January Zone 7/8

If you missed root-pruning and transplanting your Chinese Quince (October - December), you can do so this month if normal bud activity begins. 

Apple, Crape Myrtle, Maples, Pines - black and white, Japanese Quince - after flowering, Spruce, Sweetgum.
Cedar, Chamaecyparis - Hinoki, Cryptomeria, Fir, Pines - all, Podacarpus, Spruce, Yew. 

Citrus in a greenhouse environment.
This month you need to prepare for the activities in forthcoming months. A large calendar with spaces each day of the month is excellent. Place it where you can see it easily as a reminder of bonsai things to do. List the things to do on the calendar and then follow through. By using a calendar, you can pace yourself to do all the necessary preliminary tasks and you won't be overburdened during the very busy months of March, April and May. 
If you haven't applied a dormant spray in late fall, do so now. You can use either refined oil or lime sulfur on you evergreens and deciduous plants. Refined oil is recommended for broad-leafed evergreens and conifers (pines, juniper, cedar) and is easier to use. Follow directions on the label and do not exceed recommended formula. This is an excellent control for over-wintering pests and fungi. 
Wash all containers that were used in training and growing bonsai. Use a mild laundry detergent, rinse thoroughly with clean water, and then soak for 10 minutes in a household bleach (not scented) solution of 1 part bleach to 9 parts of water. This is a strong solution, so do use plastic gloves or a pair of tongs when placing containers into the bleach solution and removing them from the solution. This soaking sanitizes the container and will kill any fungi which may have contaminated the container. 
Prepare soil mixes for your potting and re-potting in the next few months. On nice, warm days, you can re-shape your deciduous trees with light pruning.If you have wired any bonsai in the late fall, you should check to make certain the wires are not too tight. Even though trees are dormant, there is a certain amount of  
growth that takes place. Remove the wires if you see signs of wire damage to the bark. 
Mid-January is an excellent time to graft fruiting trees and pines. This is a good method of propagating plant material that does not readily strike roots from cuttings or air layering. Seal the grafts and give protection from freezing during the remainder of the winter. Collect moss and store it in a suitable location (cool shady area) in your garden for use in later months for potting and re-potting. 
Photograph trees in winter silhouette for later training. It is much easier to see the structure of deciduous trees without foliate. Use the  
photographs for re-shaping or changing your design during the growing season. 
Plan collecting trips to middle and south Georgia in February. Collect native trees in North Georgia during March. Cold winter winds can cause soil in containers to dry out very quickly. Be certain to water your trees after several windy days without any rain. To be certain, check the soil in containers at least once each week.