Although apples trees can be beautiful ornemental plants even if they don't really belong on wall espaliers but in an open field. Wire trellises such as the 0050 may be used to build free standing trellises. Most apple varieties are already hard to cultivate outdoors and won't really benefit from a wall microclimate. Instead of using the extra heat to mature faste they tend to lose their aroma and tanginess (acidity) and become susceptible to diseases or pests. They should only be grown as espaliers next to walls when no space is available in the garden.
(lat.: Malus domestica)
Apples should be grown on west facing walls, because apples may "boil" if the temperature is too high. The soil should be deep, humose and damp with a good water supply. The weaker the grafted rootstock, the less the tree should share the soil with other plants, bushes and grasses. In the most extreme cases the ground needs to be mulched. Apple trees are available in tree nurseries or online.
Two matching apple varieties must always be present near each other so as to ensure fertilisation, either as two individual plants or as one espalier apple with double grafting. There are special varieties for espalier whose fruits are in high demands as rarities, such as "White Winter Calvill". Many of the old varieties are susceptible to mildew and can't be used as wall espaliers. New, multi-resistant varieties are often better suited.
Apple trees are always grafted. For small or low trellises (height x width: 3 m x 2 m) mostly on the slowly growing base "M 9". Such graftings are then sold as "low trunk", "quarter standard", "bush" or "tall spindles". There are also expensive trees available that are pre-trained as espaliers. The lifespan of an espalier is only 20 years. For medium-sized espaliers (height x width: 4 m x 3 m) apples on the stronger base "M 26" should be used, these trees are sold as "half standard". Larger trellises (height x width: 6 m x 3 m) require medium-strong rootstocks such as "M 4", "M 7" or "MM 106", which can last for 30-50 years.
Columnar apple tree and dwarf fruit trees aren't suitable as facade espalier trees.
There is a table of all suitable shapes for wire rope trellises a the bottom of the page. For an optimal distance between the tree and the facade, choose a trellis in the heavy or massive range, if needed also in the middle or simple ranges. Pear espalier trees can be grown on a wooden trellis. In a field, use a 0050 trellis.
The trees are trained to their final shape through pruning, bending and binding. Apple espaliers are usually grown as "tall spindles" (see photos below). Older names for this shape are "vertical cordon" or "vertical cord tree". The fruit bearing wood branches off directly from the middle trunk and the shoots are tied horizontally 60 cm above the ground in levels of every approx. 40 cm. When apple trees are planted next to each other they build long hedges. Other shapes such as the Palmette Verrier are used for larger trellises. Technical literature on pruning is available online. Without correct pruning technique, the trees will bear less fruits and may not bear any fruit at all. The design of the trellis and the shape of the tree need to fit each other. As described in "Shaped trees", the main axes of the trellis should be 35 - 40 cm apart.