Bonsai Tips During Climate Changes

Time is charging toward cold, cold weather! Lets be good girl scouts and boy scouts and be prepared!

We displayed our Bonsai and Bonsai supplies at the Wisconsin and Minnesota State Fairs for over 10 years. During that time we constantly asked our patrons how they over wintered their hardy and temperate climate Bonsai. We are not talking about tropical or tender varieties here. I will detail that in a moment.

From the hundreds of persons we quizzed about this the following is a summary of their achievements and failures.

1. Over wintering outside was usually a failure. This is where you dig a hole in the ground and bury your Bonsai for the winter. Here are the negative elements:

A. The pots quite often broke, thus losing your Bonsai to drying of the now exposed roots because there was no moisture and sometimes no soil inside the broken pot. Even if the pot didn’t break completely apart the Bonsai could be drastically weakened from this.

B. Varmints, meaning gophers, rats, mice ate the roots and top growth.

C. Even though the Bonsai was covered with snow it dried out during this time. This can happen because the roots are frozen to such an extent that they just dry out. This can also happen because the soil thaws and freezes resulting in heaving of the soil and the roots to such an extent that both the soil and the Bonsai’s roots dry out. There is quite often damage to the branches and for an evergreen a tremendous amount of leaf damage.

D. There are temperature points at which certain Bonsai or parts of the Bonsai will die. As for example when the root temperature of Japanese maples goes below 16 degrees F the roots will die. We have had this happen to us in the nursery when we had very low temperatures on our Hinoki cypress (Chamaecyparis obtusa nana). These were 10 year old specimens on 3 foot tall nursery tables located outside. We had one of our rare 12 degree days. There was no obvious harm shown at that time. But, when the temperatures started rising the Bonsai started turning black. We lost over 100 of them to old man winter and his fickle cold. The roots died and the Bonsai was not able to recover from that loss of sustenance provided by its root system.

2. Construct a cold frame. There are many books available that will give you a “how to” to do this. This appears to be acceptable except that varmints, not watering or giving some ventilation during warmer spells can cause a problem. You just can’t forget your Bonsai and think they are not around.

3. Over wintering in a cold room, cool room, garage, unheated room or basement. This seems to be the best of the alternatives. A number of hobbyist stated that they were successful in keeping their Bonsai where the temperatures were just above freezing with some light, even artificial light. You still need to water. How often will depend on many factors (temperature, humidity, soil porosity, growth of the Bonsai, even the time of the year). So you need to develop your own routine on this. Check this routine periodically as you will need to increase or decrease the timing of your watering.

How we do it in our part of the world – Dallas, Texas, which is zone 8 or 9 depending on which map you read.

We have Japanese Black Pines, Japanese Shimpaku and Japanese Maples.

1. We dig about a 4 inch deep hole in our flower beds which face South large enough to accommodate one of our Japanese black humidity trays. We then place the tray upside down in the dug out area and then place the Bonsai on the tray. We do this so the bonsai will not grow roots into the underlying soil. It will send out some roots between the pot and the tray, but that growth will be minimum. If we don’t have some form of barrier we can have a foot of roots outside the pot. This excessive growth can clog up the pot’s drainage holes and cause water problems. Then we cover the Bonsai pot with our triple screened pine bark. As the bark is usually very dry we try to wet it first by putting the bark in a bucket and then filling the bucket with water. After you cover your Bonsai with the bark, you need to water the bark more than normal for a few days to ensure that it is wet enough. This is usually enough protection here in Dallas. We water daily. Now if there will be a really cold temperature say in the 20s or teens we carefully cover the Bonsai with sheets to protect them even further. We then water down the sheets to offer a barricade of ice around the Bonsai. Normally this low temperature lasts only a day or so. So it’s off with the sheets as soon as possible.

2. Japanese maple branches can be damaged by low temperatures so we are extremely careful during these times. Death will occur when the root temperatures are 16 degrees or below. Remember that’s root temperature and not air temperature.

As to your indoor Bonsai you have two items to be concerned with now that the outside temperatures are plummeting.

1. Light – If you have placed your indoor Bonsai on a window sill to afford it Mother Nature’s adequate light you need to be reminded that the natural light is not what it was in June or July. The length of the day and the intensity of the light is greatly diminished. What to do? You many need to add artificial light so that your Bonsai will survive during this time of very low light. These lights are available at your local nurseries and most of the big box hardware stores. Plant lights come in incandescent and fluorescent types. Usually these are used for 16 hours daily and are kept about 12 inches from your Bonsai. Automatic timers are available at affordable prices to make this chore easier.

2. Water. You are now heating your environment. With this heat comes excessive dryness. Your home can be like a desert with 12 % or so humidity. This may cause your Bonsai to suffer from drying of the leaves and soil. Some of this can be ameliorated by using a humidity tray and nachi rocks. Both of these items are available on our website.

Just remember that you can’t neglect your Bonsai. Take good care of them and they will reward you many times over with their serene beauty.

Bonsai Channel Update – Secrets of Bonsai volume I & II Teasers
Last month we placed teasers of the secrets of Bonsai Videos on The Bonsai Channel. ( Head there now and check them out! They are really great videos! ) Well, we are pleased to announce that the videos are finally in stock!

Also, we will be making our update to the Bonsai Channel mid-month, we will send an announcement when it is ready to view.

Thanks for all your advice and kind letters! We appreciate it!

Visit the Bonsai Channel

Reproduced with permission from Dallas Bonsai.

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