How to Grow Your Own Bonsai Tree
Five Ways to Raise Your Plants for Bonsai
- Plants Collected From the Wild
In addition to these methods of obtaining a bonsai, some firms are now supplying bonsai that have already had their initial training, and sometimes they are planted in suitable containers. These ready-made bonsai may or may not be entirely to a buyer’s liking; if they are not they can, to a certain extent, be altered and improved by the new owner by well-thought-out training and pruning. If the tree has not been planted in a way that pleases, this can also be adjusted when it is repotted.
Grafting and layering are also used in nurseries, but on the whole, amateur bonsai growers would be well advised to content themselves with other methods.
Each method is quite simple and may have advantages over the others, depending on the species concerned and whether or not large numbers are required.
1. Growing Bonsai From Seed
One of the chief advantages of raising plants from seed is that large numbers can be obtained relatively cheaply. It is an interesting and rewarding method, especially if the seed has been collected by oneself. Seeds of conifers, beech, birch, Chaenomeles, and many others can be collected quite simply, and there are seed firms that supply seeds of a very wide range of species.
It should be remembered that the resulting seedlings often show variations and some may have to be discarded, but sometimes one may be fortunate enough to find a seedling that gives evidence of superior quality. Variations which can be detected at this early stage are usually shown in leaf shape and color. Thus, any seedlings with more attractive leaves should be kept, whereas weak and unhealthy seedlings must be discarded.
Very hard-coated seeds, those of cherry, quince, Chaenomeles, beech, Cotoneaster, and other Rosaceae species, yew, ginkgo, Illex and limes, germinate slowly and benefit from a process known as stratification. After collection or delivery, the seeds are placed in layers in pots or boxes of sand, which are covered with wire netting to keep birds and mice away, and put on a well-drained surface—ashes or clinkers—on the north side of the wall or hedge. Care should be taken to label the pots as it is easy to forget during the following months which seed was put in each pot. (See The stratification of hard-coated seeds in a 5-in. pot diagram.)
They should be left for 12 to 18 months, and the more they are frozen, the better; frost seems to help germination. Before sowing, usually in the spring, the seed may be sieved or washed free of sand and then sown in the orthodox way described below.
For sowing any seed, the best receptacles are 5-in. pots or seed pans, as these give good drainage and can be easily moved when necessary. The pot should be thoroughly cleaned and then crocked and filled carefully. A large crock, convex side uppermost is placed over the hole and covered with about an inch and a half of broken pot crocks or gravel, which, in turn, is covered with moss or fiber to keep the crocks free from soil.
Compost is filled in each pot and evenly filmed to within about half an inch on top. This last part rather depends on the size of the seed. Allow room to cover the seeds with their own depth of soil and leave a quarter inch space for watering. This space is smaller at this stage than for later watering because the seedlings need to be as near to the light as possible to prevent them from becoming "drawn" and leggy.
The seed should be sown thinly, covered and then watered by plunging the pot to the rim in water until the water begins to appear on the surface. The pot is then covered with a sheet of glass and brown paper and placed in a cold greenhouse, cold frame or on a windowsill.
Turn the glass over each day to prevent condensation dripping on to the soil surface, and remove the paper as soon as the seedlings begin to appear. Water when necessary by plunging the pot as described above. The glass is increasingly raised on a label as the seedling's leaves develop, and it is finally removed altogether.
2. Growing Bonsai From Seedlings
Town dwellers or owners of very small gardens may well not wish to use space for stratification and various pots of germinating seedlings. Starting bonsai from seedlings cuts out much trouble and, of course, can save as much as two years in time.
Seedlings of many species can be collected with very little difficulty, e.g., beech, sycamore, horse chestnut, holly and oak and less often some of the conifers. It is not generally the custom of nurseries in this country to supply very small seedlings, but by visiting the nursery personally, it is sometimes possible to select what is wanted.
The best time to collect or select seedlings is in early spring just before they start into growth. When selecting, try to imagine the style and shape for which they are intended. Look not only at the trunk but also at the branches or buds from which they will be formed. Above all choose a healthy plant, as it is unwise to pick out a small and possibly weak specimen, thinking that it will need less time spent on it to dwarf it.
In order to ensure that selected seedlings grow on with little or no check, great care should be taken when digging them up. Use a trowel or small spade and lift the seedling with a good ball of soil around the roots. If the soil is at all dry, it would be worth giving it a good soak and waiting a few moments for the water to penetrate the soil.
As soon as the seedling has been lifted, the roots should be wrapped in a damp sack or, better still, strong polythene. If the seedling has to remain unspotted or unplanted for any length of time, after wrapping the roots the whole plant may be put in a polythene bag to conserve moisture in the leaves and so prevent wilting. Readers should not go digging in search of seedlings or wild plants on private or public property without permission.
