Hello, Been doing some reading. Here on the coast our plants are subject to constant rain 6 months of the year, so I'm thinking about blending an inorganic bonsai soil. I'm leaning towards using a vermiculite/aquarium gravel mix. I'm just hoping that someone could direct me to information about the proportions for such a mix. Simple plants, juniper, boxwood, and azaleas. My guess (and is is just a guess) would be a mix of 50/50 fir the leafy trees and 70/30 grit/vermiculite for the conifers. Does this sound about right or am I off my rocker?
Vermiculite is lousy in bonsai soil... compacts very quickly and holds water. You want Perlite, if you can stand the 'white', and you also need a little organic in there after all, and need to feed often. Azaleas need a lot of peat in their mix, no real way around it, just balance it with grit. Juniper can take a lot more grit/gravel, but still needs things like bark mulch or bits (1/8" pieces), and boxwood could use a touch of lime. There's no one-size-fits-all mix, similar ingredients in diff. proportions, but not one single mix for everything. Maybe do just a bit more reading (and see how many(!) versions there are and what's used for grit.. like turface ("Profile" at Can. Tire), crushed lava rock or brick, perlite, chicken grit from a farm feed store, etc. etc. And some have slight water holding capability (turface, or akadama if you can afford to order it online) and therefore are used with grit, not necessarily in place of it. Aq. gravel's great, but each tree needs a diff. tweak, so while it's tempting to go with one mix, it's not always the best thing for every tree.
How quickly will it break down? I know that vermiculite holds water. That is why I wanted it. The pages I was reading suggested a totally inorganic soil. No dead plant matter. It says that the two things that soil needs are free drainage and little water retention. Grit to promote free draining soil, and vermiculite to retain only enough water. My major concern is the constant rains in winter. The last paragraph on This page argues for no peat at all. I just wasn't sure what to think of it. Thanks, M.
Sorry, didn't see that you'd answered at all... You say a major concern is that it rains all the time out there (NS isn't a lot better this summer!), yet you want to use Verm. to hold water - a bit confusing. No self respecting bonsai-ist that I know ever uses vermiculite, as other components, inorganics, (plus just plain watering) will hold some water, possibly in very small amounts, but more consistently throughout. Depending on what tree you have, and local conditions, and your attention every day to a tree's needs, and availability of components, you take the basics and decide what to use in which proportions - some people believe in using straight Akadama alone for a lot of their trees (pines, but lots of others too, though not e.g. azaleas) and others prefer to add some bark, and/or chicken grit and/or aquar. gravel... there's no one mix for all trees in all climates, and no one that everyone agrees on (except the no-vermiculite one :-)!
Lol! I get your point, Rima. It's just that I've seen a lot of stuff on the net about using purely non-organic soils (such as the page I linked). I was thinking of vermiculite (because it was listed on that and other pages) to increase the water retention slightly. Even though it rains all the time I didn't want to grow in pure grit. I was looking for the proportions. This is why I checked here before actually doing it. Because the verm. is so cheap and easy to get I was hoping that using it instead of bark was possible. Clearly it is not a good idea. I guess that the totally inorganic soils that people are talking about are things like Akadama. Thanks for your help, and my trees thank you as well. Michael
