More snow

This is the winter holiday (talviloma) week here in Finland and is traditionally the coldest week of the year. In the past few years this has not been the case but this year this has come back with a vengeance. We have had temperatures of minus 17°C for the past few days and more of the same is expected for the coming week. Along with the cold temperatures has come some more snow. We had already quite a lot and are now struggling to find a place to put it all.

At least the more snow helps to cover my Pine trees. I have not completely covered them because they are also positioned close to my house, even though I could easy do so with the amount of snow that we have had.

The deciduous trees are still in my garage on the heater bed. I have had this on a couple of times to relieve the temperature a little, but the good thing is that the garage is keeping the temperature some 8-10°C warmer than the outside temperature. As you can see I have placed some snow on the pots which will slowly melt into the soil to prevent the soil from drying out.

Winter protection

As mentioned in my earlier post the winter can get quite cold in Finland. We have recently experienced temperatures of -25°c only last Saturday. My bonsai (potensai) collection at the moment is quite small so I am able to offer more protection for the deciduous trees by placing them in my garage and on the heater bed I made, but the two pine trees I have left outside.

The pines, as with all evergreen species, require some light during the winter period as photosynthesis still takes place. I moved the pines closer to the house to get some protection from any strong winds, we could get during the winter, and to remove them from the direct sunlight that we can easily get on a nice winter's day. Exposure to direct sunlight during periods of sub-zero temperatures can cause damage.

When the first heavy snow fell I covered the boxes that the trees are planted in with the snow. This helps to keep the temperature under the snow a little higher than the actual outside temperature and protect the trees from any heavy frost. Now we wait patiently for spring to see if all of these various techniques for protecting the trees during the winter period have paid off.

Heater Bed

Winter in Finland can be quite cold with temperatures going down to minus 25-30°c. In the south of Finland where I live the temperature tends not to be so cold but can still easily be more than -15°c. These low temperatures mean that protecting the outdoor bonsai during this period can be a challenge.

I have a garage where I place the deciduous trees that will protect them from the frost and the cold wind, which is one of the main culprits for killing the tree because the wind can dehydrate the tree during this period of dormancy, but this does not protect them from the really cold temperatures. The garage already keeps the temperature a few degrees higher than the outside temperature and in general temperatures down to -10°c are ok but anything more than -10°c it is advisable to provide some extra protection. The garage has electric floor heating installed but this costs a fortune to keep on, as I found out to my horror last year when the electric bill arrived, so this year I thought I would build a small heater bed for the trees to sit on that I can put on when needed without costing a fortune.

The heater bed consists of a wooden frame with a thermal insulation base on top of which are two layers of sand. Sandwiched between the layers of sand is a heater cable attached to a metal grid.

The following photos show the step by step build of the heater bed.

Step 1. Wooden frame
A wooden frame was made as shown in the image below. The size of the frame was approx 120x60cm. The width of the frame matched the width of the thermal insulation material I would use. I attached a large sheet of plastic to the sides and bottom to help to retain the sand from falling through.

Step 2. Thermal insulation material
On top of the sheet of plastic I placed a piece of thermal insulation material. This material is about 4cm thick and very stiff. I could of used some type of board to form a firm base to hold the sand but this is what I had available and I thought it would help in maintaining some of the heat.

Step 3. Heating cable
The heating cable, which can be obtained from a local electrical shop, is specially designed to be used outside and for keeping things warm. Normal use of this cable is to warm water pipes, either the main water coming into a house or attached to drain pipes to prevent the water from freezing during the winter. The temperature output of the cable is approximately 10°c and uses 10 watts per metre. The length of cable I have used is 10m meaning that the power consumption is 100 watts. The cable is attached to a metal grid the size of the area with cable ties. I attached the cable on both sides of the metal grid at equal distances to try to get an even distribution of the heat. The cable is already fitted with a standard electrical plug as seen in the bottom of the image.

Step 4. Sand
The finished cable was taken out of the frame and a layer of sand approximately 2-3cm deep was added on top of the thermal insulation material. I then placed the cable on top of the sand and then proceeded to add more sand to cover the cable. I was not sure how much sand I needed so I started with another 2-3cm. The reason I wasn’t sure how much sand to add on top of cable was because I didn’t know how warm the sand would get when there was power to the cable. I wanted the sand to get warm but not to too warm and even though the temperature output was only 10°c the fact that I had looped the cable close together meant that the combined temperature could be more than that. As it turned out the difference between the ambient temperature and the temperature at the top of the sand was about 10°c. Because I am planning to use this heater bed only when the temperature is really cold the sand will never get above the magic temperature of +10°c, temperature that would start to represent that spring was here, so this difference is fine. If the temperature had been too high I would have simply added more sand to absorb more of the heat. In the image below you can see a thermostat to the left hand side. The thermostat takes the ambient temperature and a sensor, normally used to take the outside temperature, is inserted at the top of the sand to give some indication of the temperature of the sand.

