Usable garden space is always an important factor in the home garden. My friend, Hugh Glass, has always grown fruit trees at his home—apples and cherries mostly but occasionally some others such as plums and peaches. He recently moved from a house with almost 2 acres in Wisconsin to one with about 0.40 acres in California. He no longer has the luxury of being able to plant trees more or less wherever he wants.

Here’s his advice:

Espalier is a good option for the home gardener with limited space. Espalier refers to both the plant and the technique whereby trees or bushes are trained to grow in a plane against a wall, fence or trellis.

Espalier is becoming more widespread, but it is not a new idea. The technique used with fruit trees was known in the Greco–Roman world. After the fall of Rome, espalier was used within walled towns and monasteries of medieval Europe. The origin of modern espalier is 16th century France and England where fruit trees were grown against walls for radiated heat and shelter in an attempt to remediate a marginal fruit-growing climate.

During the Victorian Era (1837–1901), Britain became extremely prosperous and influential, and espalier was used extensively as gardens gained popularity and served as status symbols. The Victorian garden tended to have high walls that enclosed a long, narrow garden that was an ideal space for espalier.

Knowledge of how plants grow is helpful for understanding espalier. In a basic sense, plants grow by elongation and differentiation of buds (what botanists call “meristems”). When a plant grows taller, the main, central (generally uppermost) meristem elongates and differentiates; lateral buds, flowers, leaves, and more stem are produced. All plant growth, and what a bud becomes are determined by an interaction among the genes a plant possesses, plant hormones, and environmental conditions.

The uppermost bud, meristem, or growing point partially suppresses the growth of buds farther down the stem; buds closest to the uppermost bud are suppressed the most. This effect of this is clearly seen in young trees where lower buds have become well developed branches while upper ones are still small branches or buds only. This phenomenon is called “apical dominance”, and it is mostly controlled by auxin, a plant hormone. If the uppermost bud is removed, the primary source of auxin is removed and the partial dormancy of the lower buds is broken, and those buds begin to elongate and differentiate.

In general, pruning fruit trees almost always reduces yield, but the quality of the fruit is enhanced. Pruning opens the tree to better light penetration and air flow within the canopy. Pruning encourages the growth of new shoots with high-quality flower buds; fruit size increases as excess flower buds are removed and the tree’s energy is concentrated in the remaining buds.

In espalier, pruning in conjunction with branch training produces additional beneficial results. Espalier fruit trees yield earlier and more abundantly, relative to the amount of wood they possess, than do normally pruned fruit trees. The key to this is the effect pruning and branch training has on the concentration and location of auxin in the tree.

Branches that are oriented from vertical to about 60° have a fairly even distribution of auxin around the limb, and around the limb, buds develop into shoots more or less symmetrically with those farthest from the branch tip growing most. In branches oriented at about 70 to 90° from the main stem, auxin tends to accumulate on the underside of the branch and inhibits bud growth there. Buds on the upper side, however, where the concentration of auxin is low, are not inhibited and develop along the length of the branch. There are also additional buds embedded within the bark that are normally dormant but that begin to grow when the concentration of auxin is insufficient to maintain dormancy. These are “watersprouts”, or suckers, if they appear from the roots, and are normally a nuisance in fruit trees.

There are several traditional espalier forms. The “cordon” is the primary and probably most familiar form. Branches are trained to grow horizontally from a main stem. A multi tier cordon generally has three tiers of branches, and the tree is 6 to 8 feet high. “Palmetto verrier” is a form in which branches are shaped into a “U” by turning horizontally trained branches up at the ends. This form can be modified by training branches to grow at 45° rather than 90° from the main trunk. Within any of the traditional forms, lots of variation is possible. A tree trained as a cordon, for example, may be trained to have two trunks. It’s also possible to braid multiple trunks or branches, forming a hedge or screen (Belgian Fence). Please see this useful Univ. of Florida circular for form descriptions http://groups.ucanr.org/mgnapa/files/65112.pdf; accessed 6 September 2009.

Apples and pears (“pome” fruits) are most commonly trained in the traditional espalier forms. Peaches, cherries, and other “stone” fruits are usually trained in a more informal style. Stone fruits bear fruit on the previous year’s growth. As a result, each year two sets of branches must be trained in parallel, one that produces fruit in the current growing season and one that will produce fruit in the next. So during dormancy, the branches that bore fruit during the last season are removed, and a new set of branches is trained adjacent to the branches that will produce fruit in the current year.

Espalier has purely ornamental value as well. Many common ornamental plants can be adapted to either the more traditional forms or informal styles. There are many worthwhile possibilities that include anise, bougainvillea, camellia, cotoneaster, winged euonymus, forsythia, hibiscus, holly, jasmine, juniper, magnolia, maple, viburnum, witch hazel, and yew. Some varieties will be better choices than others.

Classic topiary uses espalier techniques. Heronswood’s research garden at its original location in Kingston, Washington, has a very beautiful one, consisting of a refined Belgian fence of European hornbeam, or a sophisticated pleaching that forms a large room or alcove in the middle of which rests a small fountain and pool. Dan called it “the gothic room”. The effect is quite stunning.

Espalier maximizes garden space while the trees produce plenty of fruit for a household; it also presents a striking, sculptural display. Espalier can be an engaging and rewarding project that requires attention and planning.

—Hugh Glass

 

For growing Classic Espalier against a wall, we offer the following selections at Heronswood:

Buxus sempervirens ‘National’
Buxus sempervirens ‘Elegantissima’
Cornus stolonifera ‘Hedgerow’s Gold’
Schizophragma hydrangeoides ‘Moonlight’
Schizophragma hydrangeoides ‘Roseum’