Category Archives: Aerial root

Taking a tree apart to improve it

This is a young rooted cutting of Ficus natalensis but the two roots as indicated did not look right to my eyes. So I split the tree and allowed it to sprout back. I like the two new pieces and with more growth I think each may work out to be a reasonable bonsai tree.

Ficus natalensis, rooted cutting, with arrows showing the roots that I did not like

The small root on the right sprouted out

The small root sprout has been potted up and will be allowed to grow to develop an apex

The larger piece will need more development but I like it better now

Aerial roots

Aerial roots grow faster than the trunk. A fact to keep in mind as you design and change your bonsai over time. I am not sure why the aerials grow faster but it seems that they do.

2016, aerials are much larger

2012, aerials are pretty small at the start

Thickening the trunk of a bonsai

Ficus virens with a nice thick lower trunk

There are several ways to thicken the trunk of a bonsai. One way is to take aerials that are near the trunk and pull them over to touch the trunk and hold them tightly in place. Over time the aerials will fuse to the trunk enlarging it, as well as creating improved surface rootage/nebari.

Three or four years ago the same Ficus has small aerial on either side of the trunk. They are pulled close to the trunk and held in position

Aerials are now fused to the base, increase the taper and thickeness of the lower trunk

Slave branches

Slave branches are used to thicken a bonsai trunk or even branch. By allowing wild and untrimmed growth of these branches the trunk or branch can be thickened.

Once the thickening is done the slave branch can be removed or trimmed back.

Wild and untrimmed growth to thicken this branch on a Ficus natalensis/thonningii complex bonsai

The branch has been shortened back once it has the proper thickness but needs secondary and tertiary branches to be developed

The branch thus thickened, as in this case, now has a proper thickness but will need more work to ramify it and develop secondary and tertiary branches. This can be done with repeated nipping out of buds and defoliation techniques.

Aerial roots are kept on this branch as they speed branch thickening

Aerial roots and growth

Aerial roots are one of the most unique and wonderful features of figs. Aerial roots start out as small fine filaments from the trunk or branches and grow down to the soil. Once rooted into the soil they thicken and can become as thick or thicker than the trunk or branch from which they originated.

Growth of the aerial is faster than growth of the trunk. Designs utilizing aerials may need to be adjusted over time to compensate for the aerials growth.

Ficus virens with aerial on the left side of the trunk, 2016

The same aerial on the left side of the trunk, 2013.

Creating a bonsai from a cutting

Taking cuttings is one of the best ways to start a bonsai tree. In this example a cutting of Ficus ‘Mystery’ was taken. It was a long straight piece of stem with several aerial roots. A cutting taken with aerial roots is almost guaranteed to root.

In this case the cutting rooted successfully and several years later the bonsai created was an attractive semi-cascade tree.

I take cuttings regularly and place them in bonsai soil and enclose the pot and cutting in a plastic bag to keep the humidity high. The bag is kept out of direct sunlight but in good bright light. Open the bat and water the soil as needed to keep the soil from getting dry but do not keep the soil totally full of water.

The bonsai created from section 4 of the photograph below

Section 4 with its aerial roots was taken as a cutting

Not behaving for me

Ficus burtt-davyi can be a difficult bonsai subject. Sometimes it just won’t grow properly. This tree has been a problem for me over many years.

It has just not been vigorous and I have had to consider discarding it or perhaps re-styling it. My decision was to get radical and to cut the tree in half. One part will become a slant or windswept while the top portion with only one root was secured on a rock to justify its poor root system. Time will tell if I can bring these two to a satisfactory bonsai design.

The overall vigor of the tree may respond to less water, coarser soil and allowing it to rest during the shorter days of winter. Time will tell.

Several years back the tree was not looking its best and I just did not care for the design

The tree was cut in half

The bottom half was planted as a separate tree

The top half was totally fine living just on its one aerial root. This was planted on the rock to deal with the one-sided root of this tree.

Moving An Aerial Root

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Aerial roots are one of the very useful and impressive features of some fig trees. As with other design elements of a bonsai the aerials must augment the overall design scheme.

In this Ficus virens the aerial root crosses across the trunk and in addition it gives the appearance of a reverse taper to the trunk of this tree. It could be removed or a better option is to move it to the other side of the trunk and use it to improve the taper of the trunk.

The aerial crosses the trunk

Closer view of the crossing aerial

A chisel is used to separate the root from its adherence to the trunk

The aerial is repositioned to the right side of the trunk

Close view showing moss added to the base of the aerial to help promote new hair roots to form

Young root emerging after only two weeks

The moved aerial is wrapped with sphagnum moss and placed into the soil. Within two weeks a new hair root is already formed. The repositioned aerial is now a permanent fixture of the design.

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