Cedar trees are admired for their evergreen foliage and distinct forms. For these trees to thrive, understanding their specific growing requirements is crucial. Matching the cedar tree to an appropriate growing zone is a primary consideration for successful cultivation.
Understanding USDA Hardiness Zones
The USDA Plant Hardiness Zone Map is a primary tool for gardeners, indicating which perennial plants are likely to survive winter in a particular location. This map divides North America into zones based on the average annual extreme minimum winter temperature. Each zone represents a 10-degree Fahrenheit difference, with further subdivisions into ‘a’ and ‘b’ for a 5-degree difference. The USDA map is periodically updated, with the most recent revision occurring in 2023. Gardeners can use their zip code to quickly identify their specific hardiness zone. This system helps prevent plant failure due to cold by guiding plant selection to those species capable of withstanding the lowest temperatures of a given area.
Cedar Tree Varieties and Their Preferred Zones
The term “cedar” is often broadly applied to several coniferous trees, but true cedars belong to the genus Cedrus. Other conifers commonly called cedars include junipers (Juniperus), arborvitae (Thuja), and false cypress (Chamaecyparis). Each type has distinct hardiness zone preferences.
True cedars (Cedrus) are known for their majestic size and distinctive cones. Deodar Cedar (Cedrus deodara) is hardy in USDA Zones 7 through 9A, though some cultivars originating from colder regions can tolerate Zone 6, surviving temperatures down to about -22°F. Atlas Cedar (Cedrus atlantica), native to the Atlas Mountains, is hardy in USDA Zones 6 to 9, or even 5 to 9. The Cedar of Lebanon (Cedrus libani), considered the most cold-hardy among true cedars, thrives in USDA Zones 5b through 10A, with some strains tolerating Zone 5a.
Among the “false cedars,” the Eastern Red Cedar (Juniperus virginiana) is a juniper species widely adaptable across USDA Zones 2 through 9. Western Red Cedar (Thuja plicata) is hardy in USDA Zones 5 to 9 and is native to the Pacific Northwest. Northern White Cedar (Thuja occidentalis), also known as Eastern Arborvitae, is resilient in USDA Zones 2 through 7.
Key Environmental Factors Beyond Growing Zones
While hardiness zones are a primary consideration, other environmental factors significantly influence a cedar tree’s health. Soil type is crucial, as cedars prefer well-drained soil with a slightly acidic to neutral pH, typically between 6.0 and 7.5. Heavy clay soils can lead to root rot, so improving drainage with organic matter may be necessary.
Sunlight is another important factor, with most cedar varieties thriving in full sun (at least six hours of direct sunlight). Some species can tolerate partial shade, but full sun promotes better growth and foliage density. Water needs vary, but established cedars are drought-tolerant. Young trees require consistent watering, especially during their first few years, to develop a robust root system.
Selecting and Caring for Cedar Trees Based on Your Zone
To select a cedar tree, first identify your specific USDA hardiness zone using online tools or local nursery resources. Choose a cedar variety reliably hardy for that zone to ensure successful establishment and long-term survival.
Proper planting techniques are essential. Dig a hole twice as wide as the root ball but no deeper than its height, ensuring the root flare is exposed. Backfill with soil, avoiding tight packing, and create a slight depression to help retain water. Mulching around the tree’s base conserves soil moisture, regulates temperature, and suppresses weeds; keep the mulch a few inches away from the trunk.
During the establishment period (the first one to two years), consistent deep watering is necessary, especially during dry spells. In colder zones, ensuring adequate moisture in late fall helps evergreens withstand winter drying.