation pruning" to avoid the plant becoming misshapen and out of control. From the Purdue University Department of Horticulture, please read this article about rejuvenation pruning.

The conclusions from both of these academic articles is that pruning is better done on a regular annual basis. Since the plant is deciduous and you should prune woody plants (trees and shrubs) in cool weather, we would advise mentally noting or even loosely tied flags on points at which you plan to prune Although this is by nature a loosely growing shrub, we believe that regular annual maintenance will be better to keep it neat and appropriately sized than the cutting to the ground of rejuvenation pruning.

From the Image Gallery

Common buttonbush
Cephalanthus occidentalis