Cephalanthus

( seff - uh - LAN - thus )

At-A-Glance Information

Commonly called Buttonbush or Button Willow, this genus of deciduous shrubs and small trees needs full sun to light shade and regular to ample water to perform well. The spherical white flower heads on these plants will attract butterflies to your garden. Leaves are bright green, and fragrant flowers bloom in late summer. On average, these woody landscape plants reach between 5 and 15 feet tall when mature. Buttonbush is useful for naturalizing in wet areas and is great in rain gardens or for planting in bioswales. It is also a great plant for wildlife; it is considered a great honey plant and ducks and other water birds and shorebirds consume the seeds. Take care when planting these trees and shrubs in the landscape, as they are toxic to humans, pets and livestock.

Cephalanthus species and varietals

The genus Cephalanthus is a member of the plant family Rubiaceae and includes six species. The genus was recorded by Carl Linnaeus in his publication Species Plantarum in 1753, and its scientific name is derived from the Ancient Greek words kephale (meaning head) and anthos (meaning flower). These shrubs and trees grow well in zones 2-10 and 14-21. To find your zone, click here: Zone Map.

Cephalanthus glabratus (Buddleja glabrata) (Sarandi Colorado)
These shrubs are native to South America, and produce white flower heads that smell slightly like cinnamon. Leaves are green to grey-green and stems are brown to reddish. Plants reach between 10 and 17 feet tall at maturity. 

Cephalanthus occidentalis (Buttonbush, Common Buttonbush, Button-Willow, Buck Brush, Honey-Bells)
​Native to eastern and northern North America, these plants reach about 3-15 feet tall and wide, and can be pruned as shrubs or trees. Flowers are white to pale yellow in color, and bloom in round inflorescences. The California Button-Willow plant is a sub-species.​

Cephalanthus salicifolius (Mexican Buttonbush, Mimbre, Botoncillo, Jazmin Blanco)
Native to Mexico and Paraguay, this species prefers to grow in wet soils, and is commonly seen in riparian zones, in swamps and along pond margins. Plants reach between 8 and 18 feet tall when mature, and produce white spherical flower heads from March through July.

Caring for and pruning Cephalanthus occidentalis Trees

Plant your Buttonbush shrub or tree in a location that receives full sun to partial shade. It will produce more flowers and grow more vigorously the more sun it gets, and thrives in a spot that gets at least 6 hours of direct sun each day. These plants prefer moist, rich soil, and can tolerate their roots being in standing water, making it an ideal planting for ponds, streams, rain gardens, and bioswales. It can also grow in average garden soil, providing it remains relatively moist. After planting, add a 2-3 inch layer of mulch to the soil around the base of the plant to increase soil moisture retention and suppress weed growth. Newly installed shrubs should be watered regularly, especially during dry spells. This will help it to establish a deep root system. Mature shrubs are considered relatively drought tolerant, but do prefer to be growing in soil that is moist or wet. If planted in drier soils, it will need supplemental waterings, especially during prolonged periods of drought. These shrubs and trees do not need to be fertilized; a simple yearly application is sufficient to provide needed nutrients.

Prune these trees and shrubs in late winter to early spring; remove dead, crossing, diseased, or damaged branches and to maintain a handsome shape. These plants can be cut back severely if needed for a rejuvenation pruning or to control size. Buttonbush will grow vigorously under optimal conditions, and may quickly overwhelm areas of the landscape, especially if not enough space was provided at the initial planting time. These are considered hardy in most climates, but may need some extra mulch around their base to help insulate roots during freezing temperatures.

Propagation

Cephalanthus can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your shrub or tree, follow the instructions below:

Propagating Cephalanthus by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In late spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots. 
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Cephalanthus by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows. 
  2. Harvest your seeds. The seed pods on Caesalpinia plants are pretty easy to spot, they're large and dangle from the branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  4. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Cephalanthus trees and shrubs produce nutlets that hold seeds.
Cephalanthus seeds are relatively small.

Problems and Pests

Cephalanthus plants suffer from the following pests and diseases, though on the whole they are considered to be relatively pest and disease free.
  • Leafhoppers
  • Lygus Bugs
  • Thrips
  • Deer
  • Brown Leaf Spot
For information on these problems, see the following links:
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Gallery

The rounded white flower heads look a bit like spiky golf balls, and attract butterflies.
These plants can be grown as shrubs or trees.
Buttonbush is great at filling in greenery and flower interest in landscapes.
California Buttonbush, or Cephalanthus occidentalis.
These shrubs and trees thrive in wet soils.
Cephalanthus provides interest from spring through fall.

Videos

Learn all about Buttonbush.
Check out these wonderful multi-use shrubs.
Learn about these shrubs from a Master Gardener.
Pollinators love these shrubs.

Resources

Cephalanthus occidentalis (Button Bush)
Cephalanthus occidentalis: Button Bush
How to Grow and Care for Buttonbush
Buttonbush: A Growing Guide for Cephalanthus
Wikipedia: Cephalanthus
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 231, Cephalanthus occidentalis
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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