Native Evergreen Plants

A regional asymmetry worth knowing

Eastern North America has relatively few native broadleaf evergreen shrubs. The hollies, mountain laurel, rhododendrons in the Appalachians, and a short list beyond that. This is why so much eastern landscaping leans on boxwood, Japanese holly, and euonymus, none of which are native and one of which is invasive.

The West has many. Manzanita, ceanothus, toyon, Oregon grape, and others hold their leaves through winter and form the structure of chaparral and dry woodland.

If you garden in the East, the practical native evergreens for structure are inkberry and the hollies, plus Christmas fern and foamflower at ground level. If you garden in the West, the choice is wide.

What evergreen structure does in winter

Two things, and neither is only about appearance.

It gives the garden something to look at for the four or five months when everything else is bare, which is a real argument in a northern climate.

And it provides cover. Winter shelter is genuinely scarce, and dense evergreen foliage is where small birds roost overnight against cold and hide from hawks. A yard of deciduous shrubs offers food in winter and no protection.

The hedge decision

Clipped evergreen hedges and foundation plantings are usually boxwood, and boxwood is under serious pressure from boxwood blight, which has spread across much of the country and can destroy a planting.

Inkberry holly is the native replacement in the East at roughly the same scale and takes shearing. Its known weakness is losing lower leaves with age, which newer selections were chosen to resist. In the West, toyon and the taller ceanothus make screens and hedges.

Match the species to the conditions rather than to the shape you want, and accept that a native hedge will look somewhat looser than clipped boxwood.

Winter care and the things that go wrong

Broadleaf evergreens lose water through their leaves all winter while frozen soil prevents replacing it, which is what causes the browned scorched foliage that shows up in March. Wind and winter sun both worsen it.

Two preventions: water deeply in late fall before the ground freezes, and site plants out of harsh winter wind and reflected afternoon sun rather than against a south-facing wall.

Check soil pH for the hollies and Oregon grape, which want acidic conditions and yellow between the leaf veins in alkaline ground.

And do not shear in late summer. New growth needs time to harden before frost.

Sources: Lady Bird Johnson Wildflower Center, University of Texas at Austin (species profiles and regional distribution); Mt. Cuba Center (Ilex glabra trial results); US Department of Agriculture and university extension (boxwood blight distribution and management, winter desiccation in broadleaf evergreens).