Penstemon digitalis: Foxglove Beardtongue

Latin name: Penstemon digitalis
Common name: Foxglove Beardtongue, Smooth White Beardtongue ¹⁰
Flowers: White with purple lines in throat, one inch long flowers, and blooms for three months May – July¹⁰
Fruit: Tan color, inconspicuous¹⁰
Height & Width: 3ft -5ft tall, 1 1/2-2ft wide ^10,12,19 
Type: Herbaceous perennial^10,12,19
Habit: Herb^10,16 upright¹⁸
Wetland indicator category**: FAC¹⁷
Texture: Fine¹⁶
Growth rate: Fast¹⁹
Light: Full sun, part shade^10,19
Moisture: Dry, moist, wet¹⁰
Soil*: Fertile, well drained loams, clay loam, sand, soil pH 5.5 – 7.0^10,16 can be grown in slightly alkaline and alkaline soils as well¹⁹
Zones: 3 to 8¹²
Origin: Native to the lower 48 states¹⁶
Ecosystem benefits: Attracts birds, hummingbirds, butterflies and provides nectar^10,12,19

Features: The flowers of this plant are both aesthetically pleasing and beneficial because they attract butterflies, bees, and hummingbirds. It is drought tolerant but also performs well in wet soils, making it an ideal plant for a rain garden¹². Although the plant is short lived the showy foliage it provides has aesthetic value for the viewers²⁰.

Siting: The plant is a great plant for places in yard that are clay loam soil and have poor drainage. This plant does well in a rain garden but will also tolerate dry shade¹⁰. In South Carolina it can be grown in the Upstate, Midlands, and Coast¹⁹.

Care: Plant crown at soil level¹⁸. At planting, water the roots and surrounding area slowly and deeply. Keep soil moist until plant is established, then apply enough water to thoroughly moisten the root zone when the soil is dry or during drought. Modify water recommendations to reflect site drainage and rainfall. Apply 3” of mulch over the planted area. Do not allow mulch to touch the plant stems¹⁸. For a cleaner appearance cut the bloom stalks once they have turned brown. Short lived and will need to be reseeded intermittently¹⁰.

Pests: Foxglove is tolerant of deer, and relatively pest resistant if culture preferences are met¹².

This plant does not appear on the following invasive plant lists on (2/24/2019):

• USDA SC Invasive Plant Species Web site at http://www.invasivespeciesinfo.gov/plants/main.shtml
• SC Exotic Plant Pest Council Web site at http://www.se-eppc.org/southcarolina/

Author: Cy Gettliffe

Image source: http://www.missouribotanicalgarden.org/PlantFinder/FullImageDisplay.aspx?documentid=2511

Sources:

1. Armitage, A. (2001). Armitage’s manual of annuals, biennials, and half-hardy perennials. Portland, OR: Timber Press.
2. Armitage, A. (2006). Armitage’s native plants for North American gardens. Portland, Oregon: Timber Press.
3. Armitage, A. (2008). Herbaceous perennial plants: A treatise on their identification, culture, and garden attributes. Athens, GA: University of Geogia.
4. Clemson Cooperative Extension Home and Garden Information Center.(2011). Flowers fact sheets. Retrieved from https://hgic.clemson.edu/category/flowers/
5. Clemson Cooperative Extension Home and Garden Information Center.(2011). Groundcovers & vines fact sheets. Retrieved from https://hgic.clemson.edu/category/groundcovers/
6. Clemson Cooperative Extension Home and Garden Information Center.(2011). Trees. Retrieved from https://hgic.clemson.edu/category/trees/
7. Clemson Cooperative Extension Home and Garden Information Center.(2011). Shrubs. Retrieved from https://hgic.clemson.edu/category/shrubs/
8. Dirr, M. A. (2009). Manual of woody landscape plants. Champaign, IL: Stipes Publishing.
9. Gilman, E. F. (1997). Trees for urban and suburban landscapes. Albany, NY: Delmar Publishers.
10. Lady Bird Johnson Wildflower Center University of Texas at Austin. (2012). Native plant information network. Retrieved from http://www.wildflower.org/explore/
11. McMillan, P., Plant taxonomist Clemson University, personal communication.
12. Missouri Botanical Garden Kemper Center for Home Gardening. Plant finder. Retrieved from http://www.mobot.org/gardeninghelp/plantfinder/Alpha.asp
13. North Carolina State University (2005). Plant fact sheets. Retrieved from http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/index.html
14. Strother, E. V., Ham, D. L., Gilland, L. (2003) Urban tree species guide: Choosing the right tree for the right place.  Columbia, SC: South Carolina Forestry Commission.
15. University of Florida, IFAS Extension. (2011). Southern trees fact sheet. Retrieved from http://edis.ifas.ufl.edu/department_envhort-trees
16. USDA. Plant profile. (n/d).Retrieved from http://plants.usda.gov/java/
17. USDA. Plant wetland indicator status. (n/d). Retrieved from http://plants.usda.gov/wetland.html
18. Vincent, E., Environmental horticulturist Clemson University, personal communication.
19. Clemson Extension. Carolina Yards Plant Database. Retrieved from https://www.clemson.edu/extension/carolinayards/plant-database/index.htm
20. Gettliffe, C., Junior Student of Horticultural Clemson University, personal knowledge.

*Soil pH is determined using a professional soil test. Contact your Clemson University County Extension service for assistance www.clemson.edu/extension/. Click on “local offices”.

**2012 Plant Wetland Indicator categories (quantitative derived) http://plants.usda.gov/wetinfo.html

Indicator Code	Indicator Status	Comment
OBL	Obligate Wetland	Almost always is a hydrophyte, rarely in uplands
FACW	Facultative Wetland	Usually is a hydrophyte but occasionally found in uplands
FAC	Facultative	Commonly occurs as either a hydrophyte or non-hydrophyte
FACU	Facultative Upland	Occasionally is a hydrophyte but usually occurs in uplands
UPL	Obligate Upland	Rarely is a hydrophyte, almost always in uplands