This instructable shows my first real project in bonsai. The techniques used were learned through research in various book sources and with a visit to the Wichita Bonsai Club's monthly meeting. I open myself up to any criticism from people with more experience.
This project takes a landscaping bush purchased at Lowes for $16.98 and starts its training as a bonsai specimen in what's known as a "training box" to start to make the roots the right shape for a more shallow pot. It involves building the box itself, pruning (with root pruning), and potting the tree.
This bonsai will be kept outside year round unless there is some extreme in weather. According to many I've spoken to about bonsai the most common mistake is to try to get a plant which is meant for outdoors to live inside. There are some tropical species which can tolerate this, but most evergreen and deciduous trees need humidity, lots of light, and seasonal weather changes which are nearly impossible to replicate indoors.
I wanted to plug a couple of sites which have helped me out considerably:
The Helpful Gardener - Bonsai Forum:
- Very good (free) forum which has always given me quick, well informed responses from cool people.
Wichita Bonsai Club
"The Rules of Bonsai" - A set of rules that everyone interested in bonsai should read.
Step 1: Materials
I went to Lowes which is just starting to get in some of it's shrubbery for the early spring. Out of about 30 plants I chose this one as it had a pretty thick trunk, good cold tolerance (reportedly to -40 to -50 degrees F when planted in the ground), and wasn't too expensive. As for species the tree is a Prunus x Cistena or Purpleleaf Sand Cherry. It looks like it's a flowering bush with relatively small purple leaves. It is currently just starting to bud and was in a 2.5 gallon pot when purchased.
I plan to be relatively brief on the construction of the box itself, but I'll elaborate on the drainage and wiring aspects.
The materials used for the box were (mostly improvised):
A piece of poplar I had sitting around which was 9.5 inches wide by 5/8th's inches thick.
- this thickness was not necessary but only used as I had it lying around.
A long piece of pine which was 1 inch by 6 inches (which is actually 3/4ths inches x 5.5 inches)
A good belt sander (always important to try to cover my mistakes with)
A miter saw deep enough to cut a 5.5 inch width board.
A hand saw for the long cut at the base.
A drill press with a 3/4th inch hole boring bit.
An electric drill/screw driver with about ten 2.5 inch deck screws
A good pair of hand hedge clippers.
A little sand paper for hand sanding
For the potting itself:
Pea gravel purchased at Lowes for about $4.00
One gallon of all-purpose (open to debate) Bonsai soil purchased at a local nursery which specializes in bonsai for $6.50. It looks like it is mostly composted of akadama and peat.
Some of the mulchy soil removed from around the roots.
A piece of aluminum gutter guard mesh
18 gauge copper wire
Step 2: The Box
The size of the box is something of an estimation based on the size of your specimen. I like to think in terms of "supply and demand" when thinking of root pruning (again noting my gross inexperience). The roots are the "supply" and the branches/buds/leaves/flowers are the "demand". When you root prune you decrease the supply so the top parts need to be pruned as well. It's a good idea to do this just as the plant is coming out of dormancy (in my case in mid March). Species can vary on this point though so do some internet research on your particular plant. Also, when thinking of the box size consider the fact that about the bottom third of the pot will be filled with pea gravel in order to promote good drainage. For my plant, which was root bound in a 2.5 gallon pot, I ended up making a box
9 inches x 11 inches x 5.5 inches.
I made it this large in order to be on the conservative side due to lack of hands on experience and I'm happy with the size now that the project is complete. All bonsai don't have to fit into those tiny pots you associate with bonsai. Bonsai specialty nurseries have pots as large as 3'x1.5'x1' and larger in stock. I have also read that you don't have to be quite so careful about watering larger plants. Sounds good to me!
