Betting your hedges

I was helping a friend solve a design problem in her garden:Should she continue the existing hedge to completely enclose hersmall urban front yard or remove it entirely?

Needing more information before I could advise her, I answeredwith a question of my own: "What type of hedge do you have?"

Puzzled, she replied: "You know--hedges!"

A beginning gardener, she failed to grasp that "hedge" was not asingle plant species, but an architectural landscape feature thatcould perform multiple garden functions and consist of any number ofdifferent plant varieties. To her, all hedges looked alike.

Hers turned out to be a privet hedge, the most common deciduousplant used to build hedges here in southwestern Pennsylvania. Privetis also a perfectly valid reason to wrinkle a nose when a gardendesigner suggests planting a hedge.

Had it been an evergreen hedge, chances were overwhelmingly infavor of yew.

Gardeners use hedges for two important jobs: enclosure andframing. Most specific uses--privacy from neighbors, definition offormal herb beds, to backdrop a perennial border, as a screen forwall or fence--fall into one of those two categories.

Interpreted broadly, the concept of a hedge can even be expandedto include landscape features like large informal shrub borders,particularly when they're used as barriers or screens. I think thatdefinition is unnecessarily confusing, but I notice more and moreprofessionals using the term "hedge" to describe mixed shrub borders.

Indeed a hedge can be planted strictly for show. Given enoughspace, who wouldn't want the gorgeous tapestry hedge described inWhite Flower Farm's 2002 catalog? Typically, however, hedges have adefinite purpose in the landscape.

That doesn't mean they can't be pretty. In fact, they should be.And that premise all but excludes privet from the list of potentialhedge plants.

Specimens with small leaves and dense growth habits, such asboxwood, make the best formal hedges. They adapt well to clipping andcan be tightly or loosely sheared to achieve the desired effect.

Formal hedges are beautiful, but definitely "high maintenance,"requiring frequent grooming to keep them neat and tidy.

Be sure to research boxwood varieties carefully before planting aformal hedge. Dozens of cultivars are available. For large-scaleprojects, choose a robust variety such as 'Winter Gem' over a slow-growing miniature like 'Green Gem.'

In addition to boxwood, Japanese holy, inkberry holly, and yewmake excellent formal evergreen hedges.

Though they're commonly clipped into formal shapes, I think blueholly, arborvitae, and chamaecypraris serve better in informalsituations. Shearing turns leaf edges ragged and brown. New growth isslower to cover it up than with faster-growing, small-leaved plants.Try hand pruning these special varieties once or twice a year for asofter, more natural look.

Informal deciduous hedges offer gardeners a lot of flexibility.Undulating shapes, varying heights, and widths, colorful booms, andelegant foliage fill different landscape needs.

I credit the hedge display at the Holden Arboretum, nearCleveland, Ohio, with opening my eyes many years ago to the diversityof informal hedge-making materials. Chicago Lustre arrowwood viburnum(V. dentatum 'Chicago Lustre') has since become a favorite of minefor large informal gardens.

For an inexpensive fast-growing or temporary hedge, considerornamental grasses. They don't offer much privacy during the briefperiod in spring after they've been cut down, but they'll quicklygrow into a dense green curtain for summer and fall. Try maiden grassif you need something tall, fountain grass for a shorter hedge.

To keep all hedges, but especially evergreen varieties, looking--and behaving--their best, always trim them so that the bottom of thehedge is slightly wider than the top. If sunshine can reach thebottom of the plant, foliage will respond better to pruning, and thehedge will stay dense all the way to the ground.

Horticulturist Lindsay Bond Totten writes about gardening for theScripps Howard News Service.