One of the most powerful and versatile tools in bonsai is grafting. It gets a bit of a bad rap as an ‘advanced technique’, but it’s surprisingly simple! True, compared to the random process of back-budding, in grafting you are assuming full control over the placement of the future branch, so you really need to think ahead carefully of what and where you’ll be going with it. But grafting adds so much flexibility and options when styling a tree, that it really is a good technique to have under your belt.
Take this juniper for example -
This is one of the junipers from the Jerusalem Botanical Gardens collection, as it was in early April 2012. Not the most auspicious of beginnings – long, empty branches with thin foliage at the tips; excessive, undirected growth; too many branches; and a general lack of impressiveness. Or in other words – a challenge!
Here’s the tree as it was a few days ago -
As you can see, a design direction was chosen for the tree, unnecessary branches removed, remaining branches trimmed hard and left to grow back, and most importantly – the tree was repotted into a much better soil mix. Repotting these trees is a masochistic adventure in itself, and you can read all about it in my earlier post on extreme repotting.
At this point in the tree’s development, one option would be to bend the upward-growing branch a bit to the left, and then start to bend the other branches in order to achieve the desired silhouette. The problems with this option is that 1) that branch is actually about 15 years old and very, very rigid; and 2) I would be able to get a nice SILHOUETTE, but I wouldn’t be able to have any STRUCTURE. The inside of the bonsai would just be a jumble of branches bending and re-bending in order to fit inside the silhouette. Not cool.
So, here’s a classic case where grafting is a great option. I can also use this opportunity to graft a different variety of juniper, and improve the foliage.
Now, there are various different types and techniques for grafting. Here, I chose to use an approach graft, which is relatively simple and fool-proof. Simple, as you can see below. And fool-proof, as both the trunk and the scion remain connected to their respective root systems until the graft takes.
So what we want to do is attach the foliage on the left, to the trunk on the right
What you’ll need is -
√ 1 pc trunk stock
√ 1 pc foliage stock
√ 1 pc chalk or marker
√ 1 really sharp knife
√ A few thumbtacks
√ Electrical tape or equivalent
√ A few pieces of wire
First thing you want to do, is mark where you’ll be attaching your graft. It really pays to take some time and consider what you’ll be doing with your future branch – how does it work with the trunk line? which way will it grow? will you be bending it? in which direction? and so on and so forth. Once you know where and how you want to place it – mark the spot. In approach grafts, you can place the shoot over the trunk, and mark out its edges.
Then, using a really sharp knife, cut out the channel where the graft shoot will go. Make sure to make the channel a bit thinner than the shoot. You want it to fit nice and tight when you’re done, and you’ll be taking a bit off the shoot later on. If you make it exactly to size, you’ll end up with a space between your channel and the shoot, which can significantly delay the graft.
You also want the channel deep enough so that the shoot is flush with the trunk. This will guarantee that the graft point is as inconspicuous as possible down the road. However, it is better to have the shoot protrude a little than have it sunk below trunk-level. If it is below trunk level, the cambium layers will not be able to touch, and the graft will either not succeed or take a very long time.
Now, all the literature on grafting always says that you have to align the cambium layers, and honestly, that always freaked me out a bit. It sounds like you have to make sure that the cells are all facing the same way or something. Truth is – it’s much simpler than that. All you have to do is make sure that they touch. The best way to do that, is to place the shoot in the channel, and then go over it with a (non-permanent) marker or a piece of chalk. Any bark that has color on it needs to stay. Any bark without color needs to come off to expose the cambium. That way, you can be sure that you’ve exposed the cambium all the way up to the level of the bark on the trunk.
Use the knife to slice just the bark off the shoot, exposing the cambium. This is where it really helps to have a very sharp knife, as otherwise you won’t be able to control the cut as well. Now you simply insert the shoot into the channel, making sure that your markings are facing upward, same as before. Take some thumbtacks (preferably with a bit of cut-paste), and place them either through the shoot, or close on either side of the channel, to secure the shoot in place. If you push the thumbtacks on either side of the channel, they will push it inward and facilitate the grafting process.
Now, all you have to do is wind some tape tightly around the graft, and you’re pretty much done. The tape does two things – it delays any drying and callusing of the exposed cambium; and it exerts pressure on the shoot. As the shoot (and trunk) grow and expand, the new layer of wood has nowhere to go except sideways, and the cambium layers of the shoot and the trunk merge. As an added measure, wind some wire tightly in several places along the graft. Where the tape is slightly elastic, the wire is sure to hold all graft elements securely in place.
And that’s really all there is to it. Here in Israel, with our charming weather and three growth periods each year (!), it doesn’t take very long for grafts to take. I think that by mid-March, I’ll be able to update on the progress of this graft.
As you can see, through a relatively simple procedure, this juniper now has a shoot growing much closer to the trunk, in the direction that I need. I can now work with the growth of this shoot, and build the structure for the future design of this tree right from the start. This, plus the improved compact foliage, will allow the tree to become a better bonsai than had I tried to bend and cram all those long branches into a compact silhouette.
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A lot of people have written and asked me when is the best time of year to graft junipers. For grafts such as these, where the scion (the grafted foliage) is still connected to its roots, the best time would be when both trees are actively growing. In my Mediterranean climate, that would be around May or June.