Hi Ontario... What you're asking about is done a lot in Japan and certainly can be done here. What you need to know is when is a safe time to prune trees, and if they're deciduous, you'd do it in spring just before buds open, and if they're conifers, then you'd do it in late fall, when they've gone dormant, though you can trim foliage and small twiggy growth later in spring as well to keep things neat and finesse the shape. After that, it's mostly about what style you want to make your trees, keeping in mind that they will continue to grow, of course. One idea is to get hold of as many bonsai books as possible and look at various styles to see what's attractive for which trees, and what would be unnatural for a given species. You need to realize that most bonsai are created by chopping down larger trees, ones with good sized lower trunks, then allowing new branches to grow, encouraging new 'leaders' (the main trunk line 'branch') to grow upward by tying up a side branch against the remaining leader stub til it takes (could be 1-2 years) - done in trees that are apically dominant, those where the trunk top (apex) naturally grows higher than surrounding branches... such as firs, pines, etc. For others, like elms, the natural pattern is called 'broom' and it's a spreading rounded one, so you would concentrate more on developing ramification - the growth of many small twiggy branches, by annually cutting back on them, which usually duplicates the twigs at the cuts. You also need to get a sense of which major branches on a given tree to leave and which not to, and there are 'rules' or guidelines to help with it, based on what looks more balanced, graceful, and enhances the tree's look. Distorted, grotesque, belabored styles (including topiary - there are ways to develop "pads" on e.g. pines, that are more natural looking than lollipops) are not encouraged in bonsai, though many are created (often en masse) by sellers who think it's what people want, though they won't take the time (or lose the money!) to train each tree to its best potential and you end up with "mall-sai" or cookie-cutter trees, with exaggerated "S" bends in the trunks, rather than natural looking curves. With small bonsai (in pots) wire is often used to bend branches, slowly over time, but it's impractical in yard trees, though one could attach weights to help bring down or bend branches, as long as the tethers are carefully watched so that they never cut into the bark, but are replaced, if necessary, for the next season. Bottom branches (1-2) are often left on trees where the eventual style does not call for them, but as they help to fatten the lower trunk and add to the illusion of age, they're left on for as long as you want, and only "sacrificed" in the future when you're ready to display the tree as 'finished'. Everything I've said here is very simplified, so you do need to do plenty of reading and looking, but advantages you'll have in growing the trees will be that you don't need to repot and prune roots all the time, and that you know your trees are already suited to their environments where they're much more likely to do well. Here are a couple of good general bonsai links, if not ones that refer to yard trees... www.evergreengardenworks.com (lots of info on conifers), www.bonsai4me.com (basic bonsai starting place), plus go to www.bonsaichat.com and www.bonsainut.com for forums where you can ask more questions as you go along. Let us know how things go!

Great, thanks, this is just what I needed to get me going. Was wondering about when to trim - will do a bit this fall. Yay! Away I go.

ps I have seen the S-bends - I agree - too unnatural.