Clethraceae (Clethra)

Protocol Information for:

Label_title:
Clethra (alnifolia)

Family Names:

Family Scientific Name:
Clethraceae

Family Common Name:

Scientific Names:

Genus:
Clethra

Species:
alnifolia

Scientific Classification:

Scientific SubSpecies:

Species Authority:

Scientific SubAuthority:

Authors:

William Errickson

Common Synonym:

Genus:

Species:

Synonym Classification:

Synonym SubSpecies:

Species Authority:

Synonym SubAuthority:

Other Information:

Common Name:
Summersweet, Sweet Pepperbush, Coastal sweetpepperbush

Species Code:
CLAL3

Ecotype:
Central New Jersey

General Distribution:
Clethra alnifolia occurs from Florida to east Texas, and north to southern Maine, southern New Hampshire, Massachusetts, southeastern New York, and eastern Pennsylvania

Known Invasiveness:

Propagation Goal:
Plants

Propagation Method:
Vegetative

Product Type:
Container (plug)

Stock Type:
1 Gallon Container

Grow Time:
12 to 16 months

Target Specifications:
12-18" Height, Well rooted

Propagation Collection:
Summer softwood cuttings approximately 12" long were collected from wild populations in Central New Jersey in June and early July from healthy plants. The cuttings were kept moist and placed inside a soft insulated bag used for field collections.

Propagation Processing/Propagule Characteristics:
The cuttings were kept moist and stored in a walk-in cooler for 2 days or less before sticking.

Pre-Planting Propagule Treatments:
Cuttings were cut to 4 to 6" lengths with at least 2 nodes, having an angled cut on the bottom and a straight cut on the top and leaves were trimmed to approximately 50%. The bottom of the cuttings were dipped in Hormodin 1 (0.1% IBA) powder and stuck in 2" cells filled with high porosity peat-based medium.

Growing Area Preparation / Annual Practices for Perennial Crops:
The stuck cuttings were placed on mist tables in an unheated greenhouse with ventilation. Intermittent mist was supplied for 6 seconds every 10 minutes.

Establishment Phase:
Cuttings were well rooted in 6 to 8 weeks with a 85 to 90% success rate.

Length of Establishment Phase:
6 to 8 weeks

Active Growth Phase:
Well rooted cuttings were transplanted to 1 gallon containers filled with peat based growing media supplemented with Caliber-cote controlled release fertilizer (18N–6P2O5-12K2O).

Length of Active Growth Phase:
10-14 Months

Hardening Phase:

Length of Hardening Phase:

Harvesting, Storage and Shipping:
One gallon containers were finished the following season by June or September.

Length of Storage:

Guidelines for Outplanting / Performance on Typical Sites:
Grows in wet woods, thickets, marshes, swales, bogs, and along lake and stream edges. Will grow in average soil provided there is enough moisture. Flowers in shade.

Other Comments:

References:
https://plants.usda.gov/DocumentLibrary/plantguide/pdf/pg_clal3.pdf

Citation:
Errickson, William. 2025. Propagation protocol for production of Container (plug) Clethra alnifolia Plants 1 Gallon Container; Rutgers New Jersey Agricultural Experiment Station Cream Ridge, New Jersey. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2026/05/21). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

Personal tools