Maryland Grows

Q:  I have always loved the look of blue spruces, and I see many Maryland nurseries stocking them. I’ve heard that I should consider alternatives, though. Why?

A:  Although every plant has something it can be vulnerable to (pests, diseases, environmental stress) and nothing is risk-free, Colorado spruce (Picea pungens), the species with the popular blue-needled cultivars, struggles in Maryland growing conditions. As such, it is at risk for several problems that cause dieback and significant aesthetic damage. Overall, spruces as a group are not well-adapted to high summer heat and humidity, or compacted or clay-dominated soils common to urban or suburban landscaping.

No spruces are native to the state except for the tip of western Maryland, where the locally rare red spruce grows in the mountains. (Maryland Biodiversity Project notes that prior logging and wildfires reduced this already limited population.) You can see from the spruce species range maps on the Biota of North America Program website that no other spruce species grows wild anywhere near Maryland.

Due to the particularly damaging nature of the issues spruces can develop here, primarily from fungal infections — drastic needle browning and shedding, plus branch dieback — I suggest using alternatives if you want a large-statured, pyramidal, and/or blue-leaved evergreen specimen tree. This spruce decline issue is prevalent enough that it has its own University of Maryland Extension web page, “What’s Wrong with my Colorado Blue Spruce Tree?”

A substitute plant won’t necessarily look the same (it might have broader or looser branching, or won’t have blue foliage), but it can have a better chance of thriving. Your options will depend on the site conditions, including how much space you have for the plant to mature, though your best range of choices will be for a location in full sun (in summer) with good drainage and no deer browsing pressures.

Few locally native species are evergreen and large-statured, but they include American holly (Ilex opaca), Eastern redcedar (Juniperus virginiana), and Atlantic whitecedar (Chamaecyparis thyoides), the latter of which is rare, unfortunately hard to find for purchase, and limited to the coastal plain in the wild. Several species of pine grow wild throughout Maryland, but their mature habit is quite different from spruce.

Non-native candidates include other holly species or hybrids, Japanese cedar (Cryptomeria japonica), true cedars (Atlas Cedar, Cedrus atlantica, and Deodar cedar, Cedrus deodara), and Western arborvitae (Thuja plicata). Arizona cypress (Cupressus glabra) and atlas cedar come in silvery-blue forms if you want a foliage color similar to blue spruce. While leyland cypress (Cupressocyparis leylandii) is commonly planted, it suffers from some serious shortcomings that can make it short-lived and prone to fungal branch dieback.

Whichever plants you try, use a mix of species if you’re growing them in a group, like a screen or living fence, rather than mass-planting only one species or variety. This helps the planting to resist future pest, disease, or weather stress problems, since different species have different tolerances and vulnerabilities. That way, a future issue won’t be likely to impact them all equally severely, like a fungal needle cast infection wiping-out a row of blue spruce.

By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.

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