Following subjects may be raised from seed or seedlings: (ones in bold denotes easier subjects)
- Pinus (leave seedlings in seed pot for one year)
3. Growing Bonsai From Cuttings
Young plants can often be obtained more quickly by taking cuttings than by raising them from seed, and so for many subjects, it is the best method to use. Cuttings also give young plants of exactly the same character as the parent, whereas seed will give quite a variety of types, some of which may not be suitable for bonsai work.
Here we will discuss stem cuttings (cuttings may also be made of leaves and roots), and these may be soft-wooded, half ripe, or hard-wooded. Half-ripe and hard-wooded are the types which are most frequently used for the propagation of trees and shrubs chosen for bonsai work.
Small shoots of the current season's growth of about 3-4 inches long are torn off their "parent" stem complete with a heel, which is, in fact, part of the main or parent stem from which the shoot is growing. Half-ripe cuttings may also be made without a heel by cutting off the top three or four inches of the shoot just below a leaf joint or node, provided that the shoot at this point has begun to get firm but not woody. The bark should have become tough and darker in color than at the growing tip. The lower leaves are removed before insertion to prevent them from decaying, and thus possibly damaging the stem. All cuts, when trimming the heels of cutting and removing leaves, should be made carefully with a very sharp knife or razor blade. Rough cuts and damaged tissues may cause the cutting to decay before the rooting can start.
When only a few cuttings of each kind are taken, these are best inserted in a 5-inch pot which has been given a generous layer of ‘crocks’ and then filled with sand or vermiculite which retains moisture well. Large quantities can be inserted in rows in boxes (kipper or sultana boxes are most suitable) prepared in the same way as the 5-inch pots.
Each cutting is inserted firmly, approximately one-third of its length being buried. After insertion, a thorough watering is given. The pots are placed in a cold frame and kept shaded in hot sun until rooting starts. The boxes should be covered with a sheet of glass, and newspaper if sunny. In this case, the tops of the cuttings will need to be approximately one inch below the rim of the box. When rooting has taken place the glass may be removed gradually to increase ventilation.
This type of cutting is made when the season's growth has finished and the shoots are firm right to the tip. With deciduous subjects, it is usual to wait till the leaves have fallen.
As a rule, these cuttings are made from 9 to 12 inches long as they must be fully ripe and strong as they have to stand the rigours of the winter. A heel may be kept and trimmed and the cutting should be cut to the required length at the top immediately above a dormant bud.
These cuttings may also be made without a heel by trimming the shoot just below a bud. If the upper part of a shoot is used, it is advisable to remove the tip in order to encourage stronger growth in the spring following the insertion of the cutting. The ground should be forked carefully, and then a narrow slit or gully is cut with a spade to a depth of 5 to 6 inches. A layer of coarse sand one inch deep scattered in the bottom of the gully will help the root growth, especially in the heavier soils. Each cutting is pushed into the soil in the gully, buried to between half and two-thirds of its length.
The soil should then be leveled and thoroughly firmed with the heel of the shoe or boot at the time of planting, and again in the spring, as frosts will have loosened it during the winter. They often remain dormant, forming only a callus, until spring when roots will form, and signs of growth can be seen in the leaves. Plants raised from hard-wood cuttings remain in situ until the following autumn—October or November—when they are potted.
As far as conifers are concerned, these are not always easily raised from cuttings. The high-resin content of Pinus, Picea and Abeis seems to hinder the formation of the callus from which the new roots grow, so these are more easily grown from the seed. Cupressus and Juniperus, on the other hand, are not so resinous and the best results are obtained from semi-ripe cuttings taken in June or July; half of each cutting should be ripe. These cuttings may well need to stay in the rooting pots until the following spring before being potted.
Quicker and better root formation can in many cases be brought about by the use of rotting hormones. These hormones are made in various strengths, which should be related to the type or condition of the cuttings being made. One of the easiest to use and the best tried is "Seradix" B powder which is available in three strengths—pink for soft cuttings, white for half-ripe cuttings, and grey for hard-wood cuttings. A very complete list of plants suitable for each strength is supplied with each tin of powder, and the simple directions should, of course, be followed carefully.
Holly may be male, female or bisexual (having both male and female flowers on the same plant) and of course, for bonsai work, the bisexual is the type required if bonsai is wanted for its berries as well as attractive foliage. In the case of male and female plants, the berries will not form unless the female flowers are cross-pollinated by the pollen from male flowers; this could naturally be a big difficulty for a town -- or flat dweller. It is for this reason that the Ilex aquifolium appears in the list below, for if a holly tree is known to be bisexual, identical plants may be produced by cuttings. Some forms of I. aquifolium are bisexual and it is from these that cuttings should be taken.
