Tree Tips

December 2024

Christmas Potluck and Auction

This year, we will be getting together for our Potluck Christmas Dinner and Year-end Auction this Thursday, December 4th. Whether you're bringing a main course, side dish, or family favorite, let’s all share the spirit of the holidays together. I’m bringing a spicy lima bean casserole—a family favorite.

Remember to bring Bonsai-related items: trees, books, tools, pots, etc., as well as your checkbook for the auction and next year's dues ($40 for single, $50 for family). This auction is 100% for the club and covers many expenses we incur throughout the year. So, Ho Ho Ho! Be as generous as you can. It’s always fun, and you might score some neat stuff.

Tree Care Tips for December

By mid-month, the nights will be cold (mid-30s), which is ideal for setting good flower buds on fruiting trees. We had some rain in November, so I hope we get more storms this month. Check trees for water needs—some aren’t using much water, while others are really thirsty. Move and rotate your trees so those needing more water are together.

All shade cloth can be put away until spring. Tropicals and sensitive trees are vulnerable to cold snaps, particularly from now until the end of January. Bring them into a garage or a sheltered area near heat, or use an incandescent light bulb (if you can find one) to provide warmth at night.

Wiring and Styling

Winter is a great time to wire and style your conifers (except bald cypress and dawn redwoods). You can clean out the crotch growth in conifers, deciduous, and broadleaf evergreens unless you need a new branch to replace a weak older one that won’t back-bud.

Also, clean out and trim back excessive foliage in the upper part of the tree to allow sunlight to penetrate into the lower branches. Broadleaf evergreens like oaks, citrus, and olives can have their upper leaves cut in half to allow more sunlight into the interior core of the tree, strengthening interior branches and preventing them from weakening and eventually dying.

Weak branches should not be totally stripped of interior foliage, as they need it to gain strength. We will cut back to this interior area from now until early February to encourage back budding. Start from the top to create a pyramid shape where no upper branch shades the tips of the next lower branch. Hardened pine needles can be thinned out without harming the tree.

Multiple buds from this summer’s candle pruning should be reduced to two. Remember, you need to stimulate new budding close in to keep the tree healthy, happy, and compact. This allows light in and provides room to apply wire. Also, remember that June candle cutting is done on more refined trees to increase ramification, not on trees that need basic branch structure.

Leaf Management

Once half your leaves have turned color, strip the remaining leaves off your deciduous trees. We want to work on them as they enter dormancy, not when they are fully dormant, as they tend to bleed then. If you cut back when stripping off the leaves, the shoot shouldn’t bleed. If the wound does drip sap excessively, wait until late winter to cut back when you transplant.

Also, spray the bleeding wound with cold water, as this sometimes helps stem the flow of sap. The next month will see almost all of the leaves down from your surrounding landscape trees. Get them off your bonsai; you don’t want hiding places for overwintering bugs and slugs. It’s always a mess this time of year, and I have to clean up and get the weeds— which never stop—out of my pots.

Regardless, it’s a good time to study the future of your trees and decide which branches to eliminate and which to keep. Leave a little stub when cutting back at this time of year.

General Maintenance

Rotate your trees to give all sides access to the sun. The sun is very low on the horizon and can cause one-sided growth if you don’t turn the trees. Watering is especially important for evergreens, as the foliage mass acts like an umbrella, shedding water to the drip line, which is outside the perimeter of the pot. So make sure you check your plants' water needs regularly.

To help drain excess water, put a block of wood under one side of your pot and alternate the block from side to side every other week.

If you haven’t done it yet, apply super phosphate to the soil. Don’t forget that some nitrogen is needed for the other components to work. Some fish emulsion or cottonseed meal should be sufficient. Pay attention to any trees that have young growth pushing or are semi-tropical varieties, as freezing temperatures may cause damage. Protect them accordingly.

Dormant Spray

Start your dormant spray now. I like to spray the foliage and trunks with Ultra Fine® oil or a fixed copper spray like Microcop® or Bordeaux® for peach leaf curl-prone plants like stone fruits and pomegranates, as well as on deciduous trees. A few years ago, Barry Coate recommended using oils as a preventive measure.

Be sure to wash off the oil after an hour on conifers to prevent burning. Separately, you can use lime sulfur, except on Ume (flowering apricot). I spray three times: at Thanksgiving, New Year, and Valentine’s Day just before bud breaking. (P.S. Lime sulfur will turn your copper wire black but shouldn’t hurt the tree.) Do your spraying now to avoid problems later.

Prepare for Transplant Season

Mix your soils and clean your pots for transplant season. Gear up for transplant season right after New Year’s Day. I will be conducting a transplant program on January 4th, our first meeting of the New Year. See if you can get supplies (soil, tools, pots, wire, etc.) from Drew Tucker in our club or from Jonas Dupuich at Bonsai Tonight, or Peter Tea online. 🌳