Now is a good time to be repotting your bonsai. Repotting, styling, wiring, trimming etc. can all be accomplished from now until mid March ish, depending on the weather. Check for bugs, funguses, and any other nasty things that might have climbed onto your bonsai during the fall. We are still having a very dry winter so make sure your bonsai are watered so that they don’t dry out. The strong winds that occasionally blow up the canyons dry out our trees really fast.
Make sure all of your tools are clean and sharp. Prepare all your needed transplanting/repotting supplies prior to beginning. We find that we make a lot more efficient progress when we plan a day or two ahead of time, get the bonsai or stock material all lined up and then go to work on them and spend at least a full day. Applying the force required to do this work is best done in a steady and consistent way. Use Superthrive, B-1, or some other rooting stimulant product. Do not fertilize the repotted bonsai until they have begun active growth again; this should be sometime in April/May.
For gathered material from the mountains you can put a little bit of Horminex 1, 2, or 3 into the pot and water as you normally would. In the middle of April treat all gathered material with Merit or some other ‘systemic’ fungicide, bug killer, fertilizer mix. Most of the pines and many junipers that we gather in the mountains have borers living in them and the use of the systemic product will kill them after 3-5 applications before they begin the move around in your garden.