by George Buehler

Now is the time to start thinking about what needs to be done in the next couple of months. It seems to be early to think about putting away our trees, but the high temperatures keep getting lower and lower every day. So let's begin a list of what we should be doing.

Pictures

Most of you who read this missal regularly know that I preach taking pictures of your trees. At this time of year, when pictures are taken, not only are we recording the overall appearance of the tree, but we are also recording the results of our summer work and showing what needs to be done to the tree in the next wiring or trimming job.

For the deciduous trees, especially those that exhibit a lot of color in the fall, this is also the time to record that. When the weather really turns cold and we can't get out, these pictures can be put into a slide show to simply sit and enjoy the color. Another possibility would be to use one of these pictures as either a screen saver or as your wallpaper.

If you can, move the tree off the stand and place it against a suitable backdrop. The pictures do not need to be of professional quality but should be detailed enough to show the overall shape and if possible, some branch structuring. I always try (and I say try because it always doesn't happen) to get the four views. I also try to get one shot of the front with the pot. This is done so that I can use Photoshop to change the pot without actually changing the pot. [Perhaps someday I can put together an article on how to do that].

Timing

Tropicals – When the weather starts approaching overnight lows of about 55 degrees, it's time to start the fall bonsai shuffle. When the weather people say the temperature will be 55 degrees, place the tropicals inside overnight (I sit mine in a plastic tray on the kitchen floor). The next morning, as the sun comes up, take the tropicals back outside for the day – as long as the daytime high is predicted to be above 55 degrees.

If the daytime highs are not predicted to reach 55, the tropicals can be left in their temporary position, or they can be placed in their permanent winter position.

Deciduous – This group need to be exposed to frost before they are put away. This group will 'tell' you when they are ready to be put away. Just like their big brothers in the landscape, these little trees’ leaves will change color, start to dry up, and fall. When most or all of the leaves have fallen, then move these to their winter quarters.

Bear in mind that for some trees, the leaves don't all fall off until the new growth in spring pushes them off. For these, you will have to decide when to put them away. Typically, when about 75% of the leaves have started to dry up (or have fallen off), I move them to their permanent spot for the winter.

Evergreens – My evergreens are the last to leave the display area. Typically I wait until the daytime temperatures are struggling to get above freezing before they are put away. The chamaecyparis and boxwoods go first followed by the rest.

Where to Overwinter Them

There are several ways to overwinter trees.

Tropicals – Of course, tropicals have to be protected from the cold, so a nice warm place needs to be found. For those who have a heated greenhouse, a better place cannot be found. However, most of us don’t have this luxury, so we have to find other places. Many people put their tropicals in a window. There are several problems with this method. The first is that during the day, any window treatment has to be opened to give the tree light. This can allow cold air to enter the room which drives up our heating cost. Additionally, the tree should be supplemented with additional lighting for those cloudy and short days. Another problem is that floors, furniture, etc. have to be protected from any water that can accidentally be dropped on them. If this is the only option, then the bonsai artist has to live with it.

A better option is to build or buy a table to put into the basement or spare room and equip the table with adequate lighting. The lighting can be fluorescent or a high intensity lighting system. If a fluorescent system is used, approximately one two-tube 4 foot fixture should be used for two plants (depending on size). If the trees are large, additional fixtures will be needed and perhaps some reflective material to light the lower part of the tree. The lights should be set on a timer that allows the light to be on about 16 hours per day.

Conifers – Junipers, pine – For these evergreens, I recommend (and practice) putting them in a protected area outside and mulching them in, using pine straw or cypress mulch. Make sure that the area chosen is protected from the winds and the trees are not placed under the eaves of the house (where they wouldn't get any rain/snow during the winter and would have to be periodically checked to see if they need watering). Protection from the wind is especially important to the new branches that were developed during the growing season. When placing the trees, also make sure that the branches aren’t bent.

When I place the pots in the area where they will spend the winter, I partially bury bricks in the ground to sit the pots on. Then I spread some of the protective mulch between the bricks. Finally I place the pots on the bricks and cover the pots with mulch up to the first branch. This is done to allow water to drain from the pots. The reason I go to this trouble is because one year I placed a very nice shohin white pine in the protected, area but it was placed directly on the ground. When I took it out the following spring, I found that the pot had sunk into the soil and had been water-logged thoughout the winter. Of course, the tree subsequently died that growing season from being water-logged.

Before I put the trees in this area, I take a sheet of newspaper and cover the soil with it. I then mist the paper to ensure that it sticks. This is done to make clean-up next spring easier. I am always surprised at how many fine mulch particles are deposited onto the soil, if not protected. It is hard to get these particles out of the soil.

Evergreens – Chamaecyparis, boxwoods – I like to put them in an unheated garage. Of course, this means that they will have to periodically be watered during the winter, but I think this is better than risking getting “winter burn” on them. I know many people put these in the same areas as the conifers and suffer no problems. If the area can be protected from the winds, it probably would be OK. I just don’t want to risk it. Watering has to be carefully controlled. Since the plant is dormant, it doesn’t need ‘normal’ amounts of water. It just needs to be moist. Deciduous – These can also be buried in a mulch bed, but here again I like to put them in an unheated garage. The reason is that I can start working on them earlier than if I had to go out, uncover them, bring them in, then re-bury them and be dependent on how wet or frozen to the ground they are. The area of my garage where the trees are stored is relatively dark, thus preventing, or at least slowing down, any new growth on the warmer winter days.

