Yamadori . . .
. . .translated from Japanese means “. . . collecting plants in the mountains. . .” and is without doubt the highlight of collecting and creating Bonsai. Because of so many difficulties and efforts in doing so, just very few bonsai enthusiasts are practicing this digging on the mountainside.
Basically the collecting of trees in nature is forbidden without the permission of the landowner or the local forestry office. Protected areas are taboo for every kind of digging.
A responsible way of acting in nature is provided when you are collecting in the mountains; for example, no tree should be pulled out when you are having a walk in the middle of summer’s heat, because the rate of death will be 100%. Besides that, one should have the necessary horticultural experience, or in spite of all enthusiasm for the mountain trees, one becomes a treekiller inevitably! For the trees, the loss of leaves and root mass, the climatic switch and the great changes in reference to soil, rain, humidity, temperature etc. . . are often the reasons that they don’t survive the procedure of the collecting.
Although these tortured trees are small and bent, they are important for things like protection against avalanches and erosion, for the covering, nesting and feeding of animals etc. You should remember all of these points before you go into the mountains to collect.
The best time for digging is the first weeks in spring; from April to June, according to the snow on the mountains, especially for larches (Larix sp.), spruces (Picea sp.), junipers (Juniperus sp.), and pines (Pinus sp.). In September and October, mountain pines (Pinus mugo) can still be dug up easily and successfully, because these pines stop their growth at the end of August and in autumn there will be some growth at the roots. Deciduous trees generally should be dug up in Spring (before the buds are swelling).
The best places to find trees suitable for bonsai are in the mountains at heights around 1300 to 2200m, the areas around the timberline are pretty good, a harsh zone, where most bizarre trees can be found. Trees which can be found in areas with falling rocks, steep faces and hollows have usually a more dense rootball than trees on more nutritious soils around the mountain pastures, which have a widespread root system.
Before you start digging, you have to reduce the foliage to a necessary level, but ATTENTION: especially for pines, but also for other evergreen conifers, the reduction shouldn’t be too great. It can die because of the big reduction of the food generating surface (foliage). Larches and deciduous trees can be cut back harder without problems. You have to find a balance of the ratio between the foliage (chlorophyll) and the roots.
Before you start digging you have to take away the loose packed soil and rocks around the tree. I use secateurs, a small saw, a small crowbar and of course my own hands for the job. In the mountains you are almost out of place with a shovel or a spade.
The best success in getting the trees growing on will be if they grow in hollows or directly on big stones or rocks. Actually, you don’t have to dig these plants up, you only have to lift them up (maybe some roots have to be cut). These species show a very dense rootball and sometimes you can put them directly into a bonsai pot, so they can be styled after just one growing season.
It is very important, that you put the uncovered rootball immediately in damp moss if available or in damp cloth or pieces of fabric, which you have to take with you, to save it against drying out. The damp cloths around the roots will then be fixed with special cloths out of burlap, available in nurseries. Some plastic bags can be taken as well.
At home, the tree has to be potted immediately in a wooden box (with enough draining holes), a suitable plastic container or a big bonsai pot. The soil I use is a well draining mixture out of akadama, granite and lime gravel. But everybody has to look to his own experience with soil for yamadori. . .
It is important to fix the tree in the pot with a supporting staff, some wire etc, so the new fine roots won’t be damaged later because of any movement.
In no case should the rootball be cut back at this time to fit in a pot. If necessary you have to use a bigger box right after the removing. But ATTENTION: When the box is too big, it isn’t good either, because the soil might get too wet and that may cause root rot.
In first case, the freshly removed tree should survive. The rootball can wait for 1 to 3 years until the plant has recovered and is strong and healthy enough to be reduced again. After the potting you can put the container in a tub of water, so that the rootball and the soil get stuck together without pockets of air, for better drainage.
The biggest problem for yamadori collected in the Spring is the change in the climate. While in the mountains the last snow melts away at the end of May – beginning of June, the temperature is around 0°C. Because of that, the trees can be dug up only very late, while in the valley, there are already summery temperatures of around 25 to 30 °C. In autumn, usually this problem does not exist. The tree can start growing after its winter dormancy like usual (without stress) and is saved from such an enormous change of temperature.
Initially one should place the yamadori in half-shade and sheltered from wind. Freshly dug up trees don’t need too much water and some air in the soil is good for the growth of fine roots. Additionally, I sprinkle my yamadori every day with a fine mist of water. If the tree survives and starts growing the following year, it can be put into the full sun.
If one has achieves this until now, there should be no styling done on that tree for at least 1 or 2 years or more. It makes sense to style the tree when it is perfectly healthy and has had some periods of growing well (in the valley).
When the work finally starts, one should either style the tree or repot it to a bonsai pot. Both at the same time means too much stress to the tree and that should be avoided.