Buttonbush (Cephalanthus occidentalis) can be propagated most easily through softwood cuttings in spring or hardwood cuttings in fall, or by sowing seeds in the fall.
Here’s a more detailed explanation:
1. Cuttings:
- Timing: Spring is ideal for softwood cuttings, while fall is better for hardwood cuttings.
Stem Cuttings:
- Take 4-6 inch stem cuttings from new growth, ensuring they have a node and some leaves.
- Cut the stem below a node using a sharp, clean knife.
- Remove lower leaves, keeping only the upper leaves.
- Dip the cut end into rooting hormone.
- Plant the cuttings in moist soil, keeping the soil moist and in bright, indirect light.
- Roots should develop in a couple of weeks.
Hardwood Cuttings:
- Take cuttings in the fall from mature stems.
- You can directly plant hardwood cuttings into wet soil along pond edges, stream banks, or wetter areas.
- Apply rooting hormone to the cut and plant in a nice mix of soil and compost.
- Cover with plastic to create a greenhouse effect, and leave in some cool shade until about September.
Unrooted Cuttings:
- Unrooted cuttings can be pushed into moist soil along shorelines and will establish on their own.
2. Seeds:
- Collection: Common buttonbush seeds are ready for collection in the fall when they have turned reddish-brown.
- Sowing: Sow seeds into moist, humus soils in full sun or part shade.
- No Pretreatment: No pretreatment is necessary for seed germination.
- Germination: Seedlings should emerge in about two weeks.
- Timing: Sow seeds in either fall or spring, ensuring they remain consistently moist for the best germination results.
3. Other Considerations:
- Soil: Buttonbush prefers moist soil and can tolerate very wet conditions.
- Sunlight: Buttonbush prefers full sun to partial shade.
- Establishment: The biggest challenge to establishment of a new buttonbush plant is to control competition during the first growing season.
- Spreading: Buttonbush spreads by seed dispersal and resulting seedling establishment, and also through suckering (individual plants arising from roots).
- Transplanting: You can transplant buttonbush from spring to early summer.