by Lew Buller
San Diego, California USA
A Ficus benjamina growing in the ground can reach 30, 60 or 90 feet, depending on which authority you consult. The explanation lies in the humidity surrounding the tree in nature. 30 feetthat’s California size; Southern California, with its dry desert or near-desert conditions provides the warm temperatures the tree needs. You might guess that when it reaches 60 feet, it is in a more humid locationFlorida. Really humid conditions in India during monsoon season or in Brazil with rain forest conditions allow the tree to reach 90 feet. That humidity induces aerial roots to form; when they reach the ground they become supporting trunks, eventually self-grafting into one massive trunk.
The photo of aerial roots was taken outside the San Juan hotel in Puerto Rico, where Bonsai Clubs International held a convention some years ago. My wife, standing beside the tree, gives some idea of the size of the tree. The tree has been blown over twice, once after that convention. The hotel simply stands the tree back up and it goes on growing as if nothing had happened.
Bonsai are made with the species Ficus benjamina and also with cultivars. Because leaves on the benjamina range from 2 ½ to 5 inches long, a sizeable trunk is needed for good proportions. Getting such a trunk usually involves cutting a well-developed trunk down to the height desired and then re-growing a canopy. Even medium-sized cuts heal slowly and poorly; large cuts may never heal. Tried it once; didn’t like it. I wanted a miniature cultivar and found it at a local nursery; its name is Ficus benjamina ‘Little Lucy’.
‘Little Lucy’ grows very slowly; I estimate the trees in my saikei are 17-18 years old; the tallest is still only 19 inches tall. Without trimming, it might have reached 28-30 inches. In general, the shorter the tree’s natural height, the slower it grows. One theory is that the genetics that cause the tree to be small also affect its growth rate. A second reason is that it takes a large leaf area to develop a large trunk; the ‘Little Lucy’ has a comparatively small leaf area. The photo of leaves compares the leaf size of the species to that of the cultivar.
For design purposes, it is still necessary to remove branches on the miniature cultivars, but the small wounds heal much better. A healthy tree puts out latex almost immediately and seals the wound, although Elmer’s carpenter glue also works well. If a larger wound rots at the center, it does not kill the tree but rather adds to its natural appearance.
The definition of a succulent is a plant that stores water in its branches, trunk, and/or roots; ficus do this and also store water in the leaves. Cut a leaf in two and it will bleed latex almost immediately. Cutting all leaves in two results in smaller new leaves; the old leaves are unable to produce enough carbohydrates to develop large new leaves. The latex that bleeds from all cuts marks the benjamina as a member of the rubber tree family. The practical implication is that tools get sticky from the latex and so may your hands. Some people are allergic to the latex, so use gloves if you have allergies. The latex is poisonous, so don’t lick your fingers.
The succulent-like characteristics include a waxy, shiny upper leaf surface that leads to retention rather than evaporation of moisture. The tree has adapted to monsoonal conditions, dropping leaves during prolonged dry spells. It may also drop leaves as a result of over-watering. The photo of the Ficus nerifolia (salicaria) branches with new leaves is of a tree recovering from a near-drowning. The nerifolia (salicaria) dropped all its leaves and appeared to be dying, so I quit watering it. The falling leaves were yellow and that should have been a clue to the over watering. Falling green leaves would indicate under watering. When I scratched the bark, the cambium was still green underneath so I didn’t throw it away. After a period of drying out, it began to grow new leaves at the tips of the branches and from small pink eruptions on the sides of the branches. The new leaves are light pink, turning green as they mature.
Give the benjamina (and the nerifolia/salicaria) moderate amounts of water during the warm season and just enough to keep it from drying out during the rest of the year. If you can feel moisture one inch below the soil surface, that is enough.
In nature, benjamina have symmetrical rounded canopies. A 60-feet tall tree may have a 70-foot wide canopy. While most trees can be designed in the classic pine style, I prefer mine to look as natural as possible. Check out the shape of the canopy before the last trim. The tree was taller than it was wide, so I took about 4 inches from the top, knowing that it would re-grow soon enough.
