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Using Conifers in Your Garden

by by Kim Tripp

Conifers aren't just stereotypical little green pyramids or looming forest trees. There is enough variation in shape, size, foliage color and texture, bark characteristics and ornamental cone types to whet any gardener's appetite. When looking for conifers to provide your garden with changing seasonal interest, consider the following ornamental qualities.

Color

From the pink cones of the larch, to the blue foliage of the aptly named Colorado blue spruce, to the silver bark of the lacebark pine, the range of color in conifer cones, bark and foliage is vast. Emerald green arborvitae sprays, the coppery fall foliage of the dawn redwood and the plum-colored winter foliage of the Siberian juniper are just a few examples of extraordinary conifer coloration.

Both foliage and cones provide the primary color interest, with bark also playing a role. Cultivars of otherwise green species have been selected for distinctive blue or gold leaves and needles. Variegated selections also abound, some with showy splashes throughout the foliage, and others with subtle frostings on only the tips of the needles.

The feathery foliage of the deciduous golden larch (Pseudolarix amabilis) turns a brilliant bronze-gold in the fall.

The foliage of many conifers changes color throughout the seasons. Some cultivars have been selected for contrasting new spring growth while others, like Pinus strobus 'Hillside Winter Gold', change color with the advent of cold weather and then return to a quieter green as the weather warms for the growing season. Deciduous conifers that develop fall colors before their needles drop—including shades of gold, bronze, bright yellow or cinnamon—add dimension to the range of foliage colors. The striking Pseudolarix, for example, turns a brilliant bronze-gold in the autumn months.

Seasonal changes in foliage color on evergreen plants are a function of temperature changes, while color change in fall foliage of deciduous conifers is analogous to that of other deciduous plants.

Cone colors offer still another range of ornamental possibilities. As cones develop, they may go through some very showy color stages, from bright violet in Korean firs to the shocking pink in true larches. These color changes are part of the cones' natural maturation processes.

A number of conifers have seeds or fleshy cones that look like brightly colored berries. For example, the red arils—the fleshy, berry-like covering on seeds of yews—sparkle among the foliage like crimson jewels. Conifer barks can also be quite striking, with colors ranging from the cream-gray-green puzzle of young lacebark pine to the bright orange of mature Scots pine. Ultimately, color is a personal and subjective choice. When selecting conifers for your garden, consider whether you want a riot of color or a more subdued color scheme with conifers of similar colors.

Texture

Texture is a function of bark, foliage and the arrangement of branches. Evergreen selections offer a different kind of texture than deciduous conifers, whose foliage changes dramatically throughout the seasons—and even disappears altogether in winter to reveal the architecture and color of branches and trunk. The relatively broad, flattened needles of the Japanese umbrella pine offer bolder texture than the fine feathery needles of the eastern white pine, while the dark, platey bark of mature Japanese black pine has a vastly different texture from that of the lightly peeling, red-brown bark and deeply fluted trunk of dawn redwood.

The textural combinations you choose for your garden will reflect its unique style. Do you want a uniform sight-line of hedges down an allŽe or a more varied and natural-looking selection of textures? As with color, this is a matter of taste.

Habit

Plant habit refers to both overall shape and size, as well as to the arrangement and display of branches along the trunk. For example, the overall outline of pendulous Pinus strobus 'Pendula' is that of a rounded pyramid with weeping branches. The narrowly columnar Juniperus chinensis 'Spartan' has the general outline of a broad pillar. Slow-growing and ground-hugging Juniperus horizontalis 'Mother Lode' is shaped like a dwarf pancake.

The habit of most coniferous trees changes over their lifetime. Younger plants tend to have more upright, conical habits that eventually spread and open with age. But this "rule" has so many exceptions that it is only a very general one at best.

The range of conifer shapes and sizes includes everything from tiny dwarf bun selections like the Chamaecyparis obtusa 'Elf', which after many decades of growth is still the the size of a softball, to the towering coastal redwoods of California—and everything in between. When choosing conifers for your garden, be sure to look beyond the formal conical habit so often associated with sheared Christmas trees and overused Colorado blue spruce.

Mature Size

Every gardener wants to know how big a plant will grow and how fast it will get there. Homeowners want plants that will grow rapidly for a few years, reach some pre-determined size and shape and then remain static and unchanging until death. But that is not the way plants work. They reach a general size range at maturity that can be heavily influenced by the growing environment, but their ultimate size is only a guess.

In general, growth rates tend to be more rapid in young plants than in their older counterparts. Although there is some slowing with age, growth does not cease. Different plants do mature in different height classes and ranges but growth rate and ultimate development is a function of many factors in addition to the plant's basic identity, including climate, fertility, water availability, light intensity, propagation method and pruning practices.

What, exactly, do "mature height" or "ultimate size" mean? Plant height and spread at 5 years, 10 years, 50 years, 150 years? While the same plant grown in Minnesota and South Carolina may be perfectly hardy in both regions, it likely will exhibit very different growth rates in the warm Southeast than in the colder, northern Midwest. Entries in the Encyclopedia of Conifers, page 39, include estimates of average landscape size for plants grown in a reasonably non-stressful landscape environment; comments on regional variability and unusual growth rates are included where appropriate.