Maintaining Bonsaii

Bonsai is the art or aesthetic miniaturization of trees resulting in the beautiful, aged wonders that we all look at in awe. Although beautiful bonsai may take many hours of patient cultivation, they are actually quite easy to care for and maintain and make an impressive focal point in a garden or on a patio.

POSITION
Bonsai are outdoor plants and generally prefer morning sun with protection from afternoon sun in summer. Filtered sun in the afternoon would be suitable but if leaves begin to show stress, the sun is too strong. Given the variety in species however, each tree will have different requirements so consult the plant label for full sun and shade requirements. Bonsai can be brought inside for a few weeks but would never thrive if kept permanently indoors.

Bonsai are grown to look stunning from all sides so if a bonsai is placed against a wall, it should be turned every few weeks to ensure that the new growth stays uniform and the overall shape is maintained.

Although many bonsai look like they have been windswept, in fact they should be protected from wind and especially salty air. Avoid keeping plants on hot bricks or concrete which can burn the roots in the very shallow pots.

WATERING
Watering bonsai correctly is the most important thing to learn as their pots are so small and dry out quickly. Like all plants, most trees need more water in summer than in winter and the more leaves on a tree and the larger they are, the more water required to keep them lush and healthy. The weight of the pot is a good indication of whether a bonsai needs to be watered.

Avoid watering a bonsai with a garden hose which will only wash out the soil in the pot and any moss or pebbles sitting on the surface. A small watering can would be suitable but apply the water gently.

Water gently once and let the water settle before watering again a few minutes later.

Alternatively, place the bonsai pot in a tub of water ensuring that the water is deep enough to cover the soil surface. Leave the pot for a few minutes until the air bubbles stop coming from the soil and then remove to drain. Adding a teaspoon of Seasol to the water will provide extra nutrients that will encourage strong roots and healthier growth.

In winter, reduce the amount of water provided and be especially careful with deciduous trees with no winter foliage as these require very little water. Some people mist their bonsai trees but this is not a substitute for watering at any time of the year.

FERTILISING
Although small, bonsai do need to be fertilised. As with all plants in pots, they only have access to the nutrients that they are given within the soil and if these are depleted, the plant just can’t thrive.

If using liquid fertiliser, bonsai should be fertilised every two weeks during the growing season of spring and early summer and then twice in autumn. With deciduous trees, wait to start fertilising in spring until a few weeks after the leaves have opened and stop when the leaves start to change colour again in autumn.

Low nitrogen liquid fertilisers applied at half strength with alternate applications of Seasol will produce strong plants without too much growth. Applying a fertiliser that is too high in nitrogen will result in long internodes on the stems and leggy growth. Bonsai fertilisers are available and would make it easier to ensure correct applications.

Even easier is to use slow release fertiliser such as Osmocote Trees, Shrubs & Citrus. Apply once in spring and again in early autumn but don’t sprinkle over the surface as they will simply fall off. It is better to make a few holes along the inside edge of the pot and drop in a couple of fertiliser prills. Supplement this with Seasol every two weeks.

PRUNING
Pruning bonsai is an art and will help to develop patience. It is an essential part to maintaining the shape and size that was so attractive about the tree when first purchased.

Deciding when to prune does depend on the variety of tree and choosing which branches to cut is very much down to the shape of the bonsai itself. Don’t rush and cut the branches too early or at the wrong time. Although the tree will recover, it will take a while.

When the new shoots of a tree have grown and appear more “woody” it is time to prune to maintain outward growing horizontal branches with groupings of leaves to imitate a mature tree. Generally, the shoot should be cut above the leaf from where the new shoot is to grow taking in to account that it will grow in the same direction as the leaf. Some bonsai will require two trims a year and some just one. Consider visiting a specialist bonsai nursery for expert assistance and advice on pruning all varieties of bonsai trees.

PESTS AND DISEASES
Like all plants, bonsai are susceptible to disease and pest attacks but diagnosing the problem is not usually too big a problem. Bring in a leaf sample or even the whole tree to your closest Better Pets and Gardens store and we can assist in identifying the issue. It is important to remember that continuous problems with pests and diseases are a good indication that the bonsai is under stress from either growing in the wrong position, lacking in nutrients or not being maintained properly.

Mealy bug are small, white “fluffy” insects which sit in the crevices of stems and nodes and even in the roots sucking the sap from plants. The new growth will become distorted and if left to get out of hand, the tree will show stress. Treat with Confidor or other suitable insect spray.

Scale is not uncommon on the leaves of bonsai and occasionally on stems. If there are just a few, they can be scraped off with a finger nail but where there are too many, spraying with White Oil or Pest Oil will suffocate the little insects that sit under the shell. Do not apply in the heat of the day however as the oil content will burn the leaves.

Aphid may appear on new growth and are easily dealt with by using Confidor or other suitable insect sprays. With aphid, and in fact mealy bug and scale, ants are often present as they “farm” these insects to feed on the sugary nectar that they excrete. It is important to treat the ants as well as the insects otherwise the problem will not be resolved.

Don’t assume that yellow leaves are the result of a disease when in fact, this is more likely to be from over-watering which is almost always the cause of leaf fall in the wrong season.

RE-POTTING
Bonsai that are less than ten years usually require re-potting every two years and some more vigorous varieties may even need to be done more often. Soil that becomes difficult to water or bonsai where the plant starts to push up out of the pot have become root bound and require re-potting.

Bonsai require special soil and should never be potted in all-purpose potting mix or soil from the garden. It is best to seek advice from a specialist bonsai nursery before re-potting and they may even offer a re-potting service.

GENERAL MAINTENANCE
Keeping a bonsai pot weed-free is very important as there is so little soil and the tree won’t cope with the competition for nutrients. However, the moss that is often on the trees and over the soil is naturally grown to help retain moisture and provide protection from heat and wind. From re-potting the time for this moss to fully cover is about six months. Misting the moss daily during hot weather will allow it to stay lush but be careful not to water-log the tree in the process.

Wire is often used to maintain the shape of branches and often should remain on the tree for at least 12 months until the desired shape is achieved. Keep an eye on these to make sure that they don’t begin to cut in to the bark of the tree. When necessary, carefully remove or adjust the wire by unwinding and re-winding.