If you want to learn how to design good bonsai trees, selecting the material to work on is your first, and arguably most important, task. The ultimate potential for quality in a bonsai tree is dependent upon your initial material selection. Without a good starting point, you're either forcing yourself into a many-years-long development stage or you'll find that your tree will never be able to reach a high level as a bonsai.
If you're new to bonsai, working with junipers can help you understand an arc of development from start to finish. Producing a juniper bonsai from untrained material is a good example of the bonsai process. While the process does differ depending on the species of your material, junipers are one of the classic and best-understood species, making them particularly well-suited to beginners.
Below is a list of four things you should look for in juniper material. This list does overlap partially with other species, so it's a good starting point in general:
1. Trunk proportions – the trunk should have enough girth compared to the tree's height to make a nice composition.
2. Trunk movement – for most junipers, the more movement the better. Chinese junipers (shimpaku) are typically very sinuous and move a lot, while Needle junipers typically have much more upright trunks with stiff movement.
3. Trunk twists – look for gentle twists and turns that keep your eyes interested [and not a barber pole effect]. Particularly for Chinese juniper and junipers native to the United States, a twist in the trunk is what makes the composition interesting.
4. Deadwood and lifelines on the trunk – the contrast between the deadwood and the lifeline on a juniper can be quite dramatic. Look for a trunk that has some age, and is irregular in cross section.
Did you notice that this list is focused on the tree trunk? That's because there's nothing else to worry about in your initial selection of juniper material because everything else can be fixed. Nebari (visible roots) are considered an accessory rather than a necessity. You can fix branch issues with grafting, bending, or both.
Is this a good piece of material? It’s got some movement, some deadwood, some taper. But ultimately it’s somewhat lackluster. There's little in the way of age showing in the composition and the proportions are off. Note the grafts that will be used to make this a much smaller tree.
Junipers collected from the wild tend to be older and large, and they're typically better for use as medium or large bonsai. Nursery grown material is often better for developing small bonsai. Whether you plan to work with a quality piece of nursery stock, or a collected wild juniper trunk, keep those four tips in mind when selecting material. Be picky, look for unusual features; and pick up a few trees so you can try different approaches.
Is this a good juniper to work on? It’s got some movement, some deadwood, but there isn’t much of a twist, and the taper isn’t so great. It could still be a good tree with the right work, but it might not be the best choice for a beginner.
A nice small Rocky Mountain Juniper trunk with a nice ribbon shape and some good deadwood. This is a great tree to work on.
If you're interested in growing your own trunk, keep in mind that will on average take you much longer to develop a bonsai from scratch than from a tree with an established trunk. And there are some really good junipers available that were grown from scratch or field grown. Since it takes much more skill to create a composition entirely from scratch than it does to adapt a good trunk to your vision, I recommend that true beginners start with a tree that already has an established trunk. Successfully design that tree into a good bonsai, then dive deeper into bonsai by developing a tree from scratch!