BSF Magazine Summer 09
By: Erik Wigert
I decided to approach this article with the intent to share some tips I use to collect and develop bougainvillea stock into finished bonsai. As such, I will open this article with the assumption that all of us as Florida bonsai enthusiasts have seen, and know what a bougainvillea is. They would be very hard to miss in the landscape during our drier months when they are in full glory. Their beautiful color is certainly what enchanted me initially and continues to reward me daily when I look out at my collection.
First of all, I can say that almost any collected bougainvillea has potential to become an interesting bonsai. Granted some of us want large impressive trunks, others shohin, some need to see movement. The end result in all cases that we need to remember is however: to build a canopy that will support the colorful bracts! With that in mind lets move on to the process.
When you look at that large thorny bush in your yard, (or your neighbors yard) realize that all you need is the trunk. Disregard the tangle, and focus where the trunk emerges from the soil. Look at the trunk and make some initial choices. Remember the ratio we may have all heard: The height of the tree should be equal to or less then 6 times the diameter of the trunk. This gives us good proportion in our bonsai. With this in mind you can cut the top out of the tree after you make your mental measurements. Now, get it out of the ground. I usually expose the nebari by hand. I have seen shovels damage nice surface roots in the past. Pull back the soil, to find where the roots flare away from the trunk. Then either with a electric saw or a hand saw cut through your lateral roots, then rock the tree and dig until you can get under it to cut any tap roots. Don’t worry about losing small feeder roots or soil – these trees are tough. Ive picked up bare-root stumps at the curb on garbage day and potted them and had them survive with no problems.
The next step is to cut it back to an initial trunk line. At this point design is not critical, don’t worry where the ‘front’ is. I prune the trees for an appealing trunk line, leaving extra options for branches and alternate trunk lines.
I cut off anything lacking either movement or taper. You will grow in a new apex and branches over the next year so don’t worry! Now it needs the roots pruned further. Bare root the tree, if its not already, and cut back roots with the goal to remove anything large that may hinder you getting it into a shallow bonsai pot. Most of the time you are now left holding a ugly stump with a seemingly hopeless chance of survival. This is the process however, and the bougainvillea can handle this treatment. I prefer to do this in the warmer months, but I have carried out these steps even in December with good success. Trees are immediately planted into mica pots. These pots have excellent drainage. I use a soil mix of 1/3 Lava Rock, 1/3 Turface, 1/3 sifted pine bark. They are wired into the pots for stability and are placed in full sun directly after potting. This seems to go against repotting ethics for most tropicals, but bougainvillea do best in the sun. When they get new shoots of growth that are 4 to 8 inches in length I begin to wire them. Select your primary branches, then return later and wire the secondary growth. I defoliate each time I wire as it makes it easier to work and forces more back budding. I begin to choose a front based on how the tree sprouts. The next stage is to begin to prune for the silhouette. Transition away from your
rule book and prune the top of the tree lik e a topiary. Repeated pruning of the top of the tree will build a dense canopy of branches so at the next styling you will have more branches to work with.
Often we must remove large branches at the initial styling. It is critical to make sure water does not collect on these scars. At the first styling I do not worry though, I later come back after I have established a design and smooth the dead wood back until it is contoured and looks natural. I prefer to use the ‘King Arthur’ brand power tool. It has abrasive carbide sanding disks that work great, plus its lightweight and easy to use. Healing is very slow on Bougainvilleas. Make sure after carving the wood to be sure to treat with a preservative. I prefer ‘Minwax Wood Hardener’. Paint it on liberally to the dead wood at least once a year.
Once your tree begins to develop a shape its important to at least once a year defoliate it and assess the branch structure. Branches tend to thicken, and cross randomly if left to their own devices. Prune back and rewire as needed. You will likely find that defoliating is the most reliable way to force blooms on your tree. I time a defoliation prior to exhibitions to obtain a full canopy of blooms. If your tree shows signs of yellowing or lack of vigor its likely root bound, or the pot is retaining to much water. I keep all my large specimens in mica pots as they have extra drain holes, and switch them to ceramic pots only for exhibitions.
To Recap: The Key to developing Bougainvillea fast is to stay on top of them.
- Cut hard in the first styling, don’t waste time!
- Bare-root and repot in Bonsai soil at first styling.
- Wire first growth as soon as its long enough to set the primary branches.
- Allow a few months growth then wire again to set secondary branches.
- Then get in a pattern of ‘topiary trimming’. Work to build the silhouette of your Bonsai.
- Defoliate and prune for proper branching, then rewire every year.
- In between continue ‘topiary trimming’.
- Keep in full sun, fertilize well and use well-draining soil.