Some of the few certainties in bonsai include that you will need a tree to work with and that it will take many years to develop this tree into a bonsai. Many newbies (myself included) struggle to understand what is the best material to start off with and why, often times, folks here may suggest that a tree isn't great material to work with and that one should pass on certain material in favor of something else. So I thought I'd start a thread to help focus newbies on the material they are considering and perhaps provide a little guidance on how to look at material.
In choosing bonsai material to develop, I try to keep 2 things in mind: (i) where does this tree fit on the "bonsai timeline"; and (ii) any specific material will have both pros and cons. With respect to the first point, bonsai is very much "last in action, first in thought". Although we may refine and change our plans for a specific tree as we progress, it is helpful to have at least a general idea of the ultimate tree we want to develop early on. Then we can start to make plans for how to develop a specific piece of material into the desired ultimate bonsai. How tall will the tree be, how thick of a base do we want, where do we want movement/taper, and how will the branching look? Once we have a general idea of what we want to build, we can ask ourselves where on the bonsai timeline is this particular tree? For example, if I want a 4" trunk at the base and am considering a sapling as my potential material, I know I have many many years before I have the desired base.
A necessary corollary to the first point is that one needs to have an understanding of the bonsai development process in order to ascertain where along the timeline this tree is and whether one wants to proceed with it. While there are always exceptions to things in bonsai, building a tree from bottom up is generally an efficient way of proceeding. This means that we get our nebari set up to grow correctly and begin fattening up our trunks to get the desired base. We can then prune the tree as needed to create taper and movement. It is really only once we have this basic skeleton of the tree that we can start addressing placement of branches and begin the process of ramifying branches. Of course, one could simply purchase a more developed bonsai to get them further along the timeline, but that's not what we are discussing here. This is really a pre-bonsai discussion.
So what makes some pre-bonsai material better than others? To answer that, we need to again ask ourselves where on the timeline is this tree in relation to what I want from it? Of course, we want to start with healthy trees from reputable growers regardless of the actual material chosen. Nebari already growing radially is better than not for the simple reason that we don't need to spend the time redoing the nebari. Fatter base is better than sapling. Existing lower branching/movement and taper is better than the alternative because again we don't need to take the time to develop these as they already exist, thereby cutting the timeline down considerably. Remember, even with the head-start afforded by better pre-bonsai material, we are still in for a years' long developmental journey.
If that was all there was to choosing pre-bonsai, this would be a much easier process. Unfortunately, rare is the pre-bonsai that possesses all the desired qualities (like unicorn rare). Most of the time, we are forced to engage in a trade-off, picking the trees with the pros we want and having a plan to address the cons. For example, I personally do not enjoy working with saplings, and would much prefer a larger sized trunk. In addition to added cost, I typically pay for this choice in that I will receive a tree with sub-par nebari that is also stick-straight/no taper. It is a trade off - I am trading the time saved in growing the trunk for time to be spent improving the nebari and creating movement/taper. And I have gone the other way as well. Just yesterday, I purchased a discounted maple with a rather slim base (not even 1/2") because I was so impressed with the nebari on this little guy and will now work him into a shohin. Some people much prefer starting with a sapling so they can get the nebari growing correctly from the get-go and wire in movement before the tree is too thick. Some will ignore the nebari altogether, opting for a ground layer to create the nebari anew later in the process. There is no one right answer - rather, it's a calculus each practitioner needs to make with each tree. To be sure, there are countless quality levels of pre-bonsai that could ultimately be produced into the same quality tree. The question is only how much time and work needs to go into the trees to get them there. Simply stated, better pre-bonsai brings you further along the timeline.
To round this discussion out, when people suggest that material isn't good they typically mean one of three things: (i) the species chosen is simply not good for bonsai - Black locust is not the same kind of bonsai material as Japanese maple, for example; or (ii) the price of the prospective material is disproportionate to what you are actually receiving - you can do better elsewhere; or (iii) they may simply disagree with your timeline calculus (and that's fine - you can take it or leave it) - maybe you don't want to grow that sapling out for 15 years to get a sizable trunk, only to then start developing the tree, for example.
