December 2007
Growing Deciduous Conifers
Leonard J. Buck Garden, Far Hills, NJ
Winter solstice is around the corner marking the beginning of winter and the end to another successful year of gardening.
Your spring bulbs have been planted, you fertilized your lawn, coiled your hoses and mulched your garden beds, now it's time to relax, or is it? This festive month keeps us very busy and before you know it we're singing Auld Lang Syne. Somewhere in between adding decorative touches to your front lawn, buying garden-related gifts for family and friends, visit the Leonard J. Buck Garden and enjoy this winter wonderland before it melts away.
During December both the dawn redwood and bald cypress give up their masquerade as evergreens and surrender their leaves. During the summer months these trees have the distinctive narrow needled leaves we identify with evergreens of spruce, pines, and yews. In the fall their needles turn an autumnal rusty brown before they drop to the ground in winter.
Dawn Redwood, Metasequoia glyptostroboides, has been around for some 100 million years. Fossil records show dawn redwood was once native to western North America, Asia, and northern Europe. As the climate changed, the trees were thought to be extinct for millions of years until 1941 when a grove of these trees was discovered growing in remote parts of China. In 1947 the Arnold Arboretum sponsored an expedition to China to collect seed from this thought-to-be-extinct, prehistoric, tree. The dawn redwoods growing in Buck Garden are a result of that seed expedition. Through years of sharing seed and propagating with other arboreta the dawn redwood returned to North America and became available in the nursery trade.
Dawn redwoods are very fast growers. They can reach 50 feet tall in 15 to 20 years, and have the potential to grow as high as 120 feet with a girth of more than 12 feet. They have beautiful, shredding, orange bark and distinctive arm pits where the branches attach to the main trunk. The mature, dawn redwood growing behind our Visitors Center stands over 100 feet tall with a trunk girth over 12 feet. Dawn redwoods perform best in moist, deep, well-drained, slightly acidic soils. They have few insect and disease problems, but Japanese beetles will eat the leaves. The longevity is proof that the dawn redwood must be adaptable and they seldom need pruning due to their neat pyramidal habit. Whether you grow dawn redwood as a single ornamental tree or in groups to line driveways or streets it's a lovely deciduous evergreen.
Bald Cypress, Taxodium distichum, sometimes referred to as “swamp cypress" looks like an evergreen but is another deciduous tree, losing their foliage every fall after it turns a glowing orange. Their deciduous character is the reason for the common name, bald cypress. They are native to moist areas of North America and are best known for their characteristic knobby knees which project from the root system upward above water level. It is shown that the knees are not necessary for gaseous exchange.
Because it is resistant to wood-rotting fungi, Bald Cypress is valued as softwood lumber for shingles, trim, and especially for greenhouse benches and racks. Bald cypress forms dense forests in the southeastern swamplands and is a common tree of the Everglades. We associate them with water even though they are equally at home in parks, along streets and in large back yards. They tolerate dry periods just fine and their buttressed base gives them tremendous tolerance to withstand high winds. When planted on dry land they usually do not produce knees.
Bald cypress are distinctly pyramidal, their annual growth rate is 12 to 18 inches and can reach 70-80 feet tall and 20-30 feet wide.
They grow best on moist to wet areas with acidic soil. They can develop iron deficiency which causes the leaves to turn yellow in high pH soils. Twig blight, a weak pathogen usually present on dead or dying tissue, has been reported on landscape plants. When the tree is stressed the fungus can kill branch tips, which can be pruned off. Do not let dead or diseased branches remain on the tree. A grouping of bald cypress grows in the Kennel Field alongside other plants of wet soil.
These two striking, deciduous conifers, dawn redwood and bald cypress, are unrivaled for large spaces in a park or large yard. They are stately trees that can stand alone or be grouped together. Either way they provide a spectacular effect in the winter garden.
This month take a reprieve from your holiday schedule and discover the contrasting shapes, textures and silhouettes of these deciduous evergreens at the Leonard J. Buck Garden.
- Tricia Scibilia, interpretive gardener
**All photos by Tricia Scibilia unless credited otherwise
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