Evergreen trees maintain their foliage throughout the year, providing continuous color and structure to the landscape. They are broadly categorized into two types: conifers (pines, spruces, firs) which have needle-like leaves and bear cones, and broadleaf evergreens (holly, rhododendrons) which possess flat, waxy leaves. Retaining their leaves allows evergreens to photosynthesize year-round, making them invaluable for privacy screens, windbreaks, and winter ornamentation.
Successful Planting and Initial Establishment
Choosing the correct planting location is the first step toward a healthy evergreen, as most varieties thrive in well-drained soil and full sun exposure. Before planting, consider the tree’s mature size and avoid spots too close to structures or power lines, ensuring the tree has adequate room to grow. Soil preparation should focus on improving drainage, especially in heavy clay, and the addition of organic matter can help establish a looser soil environment for new roots.
When digging the hole, aim for a width two to three times that of the root ball, but only as deep as the root ball itself. A frequent mistake is planting the tree too deep, so the top of the root ball should sit level with or slightly above the surrounding soil surface to prevent waterlogging and root rot. For balled-and-burlapped trees, remove all twine, wire, and as much burlap as possible from the top and sides of the root ball before backfilling the hole.
After placing the tree and gently tamping the soil to eliminate air pockets, deep watering is immediately necessary to settle the soil around the roots. A layer of organic mulch, such as wood chips or shredded bark, should be applied in a 2- to 4-inch layer around the tree, extending out to the drip line. Keep the mulch several inches away from the trunk itself to prevent moisture from causing rot or attracting pests.
Routine Watering and Feeding Requirements
Newly planted evergreens require consistent moisture to regenerate their root systems, needing up to two inches of water per week for the first few growing seasons. For established trees, the goal is deep, infrequent watering that moistens the soil to a depth of 8 to 12 inches, encouraging deep root growth rather than shallow surface roots. Always check the soil moisture by hand four to six inches down; if the soil feels dry at that depth, it is time to water.
Watering needs change seasonally, requiring increased frequency during hot summer months and dry periods. Evergreens benefit from a thorough deep watering in the late fall, before the ground freezes, to hydrate the foliage and roots for the winter months. This pre-winter hydration helps prevent desiccation, where needles lose moisture faster than frozen roots can replenish it.
Evergreens require minimal fertilizer, and newly planted trees should not be fertilized in their first year to avoid burning tender new roots. For established trees, apply a balanced, slow-release fertilizer formulated for evergreens in the early spring as new growth begins. Avoid fertilizing after mid-summer, as late-season feeding stimulates new growth that will not have time to harden off before winter.
Specific Evergreen Pruning Techniques
Pruning evergreens maintains shape, removes damaged wood, and manages density, with techniques varying by tree type. Conifers, such as pines and spruces, do not sprout new growth from old wood, so cuts must only be made where green needles are still present, cutting back to a lateral branch or bud. Dead, diseased, or broken branches can be removed at any time of year and should be cut cleanly back to the branch collar for proper wound closure.
Pines and other conifers that produce “candles,” which are the soft, upright new growth shoots in the spring, are pruned using a technique called candling or pinching. This is done in late spring or early summer, when the candle is fully elongated but before the needles have completely emerged and hardened. To promote denser growth and control the tree’s overall size, the candle is shortened by pinching or cutting off one-half to two-thirds of its length.
Broadleaf evergreens, like yews and hollies, are tolerant of aggressive pruning and can be sheared or cut back into older wood to maintain a formal shape. For a natural look, use selective thinning cuts to reduce density and encourage light penetration. The best time for major shaping or shearing is late winter or early spring, just before the flush of new growth.
Managing Common Pests and Environmental Threats
Evergreens are susceptible to pests like spruce spider mites and pine needle scale, which are sap-sucking insects causing stippling, yellowing, and premature needle drop. Spruce spider mites are cool-season pests, with damage seen in spring and fall, confirmed by fine webbing on the needles. Pine needle scale appears as small, white, armored bumps on the needles, sometimes making the tree look frosted or silvery.
Fungal issues like needle cast disease affect evergreens, causing older needles inside the canopy to turn brown and drop prematurely. Proper air circulation, achieved through selective pruning and avoiding dense planting, is a preventative measure against fungal development. Inspecting trees regularly for early signs of discoloration or insect activity allows for prompt treatment with dormant oils or specific pesticides when populations are low.
Environmental stressors, particularly in winter, pose a significant threat, most notably winter burn, caused by sun, wind, and frozen soil. The foliage loses moisture through transpiration, but the frozen ground prevents roots from taking up replacement water, leading to desiccation and browning.
Protecting vulnerable evergreens with burlap screens or windbreaks on the windward side can block harsh, drying winds and direct sun. Applying anti-desiccant sprays to the foliage in late fall creates a thin, waxy layer that temporarily reduces moisture loss, offering protection against winter damage.