Tuesday, January 15, 2019

Japanese Umbrella Pine

30-year old Specimen at NC Arboretum in Asheville
Japanese Umbrella Pine (Sciadopitys verticillata) is an evergreen (USDA hardiness zones 5b -9). It is not actually a pine and is more closely related to yew (Taxus).  

Historically, umbrella pines date back to the dinosaur age. This mid-sized landscape tree possesses several fine attributes: shiny leaves are arranged in whorls like the spokes of an umbrella; peeling, reddish brown bark and a conical habit.

To conifer collectors, umbrella pine is the premium prize for any private collection. A young tree may require training to develop a strong central leader. Dwarf cultivars (see below)  grow slowly, only 4-5 inches yearly.

Umbrella Pine prefers a moist, organically rich, well-drained, moderately acidic soil. Feed with a slow release organic fertilizer in early spring. Maintain a 2-3 inches layer of an organic mulch around the tree base. In the mid-South (zones 6 -7), the tree prefers one-half to full-day sunlight. Further south,  morning sunlight is preferred. Pruning needs are rare, mostly to maintain the tree's pyramidal form and to remove a broken limb or two in late winter. Disease and insect problems are rare.

In the early years umbrella pine is a slow grower. Eventually, it reaches 30 to 40 feet in height and 20 feet in spread. Well cared for tree forms may attain 70 feet or more in height. This unique conifer possesses stiff needles arranged in whorls resembling an upside-down umbrella. Branches often will withstand heavy snow and ice loads.

The Umbrella Pine is an evergreen prized for its striking foliage and superior pyramidal form. Needles rarely go off color in winter. Select forms are available at specialty conifer nurseries.
Here are four dwarf forms for small gardens:
'Aurea' - yellow needle foliage
‘Gruene Kugel’ - from Germany with a rounded habit when young, slowly develop into a small compact tree with glossy deep green foliage year-round.
‘Joe Kozey’ grows tall and exceptionally narrow at 20 feet high and only 6 feet wide; slow-growing, spire-like habit.
'Picola' - broad growing, 2- inch long dark green needles; ultra-dwarf selection 16- 20 inches tall after 10 years; rock garden plant.

Tuesday, January 1, 2019

Dwarf Forms Of Elkhorn Cedar (Thujopsis)


Elkhorn cedar (Thujopsis dolobrata) is a slow to moderate growing evergreen shrub or tree. It is also called Hiba or false arborvitae and deerhorn cedar, referring to the shape of its scale-like leaves. It is rarely grown in U.S. gardens (USDA hardiness zones 5-7).

Thujopsis 'Aurea'
This native of Japan and China has a pyramidal growth habit and beautiful dense foliage similar to arbovitae (Thuja spp.). Mature trees may reach 50 -100 feet in height in the Japanese woodlands.  

The scale-like bright or dark green leaves are arranged in flattened sprays with white markings beneath.  Its reddish-brown peeling bark adds to the plant's appeal.  Small 3/4 inch cones provide little ornamental value. 

False arborvitae grows best on a moist well-drained site in full sun or bright shade . Occasional watering is recommended in severe summer/fall dry periods. False arborvitae needs to be sheltered from dry winter winds.

Winter foliage color may vary by location and cultivar planted. Here in the Southern Appalachian Region (USDA zones 6 and 7), winter foliage takes on a muted olive-green tone.
Two dwarf clones are:
  • 'Aurea' - a dense shrub with golden yellow foliage; grow in light shade.
  • ‘Nana’ - a slow growing, dwarf mounding form with good plant symmetry. Its wintry foliage takes on a silvery tint.
A 10-year old 'Aurea' or 'Nana' thujopsis grows 3 to 4 feet tall and 5 to 6 feet wide. 
False arborvitae is hard to find in the nursery trade, but are available thru e-commerce specialty nurseries.