In choosing bonsai material to develop, I try to keep 2 things in mind: (i) where does this tree fit on the "bonsai timeline"; and (ii) any specific material will have both pros and cons. With respect to the first point, bonsai is very much "last in action, first in thought". Although we may refine and change our plans for a specific tree as we progress, it is helpful to have at least a general idea of the ultimate tree we want to develop early on. Then we can start to make plans for how to develop a specific piece of material into the desired ultimate bonsai. How tall will the tree be, how thick of a base do we want, where do we want movement/taper, and how will the branching look? Once we have a general idea of what we want to build, we can ask ourselves where on the bonsai timeline is this particular tree? For example, if I want a 4" trunk at the base and am considering a sapling as my potential material, I know I have many many years before I have the desired base.
A necessary corollary to the first point is that one needs to have an understanding of the bonsai development process in order to ascertain where along the timeline this tree is and whether one wants to proceed with it. While there are always exceptions to things in bonsai, building a tree from bottom up is generally an efficient way of proceeding. This means that we get our nebari set up to grow correctly and begin fattening up our trunks to get the desired base. We can then prune the tree as needed to create taper and movement. It is really only once we have this basic skeleton of the tree that we can start addressing placement of branches and begin the process of ramifying branches. Of course, one could simply purchase a more developed bonsai to get them further along the timeline, but that's not what we are discussing here. This is really a pre-bonsai discussion.
So what makes some pre-bonsai material better than others? To answer that, we need to again ask ourselves where on the timeline is this tree in relation to what I want from it? Of course, we want to start with healthy trees from reputable growers regardless of the actual material chosen. Nebari already growing radially is better than not for the simple reason that we don't need to spend the time redoing the nebari. Fatter base is better than sapling. Existing lower branching/movement and taper is better than the alternative because again we don't need to take the time to develop these as they already exist, thereby cutting the timeline down considerably. Remember, even with the head-start afforded by better pre-bonsai material, we are still in for a years' long developmental journey.
If that was all there was to choosing pre-bonsai, this would be a much easier process. Unfortunately, rare is the pre-bonsai that possesses all the desired qualities (like unicorn rare). Most of the time, we are forced to engage in a trade-off, picking the trees with the pros we want and having a plan to address the cons. For example, I personally do not enjoy working with saplings, and would much prefer a larger sized trunk. In addition to added cost, I typically pay for this choice in that I will receive a tree with sub-par nebari that is also stick-straight/no taper. It is a trade off - I am trading the time saved in growing the trunk for time to be spent improving the nebari and creating movement/taper. And I have gone the other way as well. Just yesterday, I purchased a discounted maple with a rather slim base (not even 1/2") because I was so impressed with the nebari on this little guy and will now work him into a shohin. Some people much prefer starting with a sapling so they can get the nebari growing correctly from the get-go and wire in movement before the tree is too thick. Some will ignore the nebari altogether, opting for a ground layer to create the nebari anew later in the process. There is no one right answer - rather, it's a calculus each practitioner needs to make with each tree. To be sure, there are countless quality levels of pre-bonsai that could ultimately be produced into the same quality tree. The question is only how much time and work needs to go into the trees to get them there. Simply stated, better pre-bonsai brings you further along the timeline.
To round this discussion out, when people suggest that material isn't good they typically mean one of three things: (i) the species chosen is simply not good for bonsai - Black locust is not the same kind of bonsai material as Japanese maple, for example; or (ii) the price of the prospective material is disproportionate to what you are actually receiving - you can do better elsewhere; or (iii) they may simply disagree with your timeline calculus (and that's fine - you can take it or leave it) - maybe you don't want to grow that sapling out for 15 years to get a sizable trunk, only to then start developing the tree, for example.