We need to discuss placement of the trees in the unheated garage and the types of unheated garages. Garages can be attached or unattached to the house. Attached garages can, and probably do, receive heat from the house. Unattached garages, not receiving heat from the house, suffers from the potential of getting too cold. Therefore placement of trees is extremely important in either structure. For attached garages, the trees should be placed as far away from the heated house wall as possible. For the unattached garage, the trees should be placed on the side away from the coldest wind source or on a non-south wall. It is not important that either structure has a light source. Actually, it is somewhat better if there isn’t any light, or at least a low light source. My garage, where I store my trees, is an attached garage, with the heated wall on the southeast side. The trees are placed on the northeast side, on the floor, and on shelves. There is a window on this side and some trees have to be placed in front of this window due to the space available. I have placed elms, maples, and several fruit types in front of the window, and I can’t tell much difference from having the same types on the floor under some shelves – essentially in the dark. Therefore, in my situation, I don’t pay too much attention to what is placed in front of the window.

Rather than putting trees in a garage, a cold frame can also be used. Basically, a cold frame is a large hole in the ground with a covered top where the trees can be stored for the winter. The walls of the hole are made of concrete blocks, bricks, or wood. Most people insulate the sides to help keep the cold in. The tops used to cover the cold frame can be glass, clear plastic or even plywood. Remember that the dormant tree doesn’t need light to survive. If a clear top is used, care has to be taken since during warm temperatures and a bright sunny day, the inside of the frame can easily reach high temperatures. If this occurs, the top of the frame will have to be opened to keep the inside cool.

Pot Cleaning

No matter where trees are stored for the winter, before they are put away, the pots should be inspected. Look under the pot to make sure the drain holes are open and no roots – or worse – critters are clogging them. If there are roots 'peeking' through, cut them out. If there is still wire holding the tree in the pot, this is probably a good time to remove it [but check the stability of the tree before these wires are cut].

I try to remove the moss from the top of the pot before I put it away. This allows water to pass through the soil more easily and to obtain uniform watering. If there is any moss on the trunk, make sure it is also removed, especially on the cork bark type trees. When the moss is removed, put it someplace outside where it can grow for next year’s shows.

Check each tree to ensure that there are no styling wires left (unintentionally) on the tree. If there are, remove them or else you might end up with wiring scars when the tree starts its flush of growth in the spring.

Insecticides/Fungicides

If the trees suffered from insect problems during the growing season, consider treating the tree. A good idea is to wash the tree down with a strong hose spray before you bring it in to insure that any stray bug is washed off (of course, scale will not be removed with this method). A dormant oil spray or Neem oil is a good choice at this time of year on the deciduous trees prior to bringing them in. On tropicals, make sure that there is no scale on them before you put them indoors. If the trees had scale during the growing season, treat them carefully and thoroughly before they are brought into the house or greenhouse. If chemicals are used, the tree should be sprayed several days in advance before moving indoors so that some of the chemicals can dissipate. Another alternative is to use one of the systemic powders on the soil surface. If you plan on using one of these powders, it should be applied several weeks before it is brought in to allow the tree to take up some of the insecticide.

Although I like to use chemicals carefully and for specific purposes, adding a fungicide to the trees that are either brought in or placed in a garage is probably a good idea. The soil will generally stay slightly wetter in the protected environment, leading to a possibility of several fungus problems. Even if there is no problem, addition of the fungicide will not hurt the tree.

Fertilization

Should trees that are dormant be fertilized and, more importantly if you do, will the tree use it? In looking through my bonsai library, all that have information about fertilizing state not to fertilize in the dormancy period. I think that if an evergreen is fertilized with the normal amount of fertilizer, it could potentially start growth when we have those warm winter days. For deciduous trees, it probably doesn’t do too much damage; but, if there is fertilizer present and the tree starts some growth during a warm weather period in the winter, the fertilizer will be taken up and may start plant growth. If any fertilizer is used, it should be a low concentration, low nitrogen (or no nitrogen) fertilizer. I would recommend that the trees not be fertilized during the dormancy period.

Tropicals are treated differently. During the time the trees are under lights, I try to fertilize them with a dilute (about 50% of normal) concentration of a balanced fertilizer every second or third time I water. Make sure that the tree is watered before the fertilizer is added to prevent any root burn.

Bench Cleaning

Once all the trees are removed from the growing benches, it is time to clean, inspect and repair them. A Lysol solution is used to scrub the benches/stands to remove the summer dirt and grime. Use a scrub brush to work the surfaces and get between the boards. If there is any soil between the boards, now is a good time to clear it away. Don’t forget to wash under the table too. Use a hose to wash off any residual cleaner.

Inspect the benches/stands for any loose boards or boards that need to be replaced. Although this is not the best time to be working on stands due to the cold, it is a great time to get this maintenance task done. It will also allow for a quicker start come spring.

Notes

Most of you know that I couldn’t finish this article without a word (or two) about taking notes. As I put my trees to bed for the winter, I examine each one to make any notes on what needs to be done come spring. Does it need transplanting, wiring changes, restyling? I have had several instances where I examined a tree and in comparing pictures from previous years or even the previous growing season, I came to the conclusion that the tree was not planted correctly and needed to be turned slightly or planted at a different angle. This is also the time to decide if a new pot is in order. After all the trees are put to sleep, this is a good time to get your notes into an electronic or more readable form