I'm tempted to elaborate, another book length essay in the back of my mind.
@MichaelS - I'm with you, I know what you are getting at.
I have been trying to learn bonsai since 1972, about 45 years, Hallmark does not make a card for this condition. I still consider myself at best intermediate level if one were to judge the quality of tree I turn out. What is the longest I kept a single tree alive? roughly 42 years in my care, then I did something stupid and accidentally killed it. Longest I've kept a JBP alive? 18 years. I'm talking trees in pots, stuff in the ground doesn't count for this conversation. What is the ''oldest in my care" tree today? Only 8 to 10 years. Because I'm a slow learner, I have replaced my collection dozens of times over the last 45 years. Usually one or two trees at a time, not usually all at once. Why? The long term horticultural aspect of understanding your trees really is difficult. Michael S is right about the importance of understanding horticulture. If you can not look at a tree and recognize its state of health, you can not correctly determine whether a bonsai technique you want to apply will hurt the tree, or worse, kill it. This is huge. I always have problems with JBP, supposedly an easy pine to grow. Why? For many years, I mistook weak growth for healthy growth. Until I took a serious look at some JBP in a mentor's collection, did I realize I was not letting my JBP have the necessary episodes of good vigorous growth. I needed to see show quality trees, in their grow out phase, not all groomed and ready for the bonsai show. Now I wait for the big, bushy fox tails of growth before I decide the JBP can be decandled this year. Not looking bushy, I know the tree will only get weaker if I do any or all those wonderful bonsai techniques the books tell you about. Recognizing whether the plant on the bench in front of you is healthy enough to handle your planned bonsai techniques is the aspect of horticulture that really needs serious study. Its taking me a lifetime to get a handle on it, and I am not confident I can accurately do it to this day. I'm still learning.
My collection is as varied and as eclectic as the encyclopedic information in my head that you occasionally get a glimpse of from my ''book length essays'' in different sub forums. Many I have only one of, but I do recognize the value in specializing, as this helps the horticulture. I also play with groups then let them go if I find they don't grow well for me. I have well over 100 sticks in pots. I do have 7 different grafted or cutting grown cultivars of cork bark JBP. I love azaleas, so I have 5 different Satsuki, dabbled with then abandoned Vireya Rhododendrons for bonsai. I found Chaenomeles flowering quinces do well in my conditions, so I have 6 or so varieties, I have a new interest, members of the blueberry family, but they are proving a difficult group to get their horticulture down. I have several species in the blueberry family, and will be getting more, the tropical blueberry relatives seem intriguing for indoor bonsai. I've learned that Japanese maples are not quite hardy enough for my climate, and require close attention in spring, my busiest time of year for non-bonsai activities, so I have abandoned Japanese maple, but have a new appreciation for the resilience of Amur maples. My collection is evolving. Right now my specialty groups are corker JBP, locally native pines, mugo, flowering quince, Satsuki, bamboo, any Diospyros species, especially American persimmon and Ginkgo in another I have multiples of. And my "dabble for fun" group is on the theme of "Eat your Bonsai", edible fruits and nuts. Have seedling batches of Chinquapin - Castanea pumila, and American hazel nut, in 2nd and 3rd growing season stage. Also Ugni, and Eugenia for indoors "eat your bonsai".
I do have too many trees, as a result, I often miss the ideal window of time for applying techniques. This means my trees are not developing as quickly as they could. Hence, my collection looks like the collection of an intermediate level artist. If I have too few trees, I tend to over work the best ones I have. Too many and sticks in pots, and they never get past that stage, they simply get bigger, and look like crap. And as life outside of bonsai changes demands on your time, it is tricky recognizing when its time to cut down, or when it is okay to go for the next "shiny object", interesting tree, or new species you want to ''check out''.
So we all have different motives for growing bonsai. We all have different amounts of time available. We get pleasure out of different aspects of the hobby, some like showing and display, some like the propagation aspect, some never care if anybody ever sees their trees, some like to teach others. I think we each should tailor our collections to give us the most of what we love to do. If you like show and display, you should buy mature trees that can be show ready in a few years or less. If we like teaching, stock in raw and intermediate levels of development should be your focus. I love propagation, I always have seed and seedlings around. Some love the act of collecting from the wild. For many, the horticulture is a meditation practice. For others, watering is a chore to be done as quickly as possible. We are all different.
Have a varied collection until you find the groups that you do well with, understand, and like the look of. Specialize in the groups that inspire you, Try ones and twos of plants outside your specialty, if you like, who knows, you may find your next botanical love. But specializing does have the distinct advantage of being able to focus in and refine both your horticultural prowess, and your bonsai technique. Specialization is good if your mind will allow you to do it. I do focus on a few groups, for long periods, often a decade or two, then I move on to something else.
I do really well with ficus, but ficus do not inspire me, so I have just one big one, and make a few cuttings now and then to share from it. It is okay to not like certain trees.
So that is maybe a third of my thoughts, but you all have lives, and I don't need to kill more time, so I will let my keyboard cool off for a while. (I can type as fast as I talk, the down side is my writing is as long winded as I am in person)
