Upright Conifers for the Garden
How to Choose and Use Columnar Needleleaf Trees in the Landscape
Sep 11, 2009
Conifers are interesting plants. They all have cones, though female junipers, yews and plum-yews disguise theirs to resemble berry-like fruit. And they're usually needle-leaf evergreens, though some, like the larch, dawn redwood and bald cypress, lose their needles in the winter.
They come in all shapes and sizes, from small, rounded dwarfs that might take 30 years to reach 2', to the majestic coastal redwood, which can grow to over 350'.
And they're prolific, with over 500 species spread throughout the world.
The American Conifer Society categorizes conifers in four distinct sizes: miniature, dwarf, intermediate, and large. But they acknowledge that growing conditions within cultures, climates and regions play a part in the ultimate size a particular plant may reach.
Conifers with an upright habit may range from miniature to large. These plants create an extremely vertical statement and include naturally occurring fastigiate, columnar, narrow pyramids or narrow conical types.
Upright Conifer Maintenance
Plant health can be promoted by periodic select pruning. Pruning for aesthetic purposes is possible, but extreme pruning (to force a more rounded plant, say, to conform to a columnar or fastigiate form) is not recommended, as it results in an artificial appearance. It can also weaken the conifer's limbs and joints.
Before pruning, gardeners should know how their particular plant puts on new growth. Various conifer species add growth in entirely different ways. Pruning without forethought can ruin the plant's form.
Most upright conifers are easy to grow and need little pruning to maintain their shapes. Insect pests are rare, though hemlocks and spruces tend to attract mites in dry, hot locations. And where hemlocks grow, the hemlock adelgid could also be a problem.
In snow country upright conifers, especially extremely vertical species, may be subject to damage from snow loads due to the extreme angle of their branches.
Selected Upright Conifers for the Landscape and Garden
Large Upright Conifers:
- Cupressocyparis leylandii 'Haggenston Grey' - good screen; vigorous; gray-green; 20' x 90'; zone 6-9
- Cupressocyparis leylandii 'Castle Wellen' - bronze yellow foilage; 15' x 80'; zone 6-9
- Cupressocyparis leylandii 'Harlequin' - varigated; grows fast; grey-green foliage with patches of ivory white; zone 6-9
- Picea omorika (Serbian Spruce) - narrowly conical; dark green; 10' x 60'; zone 4-7
Intermediate Upright Conifers:
- Calocedrus decurrens (Incense Cedar) - aromatic, fan-like foliage; good accent; 10' x 45'; zone 5-8
- Chamaecyparis lawsoniana 'Green Pillar' - bright green; aromatic; tinged with gold in spring; 8' x 50'; zone 5-9
- Chamaecyparis lawsoniana 'Columnaris' - narrow upright, good specimen tree; blue-gray; 5' x 30' zone 5-9
- Cupressus macrocarpa 'Goldcrest' - fast growth; gold-yellow leaves (foilage useful in flower arrangements); 12' x 30'; zone 7-11
Miniature and Dwarf Upright Conifers:
- Juniperus chinensis 'Robust Green' - slow grower (3"/yr.); green foliage; 3' x 10'; zone 5-9
- Pinus sylvestris 'Fastigiata' - obelisk shape; flaky, red-brown bark; blue-green foliage; 4' x 20'; zone 2-7
- Juniperus chinensis 'Obelisk' - irregular columnar; dark green; likes hot, dry sites; 3' x 13'; zone 3-9
- Juniperus communis 'Hibernica' (Irish Juniper) - needs sun; gray; 2' x 6'; zone 2-6
- Juniperus virginiana 'Sky Rocket' - pencil shaped form; bluish foliage; width varies depending on where grown; zone 3-9
Upright Conifer Survival Tips
To keep upright conifers happy and healthy, select plants suited to the climate and adapted to the region.
- Seasonal Extremes - Temperature varies throughout the year, so think not only cold hardiness, but heat tolerance.
- Water - how much moisture is available at different times of the year. Drought tolerance is important in areas of periodic rain deficit.
- Climate - broadly defined as "the elements". Includes yearly rainfall, temperature fluctuations, length of daylight, and area soil types.
- Microclimate - conditions in a specific place, like a garden, make up that site's microclimate, which may differ somewhat from the regional climate as a whole
- Soils - while most conifers can live perfectly well in any soil, firs don't take to poorly drained clay soils. County Extension offices can test soils for conifer compatibility. Pines like acidic soils, around a 3.5 to 4.0 pH. Junipers like a more neutral soil type of 6.0 to 7.0 pH.
- Sunlight - Intense sunlight can damage some species of conifers. Choose plants for specific light conditions, whether full sun, part shade, or full shade.
- Air Circulation - some conifers hold up well to storm winds and are used as wind buffers. Others don't.
Landscape Use of Upright Conifers
The varying shapes, habits and varied colors of upright conifers make them great accents. Use as specimen plants for year-round interest, to provide scale next to the corner of a building, or where a vertical statement is needed.
They work best in formal settings, and can be used alone or in groups of 3 to 5 plants. Use them as foils in mixed bed plantings, or in beds of contrasting form and color with other conifers. They provide year-round color, and add to the "bones" of the garden.
With the many varieties of upright conifers available, it's easy to find one to fit a particular situation. And with more varieties being developed every day, there's never been a better time to try an upright conifer in the garden.
Sources:
- The Rosebay (website of the Am. Rhododendron Society), article entitled "Garden Conifers", by Les Wyman
- Brooklin Botanic Garden website, article entitled "Selecting Conifers for Your Garden", by Kim Tripp
- James Nursery Company website, article entitled "Columnar Conifers"
- Encyclopedia of Plants and Flowers, The American Horticultural Society; 2002 DK Publishing
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