"Adequate indirect sunlight" - not achievable for two reasons. Indirect implies the need for less than full sunlight, but just being indoors, even at a window, is "indirect" to a plant, and is therefore inadequate, so giving less than the fullest possible and direct sun exposure indoors is not really enough to begin with for most plants except for the odd house plant that adapts, though may not thrive. Trees, unless hardcore 'understory' (always living in the shadow of larger ones directly above them) trees, need full sun all day, though of course there are limits when it comes to native (to a certain environment/climate) and non-native. In other words putting an oak or elm tree in the hot and unrelenting sun of a southern desert 24/7 probably won't produce a happy tree, but in any more northern, temperate and varied climate unless SO far north (zone 3 and under) that temperatures make it uninhabitable for the species, would be fine. You are likely in zone 6, BTW, though you haven't specified it in your ID line (which would help everyone to help you before even reading your notes). While a C.elm (Ulmus parvifolia) might not do well in a Minnesota winter with no protection, in a small pot, certainly it will manage where you live if you give it proper care, i.e. the pot sunk (to the rim) in a large container of mulch from Dec. onward, with an inch or 2 of mulch on top, possibly in an unheated porch or shed, but not necessarily (and snow is a great insulator and allows natural watering during short term thaws - you don't want to water once the soil freezes hard yourself). If you can't give it that kind of protection when temps go below 15-20 F. (e.g. overnights in Jan.) then you could bring it inside for 2-3 days (no more) at a time - it'll remain dormant that long - or at least for the nights, to the coolest part of your house. But the only people who'll tell you it will be happy indoors are probably trying to sell you one (and couldn't care less what happens afterward) or are just ignorant. Short term survival is one thing, after all, thriving is something else.

Bonsai soils are more about the physics of the soil than they are about what material the particulates are mad from. In most cases, we avoid peat because it is small enough that it collects in macro-pores, turning them into micro-pores that hold water instead of air. In my estimation, compost is worse than peat because it holds water tighter and its water release rate is slower. Plus, peat and compost break down too quickly to be of value in most soils for bonsai. Particles of a uniform size and shape will yield best drainage. Experiment: In a clear bottle, add a hundred or so large marbles - the boulder type, twice as large as a regular marble. These fill a 2 qt clear container and represents a soil with uniform size particulates and plenty of air spaces, a beautiful thing, this soil. Then, take a quart of BBs, dump it on top of the marbles and give it a little shake. The BBs find their way into the large pore spaces, but still fit handily into the "full" bottle. Then, pour a quart of sand (you can substitute the word peat or compost for sand here, too) into the "full" bottle. The sand filters down, clogging the remaining air pores and making the soil a terrible choice for plants. Sand is death to aeration and how did I get 4 qts of soil in a 2 qt bottle? By jamming small particulates into my air-holding macro-pores. You can build a wide variety of soils if you have a few things on hand. A porous mineral product that holds air, moisture, and nutrients - like Turface, Haydite, akadama, pumice, others. An irregularly shaped mineral product, preferably with rough or jagged edges that doesn't hold air or water - crushed granite or large silica (almost BB size) is good here, and an organic component in a suitable size that will resist rapid breakdown by soil organisms. We often use conifer bark to fill this requirement because the combination of a high % of lignin and suberin (in the bark) makes it difficult for micro-organisms to cleave hydrocarbon chains and destroy the structure of the organic part of your soil. I can't think of anything I grow in bonsai soil (houseplants too) that I use more than a 1/3 organic component on. I usually keep a large amount of soil that is 1/3 each of Turface, crushed granite (grower grit), and screened fir bark. I amend this basic mix as needed. Your mix may vary & use other ingredients, but this one won't be too far from what will work well for you. I grow most deciduous plants in the equal parts mix. Pines & junipers I use up to 90% inorganics in the soil. I even have a few plants that are perfectly happy in 100% Turface. Experiment, but don't be tempted to compromise your soil mix too much to simply extend intervals between watering - your plants will pay. Al

Clay is the LAST thing you want in bonsai soil. You need porous, large particle stuff, small bark mulch, grit (decomposed granite) and/or that small aquarium gravel (unpainted), etc. that helps the mix drain fast, so trees don;t get root rot sitting in a little pot with a small drain hole. Clay will clog everything up and compact the mix, and then turn to concrete if allowed to dry at all, and your trees will die. You need to do some reading and there's a lot of info. on the net and in bonsai bks.

First, if you haven't worked out your soil issues and gained an understanding of how to put a serviceable soil together, you really never got started at bonsai. In order to be proficient and stave off enough frustration to allow yourself to keep going, understanding soils and having enough working knowledge of (plant) physiology under your belt so you can keep your plants alive are prerequisites. You can use screened floor dry from NAPA stores, part #8822, as a substitute for Turface. Make sure your 'grit' isn't from crushed shellfish, and your ingredients are the right size. You're sure you can't get Turface locally? Where do you live? Al Here is a link that might be useful: Learn more about soils by clicking me!