How to Hedge

Sunday, September 15, 2002

The notion of defining or surrounding outdoor space with plants grown in rows--hedges--can be traced back at least as far as ancient Greece (2100 BC). The very name, ‘garden’, derives from the same root words as enclosure, yard, and even girdle, meaning ‘to surround.’ From mankind’s first cultures, hedges have marked the boundary between the cultivated garden and the chaos of the larger world. Today’s gardens continue to enclose space but have other landscape uses: to retain the view of the world beyond, to extend the lines of architecture into the garden, to direct traffic, screen unwanted scenes, and create a background for other plants.

Hedges became sources of amusement during the Dark Ages, when they were used to grow mazes. These living puzzles were designed for view from above, where spectators laughed at the bewildered trying to exit the maze. Except for the gardens at Williamsburg, almost no one in America grows an eight-foot tall hedge maze nowadays.

An eight foot hedge encloses and excludes most effectively. But  when choosing a hedge plant, consider whether its height will match your needs. A hedge maintained at 3 feet high will discourage people from crossing it, but it takes a five foot tall hedge to restrain or redirect them. Low hedges may create a psychological wall, but retain the view and the breeze, while taller ranks of shrubs will mentally remove both.

In general, choose evergreen shrubs for garden walls, screens, and background and let deciduous shrubs provide more the illusion of privacy. Choose shrubs that can withstand your area’s climate, and look for additional features beyond just green leaves: flowers, berries for wildlife, fragrance, fall color, and spring growth color.

Informal hedges rely on pruning to maintain natural shape. The eye sees them in a curved, soft profile, and they may need larger space in the garden to show their form. But informal hedges are more forgiving; pruning is less crucial. Their opposite type, the formal hedges, bring geometric shapes creating sharper lines, and may require more frequent pruning to maintain. 

Get your hedge off to the best start by preparing the soil as recommended in your area. Rather than dig individual holes in the native soil, prepare a bed for the hedgerow whenever possible. The more room for the shrubs to establish themselves without competetion, the better. A bed will allow delicate feeder roots to thrive and make weed control easier.

Pruning holds the key to maximizing shrub growth. Prune first at planting time to remove any broken branches, and any that rub against each other in the interior of the plant. When planting a hedge of one species, prune them to match. If roots get damaged in transplant, prune the top to compensate.

Prune evergreens and summer-bloomers in winter or very early springIn the first year of growth, keep mulched, water and apply root stimulator fertilizer weekly for two months, then water twice a month, fertilize with shrub food at midsummer, and apply winterizer formula in late summer. Trim wild sprouts and tip prune to develop shape.

Continue tip pruning monthly until about six weeks before freezing weather in your area. Fertilize again in midsummer and apply winterizer in late summer. Water weekly. 

In the third year, begin a longterm maintenance program.

Prune to shape, do not shear shrubs for fastest growth and most natural form.

For shrubs like forsythia, with fast growing tops, cut back one third of each stem each year.  For multi-stemmed shrubs like spirea, take out one fourth of oldest canes to the ground each year and tip prune younger ones.

When you say ‘hedge’ to most people, they think of privet or boxwood, and both are still widely used. But more shrubs make terrific, easy to grow hedges, and even the old stalwarts have improved selections that do the job better.
California Privet, Border Privet (LIgustrum) set the standard
Littleleaf Boxwood (Buxus) better than English for basic hedging
Vanhoutt Spirea (S. x vanhouttei) best flowers farthest south
Rugosa, Carefree, and Fairy Roses (Rosa) reliable flowers on thorny barriers
Purple Willow (Salix purpurea) dark, blue green, best for moist areas
Arrowwood (Viburnum dentatum) for arching form, salt tolerance
Winter Honeysuckle (Lonicera fragrantissima) for best fragrance
Compacta Holly (Ilex crenata) use instead of boxwood, hardiest is ‘Glory’
Wintergreen Barberry (Berberis julianae) evergreen, impenetrable

This is the unedited version of an article that appeared in Garden Almanac, a publication of GroGroup. 

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