ENH-705

Quercus glauca: Blue Japanese Oak1 Edward F. Gilman and Dennis G. Watson2

Introduction Pronunciation: KWERK-us GLAW-kuh Common name(s): Blue Japanese , ring-cupped oak At first glance, this would hardly be thought to be an Family: oak. Creating a very formal, dense, round or oval shade, USDA hardiness zones: 8A through 9B (Fig. 2) evergreen blue Japanese oak grows slowly to 25 to 40 feet Origin: not native to North America in height with a spread of 25 to 35 feet. The new growth Invasive potential: little invasive potential is often bronze- or purple-tinted, and develops into shiny, Uses: street without sidewalk; parking lot island 100-200 dark green, 2.5- to 5.5-inch-long by 1- to 2.5-inch-wide, sq ft; shade; parking lot island > 200 sq ft; lawn 3-4 feet leathery . It is a very attractive tree suited for many wide; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; highway uses. median Availability: not native to North America

Figure 1. Middle-aged Quercus glauca: blue Japanese oak Figure 2. Range Credits: Ed Gilman, UF/IFAS Description General Information Height: 25 to 40 feet Spread: 25 to 35 feet Scientific name:Quercus glauca Crown uniformity: symmetrical

1. This document is ENH-705, one of a series of the Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date November 1993. Revised December 2006. Reviewed May 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.

2. Edward F. Gilman, professor, Environmental Horticulture Department; Dennis G. Watson, former associate professor, Agricultural Engineering Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension. Crown shape: round, oval Soil tolerances: clay; sand; loam; acidic; occasionally wet; Crown density: dense well-drained Growth rate: slow Drought tolerance: high Texture: medium Aerosol salt tolerance: unknown

Foliage Other arrangement: alternate (Fig. 3) Roots: not a problem Leaf type: simple Winter interest: no Leaf margin: serrate, dentate Outstanding tree: no Leaf shape: oblong, obovate, elliptic (oval) Ozone sensitivity: unknown Leaf venation: pinnate Verticillium wilt susceptibility: resistant Leaf type and persistence: broadleaf evergreen, evergreen Pest resistance: resistant to pests/diseases Leaf blade length: 2 to 4 inches, 4 to 8 inches Leaf color: green Use and Management Fall color: no color change Blue Japanese oak has been used as a street and parking Fall characteristic: not showy lot tree in parts of the southeast for a number of years. Was used in USDA hardiness zone 7b until the 1983 freeze which reduced large to a collection of sprouts. It ap- pears to be tolerant of drought and poor, clay soil including those which are poorly-drained and grows well in tight soil spaces. Its tight crown lends a formal feel to the landscape.

Many upright trunks and branches originate from one Figure 3. Foliage point on the trunk without initial training, and this struc- ture could lead to a weak tree. Following initial training and pruning to develop a central leader and well-spaced branches, little care should be needed to maintain this tree. Flower color: brown It should be grown and planted more in urban areas in the Flower characteristics: not showy South.

Fruit Blue Japanese oak should be grown in full sun. It is tolerant shape: oval, round of a wide range of soils, including heavy clay soils. Fruit length: .5 to 1 inch Fruit covering: dry or hard Propagation is by seed. Fruit color: brown Fruit characteristics: does not attract wildlife; not showy; Pests and Diseases fruit/leaves a litter problem There is a large number of potential problems on , but none of major concern. Trunk and Branches Trunk/bark/branches: branches droop; not showy; typi- cally one trunk; thorns Pruning requirement: needed for strong structure Breakage: susceptible to breakage Current year twig color: green, brown Current year twig thickness: thick Wood specific gravity:unknown

Culture Light requirement: full sun

Quercus glauca: Blue Japanese Oak 2