In terms of woodworking I did the long cut for the bottom piece with a hand saw (which turned out pretty terrible) and learned the value of a good belt sander to clean up the cut. The remainder of the cuts were done on my 10 inch miter (chop) saw. I put two 2.5 inch deck screws in between each board with six total on each side. Pilot holes help a lot with keeping the wood from splitting. For the drainage holes I used a 3/4ths inch wood bit in my drill press and cut through. In retrospect I may have put some smaller holes in the corners. Drainage is very important to bonsai and roots don't like to be drenched in water for too long a period or they can literally drown and rot. I decided not to put any kind of finish on it as I don't mind the fact that the wood absorbs water. Since then it has warped a little, but I don't mind it. I chose not to use treated lumber as I didn't want my plant exposed to the arsenic which they use. I used my belt sander to clean up all the uneven edges and smooth them out. I put on two feet as you can see in the picture in order to facilitate drainage.
Step 3: Drainage
The six holes in the bottom of the box should be enough, but you don't want all the dirt/pea gravel washing out. So next I found some aluminum gutter screening (galvanized steel may have worked, but I was afraid of the possibility of rust). Relatively firm plastic mesh is also sometimes used. I wired them into place with copper wire as you can see in the picture.
Each piece of wire goes in a U shape through the top and is bent over on the sides to keep it in place.
Two more U shapes of longer wire go up from the bottom in order to wire the tree into the pot.
Drainage is also promoted by putting cleats (feet) on the bottom of the box so the holes will be suspended in the air.
Step 4: Pruning and Root Pruning
When pruning the branches keep in mind the shape your trying to achieve. Some bonsai resources say that you should prune the branches back to two buds. When pruning leave at least a centimeter past the bud as the cut end tends to "die back" a little. If cutting branches from the trunk try to cut it back as close to the trunk as possible (some books even say to the point of making a concave surface that can heal over)
When I cut the pot away from the plant I teased as much dirt out of the roots as I could and tried to comb them out with my fingers. Traditionally a chopstick is used to weedle out as much dirt as possible. Shaking the plant also does wonders. Of course, try to put as little trauma on the roots as possible.
The picture shows something which I was very surprised by. The tree appears to have been potted deep in the pot with it's original root system almost becoming secondary. There was a large group of small fibrous roots (the kind you want for bonsai), then a small section of trunk, then what appear to be the roots from when the plant was in the ground. It looks like much of my work was done for me in terms of training the roots! I took a hacksaw and cut off the trunk at the base of the higher root system. I also pruned back a few of the longer/thicker roots which on the top half. I don't know if this root configuration a common thing with nursery plants, but it was ideal in this case.
Step 5: Potting in Layers and Wiring
Make sure your "tie down" wires are in place before adding the pea gravel. It is nice to have everything assembled before potting in order to have the roots exposed to the sun/air as little as possible. Of course there is no need to hurry too much if the roots are kept moist. Fill the bottom third or so of the box with pea gravel. I washed the gravel in a bucket first as it was dirty.
Next cover the gravel with some bonsai dirt in order to get it completely covered. Place the tree in and cover the roots with more bonsai dirt. The wires should come up through the roots at this point so you can tie the tree down. You will want the base of the trunk itself out of the dirt so plan accordingly. Try to work some dirt into the spaces between the roots. Once the tree is in place pull the wires taut (check underneath to make sure they are as it can be tricky) then twist the ends together to be tight enough to hold the tree in place, but not putting much pressure on the roots or trunk. I just put the ends of the wires back down into the tree under the dirt. Fill the pot up with more dirt and water the plant. This will work some of the dirt into the root system. After watering top up the dirt and water again. The dirt is likely dried out so it will need a couple of waterings about ten minutes apart in order to really get it soaked. You can also immerse the whole box in water if you have that big a bucket available.