Chaenomeles is included in the list for both cuttings and layering, and indeed nursery men usually keep what are known as "stool" plants and the young shoots produced each year are layered. It is, however, possible to raise plants from hard-wood cuttings, though the percentage of success is less; in this particular case cuttings with a heel are usually more successful.
The following subjects are often raised from cuttings (ones in bold denotes easier subjects)
- Chaenomeles: hard-wood cuttings
- Cotonoeaster: hard-wood cuttings
- Forsythia: Semi-ripe and hard-wood cuttings
- Prunus subhirtella: Semi-ripe cuttings
- Salix: hard-wood cuttings
- Tamarix: hard-wood cuttings
- Juniperus: Semi-ripe cuttings
- Cryptomeria: Semi-ripe cuttings
- Ilex aquifolium: Semi-ripe and hard-wood cuttings
4. Growing Bonsai By Layering
Some plants whose shoots can be brought down to the soil may be increased quite easily by this method. A healthy shoot is selected; usually, a one-year-old gives the best results, and a slit is cut in it about one inch long from the parent plant to tip at a place where the shoot will touch the ground. It is then pegged down in such a way that the slit is kept open and the shoot firm. Finally, the slit portion and peg are covered with two to three inches of good sandy soil which is firmed and watered. A stake is sometimes necessary to keep the shoot firm, thereby avoiding damage to any young roots as they form.
Spring, when growth has started, is the best time to layer and most plants will have formed good roots by the autumn. Two or three weeks before removing the new plant for potting, the shoot should be cut on the parent side of the split.
Azaleas, Chaenomeles, Jasminum nudiflorum, and lilac are all quite readily reproduced by layering. Sometimes old plants of Prunus amygdalus (almond) and P. Persica (peach)are found on their own roots, and these roots often send up suckers which can be dug up to form new plants. Nowadays, selected varieties of both of these prunus are usually on plum stocks, in which case the plum suckers are not of interest to the bonsai grower. However, people have sometimes have been successful with sowing the stones from the fresh fruit, and suckers from any such plants are well worth digging up.
5. Growing Bonsai From Wild Plants
The Japanese bonsai enthusiast is always on the lookout for plants growing in the wild which could be potted and grown on as bonsai; these plants will be seedlings of trees or shrubs rather than wild flowers. Occasionally one may find a specimen with an interesting shape—gnarled, twisted or windswept; but owing to the fact that these plants are usually not young, they are not easy to transplant and re-establish in containers. Their roots have often penetrated the soil to considerable depths, even if the soil is poor, and one cannot avoid causing fairly severe damage to the plants when lifting them.
It is quite easy to find seedlings of a number of trees, particularly sycamore, hawthorn, holly, silver birch, beech and various willows. Naturally, the smaller the plant in question the greater the chance of success in re-establishing it in its new environment.
When digging up a wild plant do it, if possible, before growth starts in the spring, and retain as much as possible in a "ball" around the roots by enclosing them in a piece of sacking or polythene. One may, of course, find good wild specimens when they are out walking or on holiday at any time of the year, and if this happens they will often find it is possible to re-establish a plant even if it is in full leaf.
A little extra aftercare will be necessary; if possible, soak the ground thoroughly before digging up the plant and water the soil when it has been planted or potted. It will be worth keeping the plant shaded from the sun and syringing it copiously two or three times a day to cut down the loss of moisture from the leaves which if excessive will cause wilting. The next stage is to plant the selected tree in the open ground in good soil that has had peat or other humus added to encourage the development of a new and fibrous root system.
After a year in this site, and if the plant has recovered from the disturbance, it may be transferred to a suitable container. If the wild tree selected is a relatively small specimen with a fibrous root system, it will be possible to plant it into a pot rather than in open soil. It is advisable to use an ordinary flower pot rather than the eventual bonsai container; the greater soil capacity will facilitate a quicker recovery. After a growing season, the plant will have recovered from the disturbance and grown new fibrous roots.
Bonsai grown from selected "old" wild plants will need very little training; just enough to maintain the shape. As far as the younger specimens are concerned, all training should be delayered for a year. If wire is applied too soon, it may cause branches to die or even cause the death of the plant.
Now that the main ways of starting a bonsai specimen have been discussed, the reader will realize that care, patience and time are needed for the start of a successful specimen. As mentioned before, it is now possible to buy bonsai that have had the initial training done. This, of course, leaves times and trouble, but at the same time removes one of the chief delights of bonsai growing. Naturally, a bonsai that one has raised and trained right from the beginning is going to give the greatest pleasure and satisfaction.