Tree Tips

December 2021

This year has been a transitional year for us all. We’ve gone from total isolation to in-person meetings as the vaccinations have increased and the restrictions at the church have relaxed a bit. They have allowed us to get together for our potluck Christmas dinner and year-end auction. Whether it’s a main course, side dish or family favorite, let’s all share the spirit of the holidays together. We haven’t been able to meet with our friends and practice our bonsai skills together until just recently. Remember to bring in bonsai related items — trees, books, tools, pots, etc. — as well as your checkbook for the auction and next years dues. It’s always fun and you might score some neat stuff.  

We are indeed fortunate that Juan Cruz instituted the Zoom meeting format both last year and this year, and arranged for some really great bonsai professionals to give us programs that expanded our bonsai horizons.

Going Into Winter

The nights are going to be cold (mid 30’s) and ideal to set good flower buds on fruiting trees. 

We had decent storms in November to start off the rainy season (for once). I hope we get some storms this month. Check trees for water needs. Some aren’t using much water and others are really thirsty. 

Move and rotate your trees so those trees needing more water are together. All shade cloth can be put away until spring. 

Tropicals and sensitive trees are vulnerable to cold snaps and the most likely time is now through the end of January. Bring them into a garage or a sheltered area near heat or put a incandescent light bulb (if you can find one) near them to give them some warmth at night. 

Conifers

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 broad leaf 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 sun to penetrate into the lower branch interior. 

Broad leaf 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 to strengthen interior branches, thus preventing them from weakening and eventually dying. Weak branches should not be totally stripped of interior foliage so that they can gain strength with the heavier load. We will cut back to this interior area from now until early February to create back budding. Start from the top so that you create a pyramid shape where no upper branch is shading the tips of the next lower branch. 

Hardened pine needles can be thinned out without harm to the tree. Multiple buds from this summer’s candle pruning should be reduced to two. Remember that you need to stimulate new budding close in to keep the tree healthy, happy and compact. It allows light in and also gives you 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. We candle cut when we have set the branches in place and want to ramify from close-in to the trunk.

Deciduous Trees

Once half your leaves have turned color, strip the remaining leaves off your deciduous trees. We want to work on them as they are going into dormancy, not when they are totally dormant. They tend to bleed when fully dormant. If you cut back when you strip off the leaves, the shoot shouldn’t bleed. If the wound does drip sap excessively you should wait until late winter to cut back when you transplant. The next month will see almost all of the leaves down from your surrounding landscape trees as well. Get them off your bonsai. You don’t need or want hiding places for over-wintering bugs and slugs.  It is always a mess this time of year and I have to clean them 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 Advice

Rotate your trees. Give all sides access to the sun. The sun is very low on the horizon and will give you one-sided growth if you don’t turn the trees. Careful watering is important especially for evergreens because the foliage mass acts as an umbrella just like in large trees in nature and sheds the water out to the drip line. In our case the drip line is outside the perimeter of the pot. So make sure you check your plants water needs regularly. Put a block of wood under one side of your pot to help drain excess water. Alternate the block from side to side every other week.

If you haven’t done it yet, put super phosphate on the soil. But don’t forget that some nitrogen is needed to enable the other components to work. Some fish emulsion or cottonseed meal should be enough.  Pay attention to any trees that have young growth pushing or are semi-tropical varieties. Again, the freezing cold weather may cause some damage, so protect them.  

Dormant spray — start it now (Thanksgiving and Christmas and Valentine’s Day). I like to spray the foliage and trunks with Ultra Fine® oil or a fixed copper spray like Microcop® or Bordeaux® dormant spray for peach leaf curl prone plants like stone fruits, and pomegranate as well as on other deciduous trees. A few years ago, Barry Coate thought very highly of using the oils as a preventive measure. 

Be sure to wash off oil after an hour on conifers so they don’t burn. 

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 and you won’t have as many problems later.

Mix your soils and clean your pots for transplant season. Gear up for transplant season right after New Years Day.  

Stay safe and enjoy the holidays as best you can. Next year will be better…