Please read the following 3 articles which are full of useful and informative advice on how to care for some of the most popular trees in the world of Bonsai gardening.
Bonsai gardening is best enjoyed when you really can appreciate why you are doing something and what you are doing it for. Being aware of specific factors affecting certain trees is invaluable.
Bonsai - How To Care For: Blue Junipers
Junipers are, along with pine, another of the common species sought by beginning bonsai enthusiasts. And for good reason: it’s a beautiful species that tolerates a wide variety of conditions well.
Junipers enjoy full sun and tolerate moderately dry soil conditions. Soil shouldn’t be allowed to dry out completely, however. Copious amounts of water are fine, provided there is adequate drainage.
Feeding should be carried out every three to four weeks from early spring to autumn. Opinions vary, with some preferring organic fertilizers but this seems to be as much an ideology as a view based on good botanical science.
Man-made chemical fertilizers can be harsh, though, and should be used with care to ensure the proper proportions. Half-strength of 20-20-20 NPK (Nitrogen - N, Phosphorus - P, Potassium - K) is common. Avoid applying during the hot months or within a few weeks after repotting.
Repotting is a good time to trim roots, but gradual reduction is best. Cut off no more than 1/3. Trees younger than 10 years old should be repotted every two years, older ones every three to four.
Soil mixture is commonly 60% soil, 10% peat and 30% coarse sand, but there are many variations on the relative amounts and material. Loam, leaf mold and sand in equal proportions is a viable alternative.
Repotting is also a good time to carry out pruning of unwanted branches. Wiring is best done in late autumn, however, after the major growing season has tapered off. If carried out during active growing season results will come quicker, but careful observation is needed to avoid scarring.
Red spider mites are a common pest of this species. Look for yellowing foliage. Check under the branch for small spots. To double-check, hold a white sheet of paper or a tissue underneath. Sharply tap a branch without too much force. This should dislodge a few if they’re present. If they move, you know you have something you don’t want on your tree.
A home recipe of nicotine solution can be prepared by soaking tobacco in water overnight, but a commercial insecticidal solution will be more effective.
After the insecticide has operated for a day, spray the foliage with water daily during the growing season and allow to dry in full, but early sun. Full sun should be avoided for a few weeks right after repotting.
Bonsai - How To Care For: Maple
Maples come in a variety of sub-species, but all of them make beautiful bonsai trees. Slightly more difficult to care for, they are nonetheless greatly in demand by bonsai enthusiasts. Their leafy appearance is attractive, particularly in the fall when they turn to yellow and red, just as do the full-sized maples.
Some varieties thrive well as indoor plants, but for the most part bonsai trees are outdoor plants. Opinions vary about how much sun they require, but partial sun/partial shade is a safe bet with most types.
They survive winter well in the wild, but in bonsai form they require some care. Less water in the winter is called for and care should be taken that the roots don’t get any frost.
Copious watering in the summer is warranted, provided - as with any bonsai tree - there is good drainage. A little extra moisture isn’t a bad thing, though, especially for the flowering varieties. Maples like moist soil.
They adapt well to various styles, but the informal upright (shakan) may be best, given their leafy nature and somewhat brittle branches. It is possible to train them into the han-kengai (semi-cascade) and others, but extreme care must be taken to avoid splitting the trunk and branches.
Han-kengai can be achieved without wiring by a cord attached to a stake in order to curve the trunk. However, this form doesn’t typically occur in nature. Since traditional bonsai art aims at emulating nature on a small scale, this form is uncommon.
Feeding once per month is fine, with a slow-release fertilizer from spring to autumn. Taper off during hot summer months, though. An organic type works well, but Peter’s 20-20-20 is also a good mix. Hold off any feeding for a few weeks after repotting.
Since they can produce ample branches and leaves, root systems tend to grow accordingly to support them. Pruning, therefore, should be taken as a concerted project. For fewer branches and leaves, roots can be pruned more aggressively.
Branch pruning is best carried out in fall or winter when there are fewer or no leaves. This gives a clearly visible working area, leading to fewer mishaps. Maples heal better if pruning paste is used to seal the wound after branch removal.
Pinch back new growth during the active growing season to keep foliage to a moderate level. Remember you are creating a bonsai, where the goal is somewhat minimalist. A fully leaved tree looks more like an ordinary houseplant.
Wiring is less common with maples for a variety of reasons beyond the somewhat brittle branches. They acquire pleasing shapes with leaf and branch pruning without extra effort and they scar easily.
Like most bonsai trees, repotting every two years is a good practice. When replanting a mixture of 60% soil, 20% peat and 20% coarse sand will provide the correct drainage environment. This is best done in early spring, before buds have started.
Bonsai - How To Care For: White Pine
Though no bonsai is easy to train or care for, pine is among the easier species. More tolerant to drying, they adapt well to a pot and often require only regular trimming and biannual repotting.
In the wild, pine commonly grow to 50 feet or more with trunks that are a foot in diameter and larger. Yet they make excellent bonsai trees and look stellar in miniature form. Because of their naturally straight trunks and symmetrical branch arrangements they are well suited to the formal upright (chokkan) style.
In the chokkan style, the trunk is straight and rises vertically from the base, in contrast to the cascade (kengai) that is both curved and grows horizontally across the surface. The chokkan thus makes a good starter species for budding bonsai artists.
Bonsai trees are not a dwarf variety, but a full-sized species that has been carefully trained to emulate conditions in the wild on a very small scale. White pine bonsai, therefore, will have the same characteristics as the full grown variety.
White pine have blue-green needles that form in bunches of five, growing from a small bud. Branches grow in a circular pattern, looking down at the tree from above, with several levels around the tree at intervals up the trunk.
A healthy tree looks healthy, especially in the spring when new growth appears. Needles will be a brighter green and start lengthening. Full-sized pines can add two feet or more to their height during the season. You’ll want to remove or reduce some of the new shoots during this period every year or two.
Repotting can be carried out during spring but can wait as late as early autumn, after the summer heat has cooled.
During repotting ensure there is good drainage when you’re done. Pines tolerate dryer soil much better than over-watering. A mixture of 50% soil, 10% peat and 40% coarse sand works well for many, but there are many variations on the material and relative amounts.
Repotting is a good time for root trimming, but be conservative. Pines need a deep pot in order to grow a deep root system for stability. No more than 1/3 of the root should be cut off during the procedure.
Branch pruning is best carried out during late autumn.
It’s common for some of the needles to become brown and fall off in the summer. This needn’t be cause for concern unless the tree is diseased.
Check for large hemispheres of very dark growth on the branch that can indicate the presence of a tumor. If there are none, and only a small percentage of the needles are brown, the condition may well be normal.
Aphids and mealy bugs are common pests, but easily controlled by a commercial or home-grown mixture. Often a slight misting with a dilute liquid dishwashing detergent will take care of the problem temporarily. The needles should be misted with plain water the day after.
Pines can be watered daily provided there is very good drainage, but every other day is fine. Feeding should be done every two to four weeks from early to late spring and again at the end of summer to early autumn. This coincides with the pine’s active growing seasons.