My guess (without much information about this particular case), would be soil moisture issues. A small tree of that size needs to be watered at least once per day during hot weather. Temperatures in black pots, without partial shade (you didn't mention if it had that) can get very, very hot and cook roots in no time. Unless you have a very good sense of how much moisture you potting medium has at various times, you'll need to check with a finger poked down a couple of inches into the medium (you can't judge at all by surface moisture). Although moisture issues are almost certainly involved, other factors could be contributing. There are lots of variable we don't know. An example is the composition of your potting medium. I don't know what "organic" soil is all about. It looks like maybe you have at least a little decomposed bark fines in there (which is good), but that's about all I can tell. Sand is unnecessary in most potting mixes and can be good or bad depending on what type of sand it is, how much there is, and the composition of the rest of the mix. If your medium is comprised partially or mainly of "dirt", that may be a problem. Planting medium in pots has specific requirements that are often unobtainable by using plain ol' dirt. If you are still looking for more info, I would suggest placing a post in the Trees Forum and include as much detail as possible. Give us information about what, how, and when you've done things, etc.

I think you are going to have to decide whether you want to grow this tree as an outdoor specimen tree or a bonsai (they do make great bonsai as well). If you want a healthy, adult-size ginkgo eventually, you need to put it in a bigger container at this point. I would say a minimum of a one gallon container. Your little tree should also be in full sun. I have all kinds of wild life in my yard as well, and occasionally something gets nibbled at but that's the chance you risk in the great outdoors I guess. How cold does that porch of yours get over the course of the winter. If it goes below freezing on a regular basis, it is too cold. Roots growing in a container are exposed to much colder conditions in the winter than roots growing in the ground. I overwintered a containerized ginkgo for several years in an attached garage that never went below freezing but was cold even to bring dormancy (between 40-55 F. for coldest part of winter). I hardly watered my plant over the course of the winter under these conditions (maybe once a month) during mild spells. Also, you might start apply a very mild fertilizer while it is in active growth. Hope this was helpful. Good luck!

trees aren't meant to grow indoors ... they need dormancy .... i have three ginkos near ann arbor/adrian ... they do just fine in my z5 MI ... your garage .,... with the door closed.. is at least z6 or 7 .. and a good place the 'harden them off'.... rather than jsut throwing them outside ... .. put them out there for the next week ... watch them go dormant.. and then plant them in the ground and let mother earth care for them for winter ... mulch well .... the further you get in your machinations.... from mother earth ... the higher your chances of losses ... its really hard to fool mother nature.. so instead of trying to beat her.. let your trees join her .... ken

You could keep it in the same container if you lifted it and added more potting mix. All plants growing in a soilless peat, coir, or bark based medium will require fertilization at some point. You may want to consider deciding what kind of medium to grow your bonsai in so that you can switch it over soon. Two of my favorite specimens were ginkgo grafts....very enjoyable and rewarding to work with.