Hydrangea (arborescens)

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/

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Family Scientific Name:	Hydrangeaceae
Family Common Name:	Hydrangea Family
Scientific Name:	Hydrangea arborescens
Common Name:	Hills-of-snow hydrangea
Species Code:	HYDARB
Ecotype:	Cumberland Gap National Historical Park, Shenandoah National Park, George Washington Memorial Parkway
General Distribution:	South New York to Ohio, Missouri and Oklahoma, south to Georgia, Lousiana, and Arkansas.
Propagation Goal:	seeds
Propagation Method:	seed
ProductType:	Plug + (container-field grown hybrids)
Time To Grow:	0
Target Specifications:	Stock Type: Woody plug, container shrub. Height: Varies depending on container, use and site. 2-3 gallon container specimen: 36-48"; 2" plug: 4-5". Root System: Roots of finished plant should fill container.
Propagule Collection:	Collected at George Washington Memorial Parkway, Overlook #2 by J. Kujawski on 8/19/96; and by D. and G. Meyer on 10/14/94; Shenandoah National Park, Skyline Drive, Miles 102-105 by J. Englert in 8/92, 9/92 and 10/92; Cumberland Gap by J. Englert on 10/25/94 and 10/5/96.
Propagule Processing:	Seed Processing: Seed was collected in the Parks in September, October and November and allowed to dry completely in the seed heads. Heads were tapped upside down in a paper bag or on paper to collect seed. If heads are rubbed, screen through 1/22 to eliminate most of the garbage. Seeds/Kg: Unknown. Seed is extremely small. Germination: Untested. Purity: 60%.
Pre-Planting Treatments:	Seed Treatments: None.
Growing Area Preparation/ Annual Practices for Perennial Crops:	Propagation Environment: Greenhouse with alternating day-night temperatures. Provide mist and 24 hour fluorescent lighting during germination. Extended 14 hour day length (high intensity lights from 4:30-10:30 p.m.) for about 2 months post germination. Seed Propagation Method: Seed is very small and has to be hand-sown. Because of this, seedlings are started in the greenhouse. These plugs are either sent directly to the park the same year or are lined out in the National Plants Materials Center woody beds and grown for two years. They are harvested from the woody beds in the fall and either are sent bare root to the park the following spring or are potted up as specimens and grown in our shade house for another two years or until they reach the container size designated by the contract. Container Type and Volume: For planting into the National Plants Materials Center woody beds, seed was started in 406 germination plug trays, transplanted to 72 plug trays, 2" pots or Ropak multipots then plugged out into the field. For container specimens, bare root seedlings were harvested from the woody beds in December, over-wintered in cold storage, potted up the following spring and bumped up in successive seasons to gallon and 2-3 gallon pots depending on finished size specified by the Park. Growing Media: Started in Fafard Germination Mix, transplanted into Sunshine #1 plus 180 day Nutricote SR 18-6-8 at 20 oz. per batch or 0.15 lb. per cu. ft. mix. Larger container plants are potted in a woody mix (3.8 cu ft. bale Sunshine #1, 4 cu. ft. of pine bark mulch, 20 oz. Nutricote and approximately 20 oz. endo-mycorrhizae).
Establishment Phase:	Sowing Dates: January 8, 1998 and November 3, 1999. % Emergence and Date: Huge numbers of seedlings (i.e. about 3,000 from 0.2 g seed) emerged within 7-14 days. Seedlings were so dense they had to be transplanted in clumps and thinned as they grew. (See 'Sowing/Planting Technique'). Sowing/Planting Technique: Seed was mixed with 4-8 grams of talc and surface-sown over moist germination mix in 406 germination trays. (Suggest going with smaller amounts of seed and more talc since seed germinated in clumps of 3-8 per cell). Drenching seed trays with fungicide (we used Triathlon) reduce fungal growth on media surface. Trays were placed under mist (10 seconds at 30 minute intervals) and 24 hour fluorescent lighting for about 10 days until germinated. Establishment Phase: Seedlings germinated quickly but failed to put on much growth during January and February. Seedlings were transplanted 50-60 days post germination to larger containers in clumps as individuals were too small to separate. They were grown under extended (14-hour) day length. Foliage was cut back at about 3" to encourage development of stronger, less succulent, stems.
Active Growth Phase:	Rapid Growth Phase: Began in April. Plugs filled out in April and May and were ready for field planting in June.
Hardening Phase:	Hardening Phase: Plugs were set outdoors in a protected location out of direct sun for about 2 weeks prior to outplanting in the field and at the Park.
Harvesting, Storage and Shipping:	Total Time to Harvest: In 1998 - 18-20 weeks from germination to finished #72 sized plug. In 2000 - 24-26 weeks from germination to finished plug in multipots. (This longer finishing time was probably due to unreliable heat inour greenhouse during the winter and the larger plug size in the multipots.) The plants take approximately two years to grow from plug to bare root size in the woody beds and another 2 years to finish in containers as specimens. Specimen plants are bumped up to the next larger container size approximately yearly and held during the growing season in a shade house. Harvest Date: Bare root plants are harvested dormant from the National Plant Material Center woody beds in December after two growing seasons. They are tied in bundles and packed in moist sawdust for over-wintering. They are delivered to the park as bare root stock the following spring or potted up as specimens and grown to finished size in the shade house. Storage Conditions: Bareroot stock is overwintered in National Plants Materials Center cold storage at 40186;F, 35% relative humidity Larger container specimen plants are over-wintered outdoors under microfoam. Storage Duration: December - March or April.
References:	Gleason, H and A. Cronquist, Manual of Vascular Plants of Northeastern United States and Adjacent Canada. 2nd edition. 1991 New York Bot. Garden,

Citation:

Davis, Kathy M.; Kujawski, Jennifer. 2001. Propagation protocol for production of Plug + (container-field grown hybrids) Hydrangea arborescens seeds USDA NRCS - Norman A. Berg National Plant Materials Center Beltsville, Maryland. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/02). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.