Indoor Espalier - Australian Finger Lime

It poked me a few dozen times with its sharp thorns, but I managed to set up this grafted Australian Finger Lime (Citrus australasica) tree to train as an Indoor Espalier.

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The original vertical garden, espalier is a an ancient gardening method that maximizes use of growing space with fruit-bearing trees trained to grow along walls and fences. The free air movement and light penetration through the center of the two-dimensional plant also hastens fruit ripening and discourages disease pathogens. Thousands of acres of Apple production capitalize on these benefits with trees grown along trellises—this is essentially espalier training—but the technique was apparently first used in Iron Age Europe. Espalier later became more widely used during the Medieval Period. There are claims from folklore of fruit trees espaliered along the interior curtain walls of castle courtyards to feed inhabitants during military sieges. While it seems doubtful that the crop from a few trees could sustain a small kingdom army, trees growing in this way would have certainly benefited from the stone surfaces warmed by the sun.

Indoor Espalier is an adaptation of this old-fashioned technique updated for interior spaces. It is also intended as a simplified alternative for living wall or vertical garden plantings. Along with bright artificial lights, these designs, planted with dozens or hundreds of individual plants, usually employ mechanical pumps along with plumbing, waterproofing and load-bearing structures. Indoor Espalier, on the other hand, uses just a single tree trained to grow along an unmodified wall or panel surface. Rooted in a wall-mount planter, the Indoor Espalier tree is irrigated by hand like a regular houseplant. Energy-efficient LED lamps sustain the tree’s growth and vigor, while also providing spillover area lighting.

While it has some advantages with simplified hardware and care, Indoor Espalier requires extra time and attention to achieve a living wall effect. The photograph below shows a Calamondin (x Citrus mitis) that has grown to cover most of a wall panel after almost two years of training. It started out as a rather spindly one-gallon nursery plant, but during the training the LEDs provided room lighting and the training, achieved with bud pinching, pruning and branch arrangement, was a gratifying garden pastime. The Calamondin has not yet produced any fruit, but it bloomed with sweet-scented citrus flowers during its first winter here.

Keep scrolling to see a few additional planting and training details for the Australian Finger Lime Indoor Espalier.

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Indoor Espalier trees grow in vertical cylinder planters mounted to the wall surface. The picture below shows the sturdy mount bracket assembly with steel hose clamps.

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Here the Finger Lime is positioned on the wall and ready for espalier training. The planter is built from a section of 4” plastic pipe with a Corten steel faux metal finish.

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For espalier training, a few of the tree’s branches were trimmed away, while the rest were secured against the wall surface with light plastic zip ties threaded through small steel screw eyes. As the Finger Lime grows, the branches will assume this two-dimensional vertical form and require fewer tie points. The tree will create a more convincing living wall effect when it has about 100% more foliage.

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Thank you for reading! Stay tuned for future posts. We’ll write again with growth updates for this tree, as well as new Indoor Espalier projects with new varieties and species.