Conifers are plants that “set” seed-containing cones to reproduce, in contrast to plants that flower to form seed containers. If you equate “conifers” with “evergreens,” think again! Although many conifers are evergreen, the aptly named bald cypress (Taxodium distichum) is one example of a deciduous conifer that loses its needles in winter. Mountain laurel (Kalmia latifolia) is one of many evergreens that are not conifers. This is one reason correct identification of your plants is so important when you seek advice about your landscape!
Evergreen conifers commonly grown in our landscapes include Carolina hemlock (Tsuga caroliniana), Norway spruce (Picea abies), white pine (Pinus strobus), Eastern red cedar (Juniperus virginiana), American arborvitae (Thuja occidentalis), blue rug juniper (Juniperus horizontalis), hinoki falsecypress (Chamaecyparis obtusa), English yew (Taxus baccata), and Fraser fir (Abies fraseri).
Conifers contain examples of the world’s oldest trees, such as the bristlecone pines (Pinus longaeva). These grow in the desert mountains of California and Nevada and are estimated to be over 5,000 years old. Many of the world’s biggest trees are also conifers. These include the giant sequoias (Sequoiadendron giganteum) found in the Sierra Nevada Mountains of California that can reach heights of 95 meters (312 feet), and the coast redwoods (Sequoia sempervirens) growing along the California coast that can reach heights of 110 meters (361 feet).
Before you make any decisions about pruning, consider the natural growth habit and landscape value of the plant. Most conifers require only minimal pruning and will perform well in your landscape without your intervention. That said, do not hesitate to get out your pruning tools when you see dead or diseased branches. Leaving these on a tree or shrub provides a route for disease pathogens and insects to enter and they should be promptly removed. Many gardeners choose conifers for formal or informal hedges. When you shear any conifer hedge, remember to leave the bottom of the plants a bit wider than the tops to get light to the lower limbs, keeping them lush and green.
Most conifers are “self-limbing.” They naturally lose their lower branches as they mature. Have you walked through a mature, healthy pine forest? You’ll see hardly any limbs within 3 meters (about 10 feet) of the ground. This is not the pruning work of some forest gnome! The trees shed their lower limbs on their own as they grow taller. This is an example of knowing the natural growth habit of your landscape plants when making pruning decisions.
Different conifer species bud differently and therefore require different approaches to pruning.
- Pines have buds only at the tip of the current season’s growth, not on the stems. So, prune pines in the spring when you can cut or pinch the soft new growth—called “candles”—before the needles are fully elongated. Buds will develop from needle sheaths below the cut.
- Firs, cedars, and spruce also bud along the current season’s growth, but on the stems. Prune these species back to the bud before the current year’s growth hardens.
- Yews and hemlocks bud on both old and new wood. Their buds develop into twigs when you cut the wood above. Pruning in the spring, just before the new growth begins, allows new growth to cover the pruning cuts.
- Juniper and arborvitae have buds present only where there are green leaves. Note that prolonged use of electric hedge shears on juniper and arborvitae hedges will result in a very small veneer of needles just on the outer surface of the plants. If part of a continually sheared plant dies or is cut back too far, there are no inner leaf buds to develop, and you will be left with a “hole” in your hedge.
Remember, the Buncombe County Extension Master Gardener HelpLine and Information Tables are important sources of information about identifying and maintaining garden plants, including conifers.
Article written by Bob Wardwell, Extension Master GardenerSM Volunteer.
Selecting Landscape Plants: Conifers
by Virginia Cooperative Extension
by American Conifer Society
Online database provides information and photographs about conifers, including pruning, care, and varieties.