Evergreen trees, including needle-bearing conifers like pine and spruce, and broadleaf species such as holly, retain foliage year-round. This provides consistent color and structure to the landscape, even throughout the winter. Since they never truly go dormant like deciduous trees, evergreens continuously require attention to maintain internal moisture and structural integrity. Successful long-term care involves a proactive, year-round approach that begins the moment a tree is placed in the ground. Understanding the specific needs of these long-lived plants ensures they remain healthy and vibrant for decades.
Proper Planting and Initial Establishment
The long-term health of an evergreen begins with careful selection of the planting location, considering the tree’s mature size and sun or shade requirements. The planting hole should be dug two to three times wider than the root ball, but no deeper. This wide, shallow hole encourages the roots to grow outward into the surrounding soil.
Completely remove any burlap, twine, or wire basket material around the root ball before planting. These materials will not decompose quickly and can girdle the roots. If the roots appear tightly wound or matted, gently score or tease them outward to encourage establishment. Position the tree so the root flare—where the trunk widens at the base—sits slightly above the surrounding grade to account for settling and ensure proper drainage.
Backfill the hole with the original soil, tamping gently to remove large air pockets without compacting the material. Immediately after planting, a thorough and deep watering is necessary to settle the soil. During the first growing season, newly planted evergreens require consistent moisture. Deep watering once a week, or more frequently during hot, dry periods, encourages a robust root system.
Ongoing Water and Soil Management
Established evergreens require careful management of soil moisture throughout the year to prevent desiccation, especially in winter. Since foliage transpires moisture even when the ground is frozen, deep watering in late fall before the first hard freeze is necessary. During periods of winter thaw or severe drought, supplemental watering may be needed to replenish the tree’s internal water reserves.
Watering should be done deeply and slowly, allowing the water to penetrate the entire root zone, which typically extends to the dripline of the canopy. Avoid frequent, shallow watering, as this encourages surface roots vulnerable to stress. Well-drained soil is important, as evergreens are highly susceptible to root rot in waterlogged conditions.
A layer of organic mulch, such as shredded bark or wood chips, is beneficial for soil management, helping to moderate temperature and retain moisture. Apply a layer three to four inches deep, extending from the trunk out to the dripline. Keep the mulch several inches away from the trunk flare to prevent moisture buildup against the bark, which can lead to decay and harbor pests.
Fertilization is generally less frequent for evergreens, and mature specimens often require little unless a soil test indicates a deficiency. If necessary, apply a slow-release, balanced formulation, such as a 10-10-10 or similar ratio, in early spring as new growth begins. Never apply a nitrogen-heavy fertilizer after mid-summer, as the resulting tender growth will not harden off before winter, making it susceptible to cold damage.
Structural Maintenance Through Pruning
Pruning evergreens maintains shape, controls size, and removes damaged or diseased wood, focusing on selective cuts rather than shearing. The optimal time for most species is late winter or early spring, just before the first flush of new growth, when the tree is still dormant. Pruning during this period minimizes stress and allows the tree to quickly conceal the cuts.
Specific techniques vary depending on the type of evergreen. Pines are managed by “candle cutting,” which involves pinching or cutting the soft, new growth shoots back by about one-half in mid-to-late spring. This technique causes the branch to become denser and slows elongation. Conversely, species like juniper and arborvitae will not regenerate if cut back past the green foliage, a condition known as the “dead zone.”
Selective pruning, where individual branches are cut back to a side branch or a bud, is preferred over shearing, which only cuts the outer layer of foliage. Never remove more than one-third of the total foliage in a single season. Dead, broken, or rubbing branches can be removed at any time of year without harm.
Identifying and Addressing Common Threats
Regular inspection is the first line of defense against common biological and environmental threats. Needle discoloration, sap oozing, or fine webbing can signal a problem, requiring immediate, targeted action. Maintaining a healthy tree through proper watering and mulching helps the plant resist pests and diseases naturally.
Biological threats include fungal diseases like Rhizosphaera Needle Cast, which causes older, inner needles to turn purplish-brown and drop, starting from the lower branches. Pests like spider mites thrive in hot, dry conditions and cause stippling or bronzing of the needles, often leaving behind fine silk webbing. Scale insects appear as small, immobile bumps on the stems or needles, feeding on the sap and causing branch dieback.
Environmental threats are equally damaging, with winter burn being a common issue. Winter burn occurs when frozen soil prevents water uptake while winter sun and wind cause the needles to transpire moisture. This results in a reddish-brown discoloration on the exposed side of the tree. Salt damage from road de-icing can also cause browning and dieback on nearby branches.
Addressing these issues often starts with cultural control methods, such as pruning out affected branches to improve air circulation and physically removing small infestations. For pests, a strong jet of water can dislodge mites, while horticultural oils or insecticidal soaps can treat scale and other sapsuckers. Ensuring the tree is properly hydrated going into winter is the most effective preventative measure against winter burn.