Credit 19th century French novelist and social critic Jean-Baptiste Karr with framing the common observation that the more things change, the more they remain the same. The constraints of usable gardening space in the (modern) urban environment have spawned such contemporary horticultural notions as “vertical gardening” or “wall gardening”. These practices allow city dwellers with little room other than balconies, ledges, or narrow walkways between buildings to enjoy gardening.

But whether it’s a vine covering a wall growing from a ledge on the 92nd floor or flowering plants supported by a trellis (or free-standing) between buildings, we’re in truth reworking the concept of the hedge. Hedges are simply walls composed of plants. They can be rustic or flamboyant; most are grown with a primarily functional purpose in mind—privacy, security, delimiting a walk or roadway, or as a windbreak. But they also offer interest and beauty to the landscape and attract and support wildlife.

Archeologists figure that in Europe the first hedges were planted to enclose agricultural settlements in the Neolithic Age as much as 6000 years ago. They would have served to keep livestock in and predators, wild herbivores, and hostile humans out. Some hedges in Europe still exist from the Bronze and Iron Ages 2000 and 4000 years ago.

Hedges do not have such a long history in North America, but they serve myriad useful and aesthetic functions. We’re staying in a house on a busy street. There’s a masonry wall in front, and sounds from the street reverberate between our wall and the walls across the street. It can be very noisy. I planted a hedge when we first moved here to hide the wall and dampen the street sounds.

My hedge is composed of alternately planted toyon or Christmas berry (Heteromeles arbutifolia) and Arroyo Grande lilac (Ceanothus impressus var. nipomensis). Both are low-maintenance plants adapted to poor soil and low-water conditions and are indigenous to the central coast of California where we’re located, and they are evergreen. Members of the genus Ceanothus enrich the soil by “fixing” atmospheric nitrogen through an association with filamentous bacteria (Frankia spp.). When mature, the hedge will be 8 to 10 feet high (though toyon can grow taller) and 6 to 8 feet wide; the toyon will have red, bird-attracting berries in the winter, and the ceanothus will have profuse lilac-blue flowers throughout the spring that will attract hummingbirds and various insects.

Mine is a free-form hedge that I don’t intend to prune beyond what is necessary for plant health or my convenience. But there are many formal, pruned and shaped hedges in this area. Anyone with even a passing familiarity with California landscaping will recognize that Pittosporum is often used here in hedges. Pittosporum is a large genus of 200 or so species of trees and shrubs; many are adapted for horticultural use and are appropriate for USDA Hardiness Zones 8 to10. Two that are commonly used for hedges are P. tenuifolium (Kohuhu) and P. tobira (Japanese mock orange). Pittosporum tenuifolium grows quickly to about 15 feet and then more slowly, easily reaching 20 feet. It can be shaped to a massive, impenetrable 20-foot wall. Pittosporum tobira does not grow as tall but grows more densely and has orange-scented flowers. Both have shiny, evergreen leaves and also variegated forms. Neither requires much water once established, and P. tobira is a good choice for sea-side locations because of its salt tolerance.

The functional, ornamental hedge grown in Zone 10 is no different from that grown in, say, Zone 5, where my ceanothus would not long survive. The choice of plants is likely different, but the basic considerations are the same, and lots of plants (both trees and shrubs) are well suited for hedges. The decision of what to plant should be made on the basis of the purpose and designs for the hedge and the growing space available.

I prefer low-maintenance plants. If you want a formal, proper hedge, know that you’re committing to a major undertaking. Boxwood and yew are good, standard choices. Common boxwood (Buxus sempervirens) is used extensively for topiary and hedges along walks and in mazes because of its dense growth and rounded form. Boxwood is evergreen and within its several species are cultivars with lots of variation in plant form and leaf shape and color. Most will grow well from Zones 5 to 9. Yew (Taxus spp.) hedges are the quintessential English hedge. They are very long lived plants and the wood is hard but flexible. The English longbow, which revolutionized warfare and was used with devastating effect against opposing armies for 400 years, is made from English yew (Taxus baccata). There are several yew species and cultivars that make excellent hedges and are adapted to most North American environments.

If you want a less time-consuming hedge, plant arborvitae (Thuja occidentalis) or hemlock (Tsuga canadensis). Both are handsome and hardy (Hardiness Zones 2–7); neither is subject to many pests or environmental stresses. Both will look well pruned to a simple squared off wall or allowed to grow as they will (if space permits). I have lived my whole life with a Zone 5 wall-shaped arborvitae hedge that is pushing 80 years old. It long ago out lived its original purpose of keeping the hillside from sliding into Lake Michigan.

Flowering shrubs make great showy, screen-type hedges that accent a garden or lawn or mask a gas meter or the neighbor’s fence. False holly (Osmanthus heterophyllus) cultivar Fastigiata is an evergreen with shiny, holly-like leaves on upright stems. It is easily maintained, has no disease problems, tolerates drought well when established, and will grow to 6 to 8 feet high by about 4 feet wide. False holly has fragrant flowers that appear in fall, and it looks well the entire year. It grows happily from Zones 6 to 9. Variegated Greenstem Forsythia (Forsythia viridissima var. koreana) cultivar Kumson is another good choice. It has classical forsythia-yellow flowers that appear in early spring on bare branches. When these begin to disappear, the silvery veins in the otherwise rather dark leaves become prominent as the foliage matures. It’s a striking plant that will grow to roughly 6 feet high by 6 feet wide.

Windbreaks are another type of hedge. They have been used successfully to ameliorate somewhat the harsh climate of the Great Plains, which is characterized by hot summers, cold winters, and often high wind speeds. These are generally composed of several rows of shrubs and trees of varying heights planted at linear intervals perpendicularly to the direction of the prevailing wind. They create an island of relative calm in the otherwise uninterrupted space of the open prairie. Planted with the direction of the prevailing wind, there might be five rows in this sort of “hedge” going from low to high to low plants and beginning with a row of dense shrubs followed by rows of medium-sized evergreens, medium deciduous or tall evergreen trees, tall deciduous trees, and finally perhaps showy, flowering shrubs or fruit trees such as apple and cherry. See, for example, http://www.ag.ndsu.edu/pubs/plantsci/trees/f1055w.htm; verified 17 September 2010.

For a farmyard in the lee of such a hedge, these windbreaks create a more comfortable working environment in both summer and winter. They reduce wind damage to farm buildings, decrease snow drifting, and provide an energy savings in buildings of as much as 40% relative to unprotected buildings. And there are various products that can be harvested as the windbreak matures, including firewood, fence posts, and fruit. Windbreaks also serve as a significant refuge and resource for wildlife. See http://www.unl.edu/nac/brochures/ec1771/index.html; verified 17 September 2010.

Even without a critical need, planting a hedge, be it on your apartment balcony or suburban lot, is a great garden project. There are almost unending possibilities of plants to use. It will last for years, can be ignored or pampered, and will attract birds and other wildlife and perhaps shelter you a little from the neighbors.