I took a little of the mulchy dirt from the original pot and put it over the top. I feel this will help with keeping the bonsai soil moist, but not soggy. I kept the mulch away from the base of the tree itself. (this step open for debate)
Step 6: Long Term Care
It's been about a week now and I am pretty happy with the results. The plant has started to set on leaves and it's flower buds have started to open. It is important to keep a good balance with watering. Too much watering can cause root rot, but letting a plant become bone dry will kill it in one day or less. For this size it will probably take a day or two between waterings, but for smaller sizes you have to check the plant at least a couple times a day by digging a finger into the top of the soil and seeing if it's moist underneath. You shouldn't water if the plant is still wet on the surface. Wait until the surface dried out and the pot isn't as heavy as it generally is after you water. It's not about the quantity of water used, but the frequency of deep waterings. You want to give the soil all it will absorb then leave it until it dries out an appropriate amount. I am sure this is an experience thing and I plan on keeping pretty close tabs on it until I get a good feel for it.
The tree doesn't need fertilizing if you just root pruned it for at least a month, but it is a good idea to use some fertilizer later on. Specialized bonsai fertilizers exist, but I have heard of people crushing up extended release tree spikes and sprinkling it on the top of the soil in order to have a little fertilizer leech in each time it's watered.
Ultimately this plant will be in a ceramic pot, but I will probably let it stay in this one for about a year to let it get use to it's new local.
Thanks for reading! If anyone has any suggestions please leave a comment.
Step 7: Constructive Criticism
Here are a few points given by people with much more experience with bonsai than I:
1.) One source said that it has been largely disproven that using gravel on the bottom of the pot improves drainage as the water's surface tension keeps the water on the smaller particles above the pebbles. It is thought that a homogeneous (all particles approximately the same size) medium is best for air flow and drainage.
2.) The box easily could have been shallower. Especially if the pebble layer was removed.
3.) The box could use slats over the bottom (with more mesh) which would be much easier to construct and probably provide better drainage. The pot definitely could have more holes in the bottom especially in the corners.
4.) Bonsai "soil" rarely contains any actual soil at all but is rather composed of things such as peat or clay granules. Some options mentioned online include NAPA auto part #8822 or MVP Turface. There is a lot of debate online about soil. Most seem to agree that most of the medium should be some sort of inorganic aggregate. Google it and you'll find some opinions.
Step 8: Progress
Here I will post comments/pictures about this particular tree's progress.
These first 3 pictures were taken April 2nd, 2009.
This tree is now dormant after a summer where it lost most of it's leaves. It has been something of a learning experience and I thought I'd fill everyone in. It has set on buds so I am hopeful it will come back strong in the spring.
I re-potted it in late spring when, after more research, I realized the soil contained too many fine particles and therefore did not provide enough drainage. I have since used a soil which is composed primarily of a diatomaceous earth product which is sold at NAPA auto parts in 40# bags as a garage floor absorbent. I sift the material through a 1/8th inch sieve and add some bark of similar sizes. This has worked well for all of my other trees so far.
I will post more in the spring when/if it comes back in force in it's new soil.
The box/pot itself has warped a little with so much watering. Make sure to use plenty of screws to keep it together. I will probably change it to a new pot in the spring.
The tree has begun to put forth new buds and appears to have survived the winter. I re-potted it into a bonsai pot (pictures to be added soon). I have high hopes for it, but I may not let it flower too much this year in order to let it establish itself in the new pot more easily.
I have potted another nursery stock plant into the box (which split at the base and has undergone significant repairs). The new plant in the box is a bittersweet bush (some classify it as a vine).
By the way the nursery stock is just starting to come into big box stores like Lowes and Home Depot. I like to hunt through it early and find those interesting trunks.
Step 9: Spring 2010
ADDED April 5, 2010:
The first flower opened today! I removed a number of buds to save the plants energy, but I will still let a few bloom. The picture says it all. I also have re-potted it into a fairly large pot. These pots are available at Lowes as the bottom half of an African Violet pot ("self watering"). I actually drilled holes in the bottom with an abrasive carbon steel drill which is designed for ceramic. Enjoy the pictures!
Eunix made it!