Hints and Teasers
Helpful Hints 4
by Lew Buller
Balance is important, Bare rooting your tree
Sooner or later a beginning bonsai enthusiast will hear someone say “Keep the top and the bottom of the tree in balance; if you cut off some of the foliage, cut off some of the roots.” Two questions arise: How much do you cut off of each? What happens if you get it wrong? Seldom do you get an answer to those questions.
The answer to the first question is that you never do more to either top or bottom than the other can support. The answer to the second is that if you’re lucky, the tree will make the necessary adjustments. The most important factor is the aftercare.
Take propagation from cuttings, for example. An experienced propagator will remove enough leaves from a cutting to keep the non-existent roots from being overloaded in a demand for water. Put the cuttings in the right growth medium, say perlite with 10% peat, cover the container with a plastic bag and the cuttings will take. Perlite makes it possible for the cuttings to get both water and oxygen and for roots to begin to grow. The small number of leaves provides enough carbohydrates to support new roots. Add a mister that sprays water periodically and chances of the cuttings taking increase substantially.
In the first Helpful Hints I created a root-over-rock, and showed the tree with very few roots. The foliage was not reduced. I was a bit nervous as the tree’s leaves began to turn yellow and fall off. Here it is a month later.
Imagine my pleasure when I examined the tree closely and saw signs of new leaves. The bougainvillea cascade I transplanted did the same thing. I call this process “self-balancing”: the trees are making the necessary adjustments.
How do you balance a tree? Do what is necessary to insure a healthy set of roots and the top will take care of itself. That means provide good soil and a free-draining pot appropriate to the size of the tree, along with adequate water and sun.
Bare rooting your tree
When I checked the Internet for bare rooting trees, I got a wide variety of information. It ranged from vendors wanting to sell bare root seedlings for use in bonsai, to authors who used “bare root” as a way of getting people to read information about other plants, to examples of transplanting that were bare root but with such well developed root balls that bare rooting caused no real disturbances in the development of the plant, to some bits and pieces of information on deciding to bare root. If you have time, check for yourself.
When a tree is showing signs of new growth, that is usually the time to transplant. How do you decide whether a tree can or should be bare-rooted when transplanting? First, know your tree. For example, the blue atlas cedar has very sensitive roots and in fact may die if the root crown is disturbed or planted at a different depth. Second, take into account the age of the tree. Young plants, especially seedlings, can be bare-rooted and suffer no apparent damage. Much older plants are transplanted infrequently and severe cutting back of the roots may stimulate new growth that destroys the design or makes it difficult to maintain. Then think of the environment the plant will be in. Bougainvillea can be transplanted in the spring, but they are really hot country trees and do very well if transplanted in midsummer. Think about the origin of the species you are working with and follow the natural cycle of the plant in its original environment.
Taking these factors into account, I bare root under two circumstances.
1. When the root ball is strong and healthy. Bare rooting allows fresh soil to be mixed in with all roots. Other circumstances also call for bare rooting. If an air layer results in roots that are not evenly spaced around the perimeter, I may bare root, balance the roots some, and use rooting hormone to stimulate roots in the void areas. An ice pick was used to make several holes in the live cambium at points A, B, and C and hormone was applied to the holes.
Ficus grow prodigious amounts of roots and it is necessary to bare root them to see where and how much to cut off. Since they are hot country trees, I do it in July when I transplant. Other trees have similar large roots and can withstand severe cutting. The Silk Floss Tree (chorisia speciosa) is an extremely strong top grower; all side branches die off until the tree begins to mature. At one time, mine was over 5 feet tall; I cut it down to about 2 ½ feet and divided the excess into 3 parts. They went into soil, full sun, regular water, and 2 of the 3 took. I learned they can withstand severe cuts in both trunks and roots. In 2008, the mother tree had filled the pot with one major root that clearly needed to be cut back. Here’s what it looked like after the cut. Six years later it is still alive and growing strongly, needing transplanting again.
I tried the same thing with a substantial elm that had one long root circling the bottom of the pot and had disastrous consequences. I didn’t know my tree.
2. When the root ball is weak and sickly. A bougainvillea provides an example. When I took the tree out of the pot, the soil was black and slimy and it was hard to see where roots originated. Time to bare root; not much choice. My decision was made easier by the fact that some years ago I had cut a section from a bougainvillea shoot, put it half way down in good soil, watered it, in full sun, and watched it grow both roots and leaves.
The roots on this bougainvillea originated mostly on one side. I didn’t cut any roots off; the top needed as much support as possible. Time to balance the roots at the next transplanting.
Your turn. Would you bare root this root ball? It’s a juniper, about 25 years old, and hasn’t been transplanted in 4-5 years. Planted in a mix of pumice and akadama. Showing some signs of distress.
I did not transplant it. Age was a determining factor, but also it was late in the season. I removed about 1” of soil all the way around, about ½” of soil from the bottom, and replaced it with my standard bonsai soil. Over time, I will replace all of the old mix. Right now, it takes up water well and is improving.