Basic Bonsai Tree Care

Bonsai trees are plants and like any other plants and trees they needs light, water, nutrients and the right temperature to grown.  These elements will be dependent on where you live and other factors such as position, weather and size.  If you live somewhere warmer then they usually grow faster so need more water and feed, somewhere cool and damp and they needs less water and better light.

Watering

As this is probably the single most common reason why bonsai trees die it seems apt to mention is first.

Bonsai trees need to be kept moist.  Too wet and they get susceptible to root problems.  Too dry and they cannot maintain cell structure and die.  It is about balance with watering and something you need to be aware of sometimes twice daily in hot summer and maybe weekly in winter.  Large flat pot will dry out faster than deeper ones large leaved trees will use more water than small leaved ones.  Try to avoid standing trees in water as watering from above is a lot more beneficial.  Submersion should only really be done if the tree has inadvertently dried out and there is risk of dry parts of the root ball.

Feeding

The majority of feeds are made up of three main elements – Nitrogen, Phosphorus and Potassium.  A basic understanding of these three elements will help you understand how to feed trees to get certain results and what feed to use at different times of the year.

Nitrogen is essential for leaf, stem and soft branch development.  If the tree is fed too much nitrogen then excessive green growth can occur but conversely if you want to increase branch structure and back budding the higher nitrogen can actually force this to happen.

Phosphorus is needed for good root and flower development.  It can stay in soil for up to three years to another benefit of repotting into new soil can be seen here.

Potassium or Potash helps the trees build sugars and starches so is essential for maintaining growth.  Flowering and fruiting trees also require potassium to develop.  Potash also encourages trees to harden off and develop hard wood.

In basic terms it can be seen that a balanced feed is best for trees that contain other trace elements for general health and development as a lot of bonsai soils are of very low nutrient content.  Adjusting the balance away from nitrogen in late summer effectively starts to reduce green growth and harden trees off for winter.  If trees have too much nitrogen stored in their roots due to late season feeding or high nitrogen feeds given before leaf opening then large leaves can develop on deciduous trees.

Balanced liquid feeds are good for smaller and indoor trees and are added to the water.  They have the disadvantage of washing out of free draining soil with outdoor trees though.

Slow release solid feeds are advantageous with larger and outdoor bonsai trees as you are confident that feed is getting released into the soil at a steady and consistent rate.

Light and Positioning

Bonsai need light to develop and photosynthesise.  They will also be healthier and have a better tendency to increase branch structures when they are open to more light.

Due to the East to West transition of the sun south facing always has the warmer temperatures and better light levels over a longer time but also can lead to very high temperatures in midsummer.

East facing gives early morning heat from the sun which can be bad for trees that have caught the frost as the smaller branches can thaw but the frozen root ball cannot release moisture so branch loss can occur.  If trees are allowed to freeze then you need to be wary of the early morning sun.

West facing has the evening and long summer light and finally north facing can have low light level and subsequently lower temperatures which can be used to advantage to keep trees dormant on warmer winter days.

Care needs to be taken when positioning indoor trees as sites such as above radiators and in windows with full sun can produce very dry conditions very fast and trees can struggle to cope.

Pruning

Pruning has two major concepts.  One is to maintain the shape and aesthetics of the tree and the other to allow light into the branches to encourage healthy growth and branch development.  Deciduous trees are very forgiving and back bud, growth new branches and tolerate heavy pruning more readily than evergreen trees.  In the growing season it is beneficial to keep some green growth on each branch when pruning heavily to keep the sap flowing through the branches and encourage re growth.

Most trees will tolerate the thinning of the foliage to allow light inside the branch structures to encourage back budding and this is why a lot of bonsai have delicate leaf pads.

Pruning can be done whenever it is needed but late season pruning on deciduous trees can encourage soft green growth which is not ideal heading towards winter but this can be control with low nitrogen feeds.

Temperatures

These are pretty tree specific but essentially fall into two main groups – hardy and none hardy or tropical and subtropical which are roughly the outdoor and indoor class of trees.  Indoor trees do benefit from periods outside in warm weather but be careful they do not get damaged by cold nights. 

Outdoor trees do struggle inside as they often find it too dry and in winter it can be very damaging to try and keep a deciduous tree in leaf by bringing it into the house.  The occasional mild frost is often harmless to outdoor trees but prolonged and severe weather can cause die back of small branches or total tree loss.

Repotting

This is covered in one of our other care guides but basically bonsai are repotted to keep then growing and healthy.  You will struggle to water a compacted root ball effectively and the roots can get disease and root rot due to the lack of oxygen.

Bonsai are kept in their unique style by pruning not allowing getting pot bound.

Younger trees usually need repotting every year and older trees should be repotted as they need it but at least every 3 years to prevent the soil getting stale and salt residue building.

Basically...

Keep your bonsai moist, fed and with good light levels and it should thrive.

Our contact details are available on line at www.yorkbonsai.co.uk should you need any advice or assistance.

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