To talk about autumn care for bonsai, and the first question to ask is, just when does autumn start? The calendar tells us one thing but the bonsai can be saying something else. Deciduous trees make it pretty clear: the leaves change color and start to drop, but the vine maples do this at the end of August, the larches in late September, and the Tridents may hold on until December. Lots of other plants just stop growing sometime between late August and late November. Since there are several autumn chores to do, we can let the trees tell us the appropriate times before protecting our collections for the winter.

Although many bonsai people wait until the end of winter to do their wiring, I like to get that started shortly after the deciduous trees drop their leaves. Branches may be brittle, but allowing the soil to become slightly dry will make them more flexible. If I wait until late winter to wire, I never seem to get all the repotting done in time, and besides, emerging buds are damaged or broken off too easily at that stage.

Two weeks after leaves drop is the time to work on mature Japanese black pines, Pinus thunbergii. "Mature" means that the branches and trunk are already as long and tall as you want and the secondary branches are already developed. (For trees still in development go to the PSBA website and check out the "Care of Pines" article available there.) On the mature trees, remove all two-and one-year old needles. Then thin the current year needles around the bud tips. Leave only four or five pairs of needles around buds in the top 1/3 of the tree, six or seven pairs around buds at the tips of branches in the middle 1/3, and eight to ten pairs around buds in the interior of the tree and on the branch tips on the lowest 1/3 of the tree. Then the pine is ready to be completely wired out and shaped. Pines store a lot of the food in the needles, so the removal of old needles is a good start on slowing their growth in the spring. Since the other two-needle pines mostly do not grow as vigorously as thunbergii, it is better not to remove their needles as aggressively, but rather to leave several more needle pairs at each branch tip. Also you could wait until late winter to remove needles and to wire those other varieties.

Dave DeGroot explained the methods used on beech (Fagus) tree bonsai to increase ramification and dwarf leaves. This same technique works well for hombeams (Carpinus). In middle to late October, snip off the leaves at the petioles to expose the branch structure. Then wherever a branch is leggy and lacking ramification, cut it back leaving only a single plump, strong bud near the tip. Seal all but the smallest cuts with putty or kiyonal.

Wiring and bending the branches then seems to stimulate dormant buds to develop when the tree begins to leaf out. Just as the buds begin to show a little green tip in the spring and then begin to push out slightly, grasp the base of the bud firmly with one hand and with the fingertips of the other hand grasp the green tip and snap it out of the bud. There will be two or more leaves left inside the bud, which will extend within a few days. After that, snip off all but one or two leaves as soon as they have unfolded. With good sun exposure during the growing season more leaf buds will emerge and open inside on the branches.

Azaleas also need leaf stripping in early November. All of the leaves should be trimmed off every branch except the last little rosette of leaves surrounding the developing flower buds. Places where the bonsai divides into multiple branchlets should be reduced to two divisions or even just one branchlet located near the base of the tree. Long, leggy branches can be cut back to any place where a pair of secondaries has emerged. Seal all cuts with putty or kiyonal unless they are smaller than 1/16". Allow the tree to go for a couple of days without water, until the soil surface feels dry and about 1/2" down it is still slightly damp. The tree is now ready for wiring. Branches can be bent with less breakage if they are twisted along their axis at the same time they are being bent. Be aware of which way you are going to twist the branch so you can spiral the wire correctly: that is, so the wire tightens rather than loosens as you twist the branch. Bending the branches seems to stimulate lots of new inside, dormant buds to develop in late-March. A feeding of Alaska Fish in mid-February will enhance this effect nicely.

Finally, as I start to put my trees down on the ground for winter, I put the ones, which do not need repotting, away first. I try to match the trees that need repotting to their new pots and put them away in the more accessible places. I know when February gets here, and it is raining saws and hammers with a 25mph wind blowing, it will be easier getting to the repotting if I have done that much ahead of time. Technically, almost any tree could be repotted any time through the winter and into early spring, if the after-care is good. Newly repotted trees must be protected from any hard-freezes, (about 28 or 29F) for the rest of the winter. And they must be kept slightly damp but not soggy. Most Puget Sound winters either have one or more freezing spells or else a lot of heavy rains, or maybe both. That is why I prefer not to repot my trees until the middle of February or later, when a hard freeze is more unlikely.