natural nebari

Improving the Roots On a Large Oleaster Through Air-layering

This large Elaeagnus pungens, also known as oleaster or silver berry, has great potential. It was collected about a year and a half ago from a hedgerow, has a great trunk, and has grown fast and strong, back-budding profusely after being chopped back hard at the time of collection.

large oleaster for bonsai

elaeagnus pungens after a year and a half recovery

By the way, before I get started, if you have a lot of large trees I definitely recommend investing in a hydraulic cart like the one I have here. You can find them at your local hardware store, and they go a long way towards saving your back when moving trees to work on. This tree is easily over a hundred pounds, but I only have to move it six inches from my garden onto the cart. I can roll it over to my work area, and with a few pumps of the foot pedal, I have it at just the right height to work on.

oleaster on cart

fully extended, it’s in perfect position to begin working on

Now back to the tree. When first collected, we pulled three out of the ground. A homeowner had asked to have them removed as they were redoing the landscaping

silverberry hedge

silver berry hedge at the time of collection. easily 6′ x 6′

load of elaeagnus pungens

myself after a long day of pulling trees out of the ground

chopped back oleaster

cut back hard, the tree was allowed to recover for a year and a half

Finding a tree in the wild (or urban wild, as is the case here) that is ready to drop into a pot and call a finished bonsai is beyond rare, impossible even. This tree is definitely no exception to that rule. The main issue here, the roots are absolute garbage.

oleaster bonsai roots front

a view of the roots from the front

oleaster bad base

different angle of the base

oleaster bonsai base 2

final angle, this is the worst side. no roots at all

As you can see from different angles, the base is practically unsalvageable. In the last image, there is no nebari at all! So is this fixable? Well, yes and no. A couple of options exist. If we were dead set on keeping this base, then root grafting is really your only option here. And it’s not a good one. Even as vigorous as this tree grows, to make it look natural would take forever and it may not ever achieve the desired effect. All is not lost though because there’s a better option. But it involves basically completely throwing away the bottom half of the tree. This is achieved though the air layer.

If you’ve read some of my previous articles then you understand the basic concepts of air layering, how it works, and why as well. All of those previous examples were performed on individual branches. There’s no reason the same results cannot be achieved on a single trunk as well. The procedure is the same. A ring of the outer layer of bark is stripped away to the sapwood beneath, creating a physical barrier between the roots and the rest of the tree. The results are the same as well. We are creating a totally new set of roots that the tree will use to grow and pull down nutrients created in the leaves through photosynthesis. Because the cambium and phloem is removed, the tree will be forced to create these anew.

We begin by taking a sharp knife and carefully scoring the bark in two places, completely encircling the tree. The top score will be just beneath where the new roots will form. Keep this in mind so that you have an idea where your new roots will form to create your base. After making your score, carefully peel away the bark to reveal the shiny sapwood beneath. Make sure that you don’t penetrate too far or you will damage the sapwood and no water will be carried on to the tree’s canopy from the existing roots, effectively killing the tree.

oleaster bonsai bark score

the bark is removed in a ring around the base

The next step is a personal preference, and is not absolutely necessary. I like to wet the tree and dust it with rooting hormone. This can be bought in any garden center cheaply.

oleaster air layer bonsai with rooting hormone

rooting hormone is dusted along the scored edges

Instead of wrapping the area in plastic and sphagnum moss like we did when creating the previous air layers, we will be using a plastic pot filled with our bonsai soil mix. I recommend doing this if you are able to water the tree regularly. The new roots will be growing in the same type of soil that they will be planted into permanently, so less of a transition will have to be made after they have matured and established themselves. A common plastic gardening pot is perfectly fine to use, as long as it’s big enough to encompass the tree’s base.

plastic pot

a common plastic potting container

Cut the side of the pot and remove the bottom so that the pot can encircle the base of the tree.

modified bonsai pot

the side of the pot is cut and the bottom is removed

Next, wrap the pot around the tree at the base and fill it with your bonsai soil. I used some duct tape on the side just to keep it together and prevent the soil from spilling out.

pot around bonsai tree

the pot is wrapped around the tree and taped on the side

pot with bonsai soil

fill the pot with your bonsai soil

And that’s it. Make sure to keep it watered as you water your tree. Give it a season or two, checking on the layer periodically by gently brushing back some of the soil, being careful not to damage any new roots that are forming. When the pot begins to fill with roots and they start to turn brown as they mature, the tree will be on its way to sustaining itself. Insulate the new roots during freezing weather, and keep the pot watered. Before long you will have built a brand new base for your tree, and the old base can be cut away. The new roots can be trained and placed to create a nice even nebari and it will be like a brand new tree.





  1. Scott Irwin
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