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The Forest Service National Center for Reforestation, Nurseries, and Genetic Resources (RNGR) is a leading source of technical information for nurseries and land managers regarding production and planting of trees and other native plants for reforestation, restoration, and conservation.

 
NPN Protocol Details Image

Clethra (acuminata)

John M. Englert
USDA NRCS - Norman A. Berg National Plant Materials Center
Bldg. 509, BARC - East, E. Beaver Dam Road
Beltsville, Maryland 20705
(301) 504-8175
(301) 504-8741 (fax)
john.englert@wdc.usda.gov
http://plant-materials.nrcs.usda.gov/mdpmc/
Family Scientific Name: Clethraceae
Family Common Name: Clethra family
Scientific Name: Clethra acuminata
Common Name: mountain sweetpepperbush
Species Code: CLEACU
Ecotype: Cumberland Gap National Historical Park
General Distribution: Sw. Pennsylvania to e. Kentucky and w. Virginia, s. to Tennessee and ne. Georgia. Found in rich woods in the mountains. (Gleason and Cronquist, 1991). It has not been found in Maryland. (Brown and Brown, 1992.)
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 2 or 3-gallon container shrubs
Time To Grow: 0
Target Specifications: Finished height: between 48" and 72" in 3 gallon containers.<br>Root system: fibrous root ball that fills a Spin-Out treated container.
Propagule Collection: Source: Cumberland Gap national Historical Park, KY. Seed was also collected from mature Cumberland Gap container plants in the NPMC nursery.
Collection dates: February, 1992 and October, 2000. .
Propagule Processing: Cleaning: Seeds were either shaken from the dried capsules, or the capsules were crushed and seed was extracted. The seed is extremely small.
Storage: Cleaned seed is stored dry in seed envelopes or sealed containers in a cooler at 40F. and 35% relative humidity.
Pre-Planting Treatments: No pretreatment is indicated. (Dirr and Heuser, 1987).
Growing Area Preparation/
Annual Practices for Perennial Crops:		 Propagation environment: Because seed is so tiny, it was started in flats under artificial light in an indoor propagation area (a converted office) rather than outdoors in the woody nursery beds or in the PMC greenhouses. (Temperature fluctuations in the greenshouse have resulted in seedling mortality in the past.) Temperatures were maintained at around 70-75F with 24 hour fluorescent lighting set about 4-6" above trays during germination.
When seedlings reached transplant size they were moved to greenhouse benches.
Establishment Phase: Sowing date: late winter or early spring; however, seedlings started on 3/1/01 were not ready for bump-up to quarts until late August.
Sowing technique: Seeds were surface-sown in 4"x4" trays filled with screened peat or fine germination mix and given a fungicidal drench. The 4x4's were placed in solid-bottomed 10x20 trays with clear plastic covers to prevent dehydration and were bottom-watered to keep evenly moist.
Emergence: seeds germinated readily in 11-14 days.
Transplant: between 4 to 8 weeks, tiny seedlings were separated and transplanted individually to multipots in a mix of Sunshine #1 and slow release Nutricote with micros (18-6-8) at 20 oz ber bale of mix. Supplemental water soluble fertilizer was supplied approximately bi-weeklyat rates for sensitive plants.
Extended 14 hour day lengths were provided in the greenhouse. Multipots were moved in mid-June to protected shade outdoors for the summeer where they were hand-watered. Survival was about 60%. Seedlings were subsequently bumped up to quarts the first season.
Active Growth Phase: Bump-ups: plants were bumped up in spring to the next pot size or repotted in the same sized container with fresh media if the root ball was not full. A custom woody mix was used (3.8 cu. ft. Sunshine #1, 4 cu. ft. pine bark mulch, 20 oz. 180 day controlled release 18-6-8 with micros, and endomycorrhizae). Containers spent the growing season in a shade house with overhead irrigation.
Hardening Phase: Irrigation was decreased in the fall as the plants entered dormancy.
Harvesting, Storage and Shipping: Larger container plants are overwintered outdoors under microfoam. Dead leaves and debris are removed from the containers of dormant plants prior to storage. Pots are watered, overlapped on their sides on weed barrier fabric and covered with a microfoam insulating blanket. Rodenticide baits are placed at intervals under the blanket to discourage gnawing rodents. The microfoam is then anchored/
Length of Storage: Early December to mid-March
References: Brown, Russell G. and Melvin L. Brown. 1992. Woody Plants of Maryland. Port City Press, Baltimore, MD.
Gleason, Henry A. and Arthur Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden. Bronx, NY.

Citation:

Davis, Kathy; Englert, John. 2006. Propagation protocol for production of Container (plug) Clethra acuminata plants 2 or 3-gallon container shrubs; USDA NRCS - Norman A. Berg National Plant Materials Center Beltsville, Maryland. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/01). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.