The cuttings went into a mixture of peat and perlite which could be watered heavily without water retention. They were kept in a jury-rigged greenhouse, a translucent garbage bag draped over a make-shift frame, and the following spring, were set out in separate 4-inch plastic pots. It’s OK to leave some of the peat and perlite for drainage around the roots because the cuttings will die if overwatered. Cutting the top back strongly will usually stimulate growth lower on the trunk. Cut back to a point above a leaf node, leaving ½ - ¾ inches to die back. The dead stub is easily removed later. Commercial growers sometimes use meristematic propagation (cell cloning) rather than cuttings.
The ‘Little Lucy’ clump has self-grafted at the base. Ficus benjamina self-graft so easily that nurseries braid young trunks and sell them, knowing the trees will eventually fuse completely and leave an interesting pattern of lines and protrusions in the bark. If the roots in the photo look as if they have been cut off sharply where they enter the soil, that’s because they have been. Roots can and do fill a pot; they contain the plant’s reserves and will become very large. In warm weather when you transplant, make large cuts on the roots parallel to the bottom of the pot, tie the tree in and give it proper aftercare, and it will never know the difference. By all means, use sharp tools on a Ficus; the roots are even stringier than the trunk and tear easily if dull tools are used. A lesson learned the hard way.
Benjamina roots also adhere to stones, making it and its cultivars excellent candidates for the root-over-rock form. At the time of its transplanting to the present pot, (its feet were very cramped in the old pot) the roots had grown in and around the stones so well that the whole thing was transplanted in one piece.
‘Little Lucy’ responds well to the clip-and-grow method. A new leaf will grow from the axillary bud at the base of the last leaf on the branch, and you can use this knowledge to prune directionally, cutting just above a leaf which has an axillary bud pointing in the right direction. It wire marks easily; so if I wire, I use aluminum wire and wrap it very loosely. If there are any signs of wire marks, remove the wire immediately because wire marks never heal over smoothly. I cut pieces of chopsticks and used them to prop the trunks apart so there would not be any crossing trunks. Crossing branches toward the top appear in nature and are usually hidden by the canopy.
Several of the ‘Little Lucy’ trunks were tied down to the edge of the pot to create the angles and separation I wanted. Well padded tie-downs are great. I also use them on my Ficus microcarpa (retusa) to help create low, spreading branches. The tie downs don’t have to be pretty; they just have to work. These are pieces of old telephone wire, attached to a copper wire tied around the pot just below the rim.
The white pumice on top of the soil accepts water easily and keeps the underlying soil from hardening due to watering. It also provides enough humidity to allow some aerial roots to form. My soil mix is standard for San Diego; one-third river sand, one-third potting soil, and one third agricultural pumice. It drains well, but if the tree were in the ground it would like a richer soil. The soil in the bonsai mix retains fertilizer and brings it in contact with the roots. The tree responds best to frequent light feedings so growth is steady. Heavy fertilizing does not lead to faster growth and may result in fertilizer burn.
The deep green color of the mature leaves is a result of growing the trees in substantial shade. Ficus take about half as much light as a black pine, and this makes it possible to grow them indoors. Create a spot with limited sunlight and a way to provide humidity and the tree will flourish. Like orchids, they have little tolerance for changes in position; move them carefully and even then leaves may drop.
You may also see yellow curled leaves with brown spots on them. These are thrips and can be dealt with easily by removing the infected leaves and destroying them. Mostly it is my ficus microcarpa that suffers from thrips; the ‘Little Lucy’ and the nerifolia/salicaria on the same bench with the microcarpa seldom show any signs of infestation. Generally, my ficus all seem to be free of pests and diseases.
After 17-18 years of growing here’s what ‘Little Lucy’ looks like now.
Lew Buller has been doing original and creative bonsai and Saikei for many years. He has authored numerous articles in the major bonsai publications as well as authoring several books. His Saikei book, Saikei and Art: Miniature Landscapes is the definitive english language book on the subject. He also co-authored a book on Vietnamese bonsai called Mountains in the Sea: The Vietnamese Miniature Landscape Art of Hon Non Bo.
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Thanks to Lew for sharing his knowledge with us.