The old proverb says: Good fences make good neighbors. But what do good garden walls make? They make a lot more than one intends and are the best concrete definition of “unintended consequences.”

Thick walls provide protection from steady winds and sudden gusts at the outer edge but intensify them within. Shade falls on the shy and bold but which one do you want to benefit and in what season? Heat is retained and dispersed but when did you want that to happen? Moisture may be conserved but which plants merit that concern and which will melt into a fungal pool?

History
The garden wall throughout its history has subtly blended practicality with art. In Persia as far into the past as 4,000 BC, garden confines provided cooling shelter—respite from the day’s troubles. It is from the Persian word for “enclosed space” —pairi-daeza—that the word paradise evolved.
Along the Nile, wealthy Egyptians built walled gardens for the same purpose as the Persians, employing wells and sunken aqueducts to plump fragile fruits like apricots and grapes. In cooler climes the Chinese composed their gardens as oases of fantasy and contentment, while outside, agriculture waged war on the elements.

In England, where space is precious, garden barricades kept thieving humans from plundering the harvest of ordinary and exotic fruits and vegetables during plenty and scarcity.

This hemisphere’s pre-Columbian garden barricades prevented human invasions, too, but also provided boundaries and protection from the encroaching jungle.
I have found no references to ancient treatises on the aerodynamics of vertical barriers, no eureka-moment by a gardening equivalent of Archimedes, which is puzzling, for garden walls make significant changes in local climate that can devastate or cultivate whatever lies on both sides.

Wall Facts
Protection extends only to a distance of twice the height of the wall, from six inches to six yards or more.

Though protector of the tender and fragile, garden walls create a devilish interior vortex when gusts meet the outer face. Strong winds are scarcely stopped; they will rip down the other side scouring the soil and tearing whatever grows.

Slow and soften these inner eddies with tough, feathery upright shrubs—arborvitae, false cypress, viburnum. Just beyond, low growing plants will thrive.
The ancient walled gardens of desert river valleys and oases created welcoming shade but also evening heat-traps against plummeting temperatures. Your garden shield, whether a four-sided enclosure or a two-sided niche, will do the same: those made of stone, retaining the warmth longest. Unless the garden is open to the southwest, ice and snow will last longer, as winter shadows retreat slowly.

At a recent tour of the serpentine brick-walled gardens of the University of Virginia’s Academical Village, I learned that interior summertime temperatures exceed exterior conditions by more than 20 degrees F. Spring may come early but summer cooks and lingers longer. What garden in Central Virginia needs fevered summer nights?

Erect a garden wall, embracing all its virtues—refuge, beauty and abundance but be prepared for all its vices—temperature, light and wind.

TIP OF THE WEEK
Birds will eat green berries, so protect fruit trees, vines and brambles with fine meshed netting before they ripen. If you must use an insecticide, spray at dusk after the bees and other pollinators have finished foraging for the day. Propagate perennials and shrubs with woody stem cuttings, now. Prune summer ornamentals, viburnum and weigela, just after blooming.