November Plant of the Month - Dwarf Japanese Cedars

 

A beautiful species of conifer remains relatively unexploited in southeastern gardens, and offers much landscape appeal. Japanese cedar (Cryptomeria japonica) is not a cedar at all but is in the same family as Bald Cypress (Taxodium), Taxodiaceae. Cryptomeria is an extremely variable conifer that includes well over 100 cultivars available in the US. They can range in size from 6-inch dwarf forms to 80-foot tall trees in the wild. In cultivation, full size specimens of the species can reach 50- to 60-feet tall. All Japanese cedars can be pruned to keep a more compact form. Pruning is best done just before new growth begins in the spring, but proper cultivar selection can eliminate the need for pruning.

The evergreen leaves are made up of spirally arranged needle-like leaves. The foliage can range in color from bright to dark green, bluish green, golden yellow and some can have almost pure white variegation. During the winter, bronzy tones can develop, especially when exposed to winter wind. Some cultivars produce an overabundance of male cones that can take away from the plant's overall look. Japanese cedars require little care and are easy to grow. They grow well with average moisture in well drained soil in full sun to light shade. Some of the variegated forms benefit from afternoon shade, especially in the hot humid summers of Tennessee. Japanese cedars are best grown in zones 6 to 8.

Large forms like the cultivars 'Ben Franklin', 'Winter Mint' and 'Yoshino' make good screening plants that are medium to fast growing and demand a fair amount of room in the garden. For people with limited space, there are many great dwarf forms. Three of our favorite cultivars in the gardens in Jackson are 'Globosa Nana', 'Black Dragon' and 'Magic Dragon'.

'Globosa Nana' has been a favorite cultivar since I first saw it about 8 years ago. It forms a billowy meat ball shape without pruning. It is a wonderful substitute for boxwoods, dwarf yaupon and Japanese hollies and other common foundation plants that are often pruned into balls. It is very soft to the touch and is one of those plants you just want to pet. In 10 years, it can reach 4 x 4 feet in size. A 30-yearold specimen at the National Arboretum in Washington, D.C., is 8 x 8 foot.

'Black Dragon' has dense foliage and spaced branches. The foliage is extremely dark green, and the plant makes a strongly sculptural statement. Unfortunately, there are a couple of forms on the market with the same name, so it is difficult to predict eventual size. The form most commonly found will reach 10 to 12 feet tall, and 3 to 4 feet wide. 'Black Dragon' produces male and female cones but not in an overabundance. Average growth rate is 6 to 12 inches a year.

'Gyokuryu' is a multi-leader vigorous cultivar that forms a dense broad pyramid with bright green foliage. It grows to 8 to 10 feet tall and 4 to 6 feet wide and produces few cones. It sometimes sold under the common name Magic Dragon should be correctly called 'Gyokuryu'.

These small forms are winners even in gardens with limited space. They lend themselves to multiple uses and with the variety of form and shapes you're sure to find one that suits your design. Be prepared for your newest plant addiction - Cryptomerias.

Jason Reeves is an Ornamental Horticulture Research Associate with the UT AgResearch and Education Center in Jackson, Tennessee. He creates the various seasonal horticultural displays, conducts research on herbaceous and woody ornamentals, and supports various educational programs. The UT Gardens in Jackson and Knoxville are both open to the public. See http://utgardens.tennessee.edu/ for more information.

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Contact:
Jason Reeves, (731) 424-1643