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.


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.


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.


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.


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.


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.

'Estonia' - A Model Ecosystem Recreates a Baltic Forest.

With some light pruning, refreshed leaf litter and a spray of clean rainwater, we tidied up one of our favorite terrarium displays this evening. 'Estonia' is built into a 37G (140L) Column enclosure (20" X 18" X 24" [31cm X 46cm X 62cm]) with plants and other features evoking a Baltic woodland with Birches, Firs and a ground layer of soft Ferns.


This Model Ecosystem built in Dojō Terrarium style is very easy to maintain and designed to endure for at least several years. An "egg crate" light diffuser plate supports a rooting substrate comprised mainly of porous gravel (similar to bonsai tree soil) and allows for free drainage and siphon removal of irrigation water. A groundcover of dried leaves, conifer cones and found objects creates a convincing forest floor microhabitat, while a trio of Birch tree poles reach to the top of the tank, providing vertical dimension and creating an appearance of mature canopy trees. A 12-volt fan provides internal air circulation with a gentle breeze.


The terrarium ecosystem was designed only for live plants and does not house livestock, but the antlered skull of a Roe Deer (Capreolus capreolus) lies hidden among the dried leaves and fern fronds to complete the effect of a cool, sun-dappled Baltic forest and its countless mysteries.   


Paleo Terrarium

This Model Ecosystem project interprets evolution, ecology and environmental change concepts with a terrarium planting recreating a Late Cretaceous (68 million years before present) North America forest. The roomy (85 gallon [322L]) glass enclosure will house plants that grew in this ancient landscape, while diorama elements will represent a part of the non-avian dinosaur fauna.

Flora selected for the planting include groups that still survive in our era, but represent very old evolutionary lineages and were more abundant during the Age of Dinosaurs:

  • Calocedrus Incense Cedar - This evergreen tree plays the role of vast conifer forests that grew before Angiosperms (the flowering plants) became the dominant flora all around. While Calocedrus is a canopy tree that reaches 200 feet (60 meters) in height, it can grow well indoors under moderate light and can be pruned like a bonsai to control its size.
  • Gnetum gnemon - This very unusual small tree resembles a Coffee bush, but is in fact a Gymnosperm that survives today as a relic of an evolutionarily old group.
  • Pharus Grass - This is one of the most evolutionarily basal of true grasses. With broad leaves, it looks more like a Ginger or similar tropical plant and may resemble the earliest of grass species.
  • Polystichum Rock Fern - Ferns are among the oldest of living plant groups. This selection grows well in terrariums and, repeated as several individual clumps, creates a soft terrarium groundcover layer.
  • Zamia Cycad - With fossils more than 300 million years old, the Cycad lineage extends into the deep past, The species selected for this project, Zamia vazquezii, is easy to grow and stays smaller than most others.

The tank currently has a floor lining of simple light diffuser panel. This material will be elevated with spacers to create a drainage layer, then covered with a high-drain soil medium ready for planting. After plants are arranged, a forest floor leaf litter will be added to cover the soil layer for a natural appearance. Thee or five slender Cedar tree trunks (representing the fossil conifer tree canopy) will be positioned as features to develop the vertical dimension, while the growing plants fill out this effect. The pair of shots below shows a terrarium display of similar construction, the Dojō Terrarium style, in a smaller (37 gallon [140L]) tank with a trio of Birch stems zip-tied in place and with the plants and other elements added in following steps.


A replica ground nest will represent dinosaurs in this living display. Recent discoveries gleaned from fossils unearthed in Canada has found the smallest non-avian Dinosaur yet known from North America. The diminutive Hesperorynchus was only about as large as a small Chicken (4lbs [1.8kg]) and lived in present-day Alberta. While fossilized eggs of this animal have never been found, fossil traces of related species can be used to approximate its eggs and nest. Hesperorynchus and its relatives had eggs that were only about 1/2 as large as birds of similar sizes. A small Chicken, such as a Silky hen, might lay an egg with a volume of about two cubic inches (33cm3). To build the replica, a proposed Hesperorynchus egg with a volume of one cubic inch (16cm3) was first rendered with 3D drawing software, then turned on a wood lathe by hand. A silicone rubber mold was made from the turned egg, then used to cast additional replicas in epoxy resin. The next photograph shows the whole clutch of replica eggs from the mold. The single finished egg at lower left was sanded smooth, then painted with a faint green enamel paint. Fossil evidence indicates that some dinosaur eggs were pigmented in green and other other colors.


Thanks for reading! This post provides a general description for this project and its underlying scientific and design concepts. We'll post updates as the planting takes hold and grows in to complete the ancient world living display.