Step 5. Placing the trees
We have been blessed that during November and the beginning of December the temperature had been quite warm for this time of year with temperatures even reaching +8°c on some days. But as can easily be the case here in Finland the winds change direction and we go from +2°c to –12°c overnight. This happen one night a couple of weeks ago and then that was the time to move the trees inside the garage and on to the heater bed. I didn’t actually turn the heater bed on because the garage was protecting the trees from the frost and the ambient temperature was only -6°c. Winter really started to come after this day with daily temperatures of –10°c to –16°c. During one of these days I turned on the heater bed as the temperature inside the garage was now –9°c. The out come was that the sand warmed to a nice temperature of +2°c. Perfect to keep the toes (roots) warm of my small collection of bonsai (potensai).

Cat litter as inorganic soil alternative

I mentioned earlier about my own bonsai soil mix. This isn’t as scientific as it first sounds. As many of you may already know bonsai enthusiasts throughout the world have been turning to cat litter (kissanhiekka) as an inorganic soil alternative to Akadama. Akadama is expensive and can be difficult to obtain here in Finland, often only available by mail order from another country. Cat litter is of course much cheaper and can be purchased from any supermarket. I have tested a couple of brands to establish if it retains its shape when wet and frozen and found that the brand ‘Rainbow Kevyt Kissanhiekka’ is the best cat litter that I have come across at the moment. I have used this cat litter for over a year for all my bonsai, indoor and outdoor, without any problems. The soil mix can be 100% cat litter if you require, but you can also mix it with other ingredients for specific tree types or to suit your own personal preferences. For example you can add some grit for a drier mix used on pines, junipers etc. or some pine bark to retain more water.

When using any material for bonsai soils it is important to remove the small particles and this is also the case with the cat litter. I have found with the brand that I am using that the largest particles are ok and remain in my mix but I sieve out the smaller particles less than 2mm. These small particles are not needed in the mix, as they will not allow the water to run through as easy.

My own bonsai soil mix has been made up of roughly 50% cat litter and 50% pine bark. The pine bark is also purchased from any local garden centre and then I run this through an old food processor to cut into smaller pieces. Again, as with the cat litter, I sieve out the smaller pieces and this time also remove the larger pieces that are bigger than 5-6mm. This bonsai soil mix I have used especially on my indoor bonsai because it helps to extend the time between watering that can be problem if using 100% cat litter.

Two of the most important tasks that need to be performed correctly for your bonsai to grow, watering and feeding, have been made easier by using cat litter.

Watering

Watering of my bonsai was a job that was a little difficult to understand in the beginning with questions like How often should I water? and What different watering schedules are needed for different trees? All this is now history when using cat litter. If required I could water my bonsai everyday, this can easy be the case in the summer, without any problems because any excess water not retained by the cat litter simply runs out the holes in the bottom of the pot or container.

Feeding

The use of cat litter has also changed how I feed my bonsai. As with the watering I was constantly reading about different feeding systems for different types of trees, but now I feed during the growing season every 10-14 days with a balanced feed knowing that the daily watering regime during this period will wash away any excess fertilizer before the next dose.

Conclusion

Cat litter is a cheap, easily obtainable alternative bonsai soil that will help to keep your bonsai growing vigorously with regular watering and feeding regimes.

Yamadora collecting

There isn't many jobs that can be done this time of year, especially when your collection of bonsai is as small as mine is at the moment. The indoor bonsai need normal attention, watering, light trimming etc., but the outdoor bonsai are already starting to prepare for the winter. Protecting them from the cold, especially the cold wind, will be my priority during the next month to 6 weeks. After this more protection is needed for the outdoor bonsai but I will return to this matter nearer the time to show how I prepare my trees for the cold temperatures that we get here in Finland.

What this time does give me is the possibility to search and identify potential bonsai (potensai) in the form of yamadora that can be collected in the spring. One source of bonsai material that I have noticed is simply sitting next to many roads and tracks. Here in Finland there is a trench / ditch along the side of the road for the rain water to run into and for the snow to be pushed into during the winter months.

Trees grow in these trenches which are cut each year by the verge cutters that come along to cut the grass and weeds. The continual cutting of the tops of the trees produces thick trunks that is the heart of any bonsai.

Any type of common tree in our area can be found growing in the trenches as shown in the photos. The most common tree in the photo was Aspen (Populus Tremula) but there was also a Scots pine.

I know that Aspen is not a common tree for bonsai material, but if nothing else it will allow me to continually improve on my bonsai skills. Now we wait for the spring to see how some of these trees look when removed from the ground.

Japanese maple #1

The cold nights are starting to come now in this part of the world. These nights start to turn the leaves on the trees all different colours. We have some big maple trees in our garden and the tops of these turned almost bright red. Maples are of course very good at showing off their colours and Japanese maples in particular display such wonderful colours at this time of year.

This is the same tree I purchased from Bauhaus that will need an immediate repot next spring, but you can already see that in a few years once the canopy has developed further this should be a nice tree.

Scots pine #2

This Scots pine (Pinus Sylvestris) was collected a couple of weeks after the first Scots pine.

This was located on the side of a rock and again the roots were all on the surface of the rock, making it easier to collect. Bringing along as many roots as possible, not forgetting the Mycorrhizal fungi, helps to make the survival rate of pine trees higher.

The photos below show the sort of location that these potensai can be found. Places exposed to the weather where the wind can blow strongly and the tree is attached by only a little soil are ideal conditions for nature to make the sort of tree bonsai enthusiasts are interest in.