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Pycnanthemum (curvipes)

Claire Zuidervliet
Conservation Propagator
Mt. Cuba Center
3120 Barley Mill Rd
Hockessin, Delaware 19707
3026600530
czuidervliet@mtcubacenter.org
http://www.mtcubacenter.org/

Family Scientific Name: Lamiaceae
Family Common Name: mint family
Scientific Name: Pycnanthemum curvipes
Common Synonym: Koellia curvipes
Common Name: Tennessee mountain mint
Ecotype: Georgia, DeKalb County
General Distribution: Sw. NC and se. TN south to nc. GA and n. AL; disjunct in nc. TN (Chester, Wofford, & Kral 1997) and wc. KY (where found in 1922 in Muhlenberg County, KY by Vanessa Voelker)
Propagation Goal: Plants
Propagation Method: Seed
ProductType: Container (plug)
Stock Type: Wild
Time To Grow: 14-22 weeks
Target Specifications: Well-rooted 6 inch pot
Propagule Collection: Seeds were collected once flower clusters dried on the plant and stored in a paper bag at room temperature in a well-ventilated, dry environment until cleaning.
Propagule Processing: Seeds were cleaned by rubbing flower clusters against no. 8 and no. 16 Fisher Scientific Company stainless steel sieves to release the capsules and separate larger chaff from the seeds. Seeds were then run through the Oregon Seed Blower at the lowest air flow setting to separate small chaff and unviable seed from viable seed. Once clean, seeds were stored in glassine envelopes inside of airtight containers in a cooler set to 3.8˚Celsius (39° Fahrenheit).
Pre-Planting Treatments: Cold moist stratification was provided to half of the seeds in this collection for 60 days at 3.8˚Celsius (39° Fahrenheit) to determine if pre-planting treatment affects germination rates. Germination rate decreased by 5% with cold moist stratification. Seedlings showed no difference in uniformity or size between treatments.
The recommended procedure in this protocol is to sow seeds directly in a warm environment.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Seeds were hand sown into PenPaks (6" x 2.5" x 4.5") filled with ProMix FPX germination media at a rate of 200 seeds per container. The seeds were left uncovered due to their requirement for light to germinate. Media was kept consistently moist until germination by gently hand watering with a fine droplet-size breaker.

Containers were placed into the propagation greenhouse after cold moist stratification or upon sowing. Bottom heat was provided by hot water tubes under flats with a soil temperature target of 18-24˚Celsius (65-75˚ Fahrenheit). Daytime temperatures varied from 18-26˚ Celsius (65-80˚ Fahrenheit). Night temperature was set at a minimum of 18˚ Celsius (64˚ Fahrenheit). High pressure sodium lighting was utilized to extend the day length to 16 hours.
Establishment Phase: Seeds from both treatments were placed in the propagation house on April 1. Seeds that received cold moist stratification germinated in 5 days after moving to the propagation greenhouse from the cooler and had a 32% germination rate. Seeds that were direct sown in the propagation greenhouse germinated in 8 days and had a 37% germination rate.

Seedlings were moved into a shaded greenhouse with average temperatures of 18-24˚ Celsius (65-75˚ Fahrenheit) 2 weeks after germination. Watering frequency was reduced slightly to encourage root development.
Length of Establishment Phase: 4 weeks
Active Growth Phase: After true leaves appeared and seedlings were sturdy, approximately 4 weeks after germination, they were potted into 5 centimeter (2 inch) peat pots using a commercial perennial potting media amended with bio stimulants and low rates of immediately available 11-5-11 and slow-release Nutricote 18-6-8. At this stage, young plants were moved into an unshaded greenhouse set to 12˚ Celsius (55˚ Fahrenheit) minimum night temperature in early May.

When roots began to show through the edges of the peat pots, approximately 8 weeks after germination, the young plants were potted into 15 centimeter (6 inch) round fiber containers using the same potting media, adjusted to provide a slightly higher rate of fertilizer. No additional fertilizer was added throughout the growing season. Once established, the plants were watered with drip irrigation for 25 minutes when the media was mostly dried out.
Length of Active Growth Phase: 6 weeks
Hardening Phase: Plants were ready for out planting in early July. No hardening necessary for mid-summer planting.
References: Weakley, A. S., and the Southeastern Flora Team, Flora of the Southern and Mid-Atlantic States. Retrieved from
https://fsus.ncbg.unc.edu/main.php?pg=show-taxon.php&plantname=Pycnanthemum+curvipes
U.S.D.A. Natural Resources Conservation Service. (n.d.) Pycnanthemum curvipes. Retrieved from https://plants.usda.gov/home/plantProfile?symbol=PYCU

Citation:

Zuidervliet, Claire; Pyne, Stephen. 2023. Propagation protocol for production of Container (plug) Pycnanthemum curvipes Plants Wild; Mt. Cuba Center Hockessin, Delaware. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2025/04/20). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.