Probably the most essential, urgent and significant part of your care for the survival of your bonsai trees is watering.

How frequently and when a tree needs to be watered depends on a number of factors, but without attention to this your tree will die and very, very quickly? You cannot forget it, be you too tired or too busy; if the tree dries out for more than a few hours it will suffer and over a longer period, die.

The amount of water to give when and how often varies according to:-

  • the species of tree (do they by their very nature like to be wet, moist or almost dry?)
  • the size of tree, the size of pot - small pots dry out far more quickly than large deep ones
  • the time of year and the soil mixture
  • the length of time in the pot - containers full of roots dry out faster than newly potted ones; even when they are the same species and do not readily accept water; it just runs off the surface

A pot bound tree with no space to accept water. When watering this tree, most of the water will flow right out of the pot; the roots are so compact that the soil-mass won't absorb water easily. This tree needs to be root trimmed and repotted!

Excess roots trimmed and ready to replace in pot; water will then be absorbed. Follow a few basic guidelines and you will soon learn to recognise when a tree needs to be watered.

Water Your Trees When the:

  • soil gets slightly dry
  • this means you do not water your tree when the soil is still wet, only when it feels slightly dry. Use your fingers to check the soil about 1cm down. In time you will be able to see (instead of feel) when a tree needs watering.
  • watering is not just a routine

Make it part of your daily routine to check, especially in damp weather. In dry weather they will always need watering, in damp weather not necessarily so.


Use The Correct Well Drained Soil Mixture

The soil mix is a major factor in the frequency of watering (see section on soils). Trees in a good mix of Akadama, compost and grit should not become overwatered. However, if you buy trees in an unknown mix you need to watch them with particular care until you are able to repot into a better mix.

When To Water

There is no right time of day for watering. There are all kinds of strange old wives tales around suggesting you must not water when the sun is shining or during the hottest part of the day, never to water with cold water – trees are not that fussy. The rule is – water as soon as the soil gets slightly dry! Long spouted watering can with a fine spray to avoid too much pressure pushing out the soil.

How To Water

Water with a fine rose-head watering can or hose, with not too much pressure, so as to guarantee fine, gentle watering that does not displace the soil. Water from above and keep watering until water runs out through the drainage holes. Using collected rain water is better (as it doesn’t contain added chemicals), but when this is not available there is no problem in using normal tap water. If in a hard water area you may get a white lime deposit on the leaves - no problem but it will need wiping off if you plan to show your tree. Hose with fine sprinkling nozzle.

Automatic Drip System

These systems can very useful if you go away from home, but regular use may mean some trees get over watered and others under watered as pressures throughout the system often vary. It must be combined with a daily check of your trees. Automated watering systems can often be quite costly.

Watering Variables

There are many variables when it comes to watering bonsai trees. These are a few of the basic questions to ask yourself:-

Species of tree

This will depend upon the part of the world they originated from. Desert trees require a lot less water than those from tropical rain forests. Trees from high above the snow line would not expect water in winter months as in their natural environment they would be frozen all winter. Do they by their nature like to be wet, moist or almost dry?

Size of container?

Small containers dry out far faster than large ones.


Outdoors? Growing in the shade? Or sun?

Time in Pot?

Containers full of roots dry out faster than newly potted ones; even when they are the same species.

No matter the method of watering bonsai you select . . . water enough so the water flows through and comes out the drainage holes in the bottom of your bonsai pot.

Two final and much discussed questions.

  1. What about "dunking"? This was at one time promoted as a good way to water. Bonsai watering by immersion is not always a good idea. If your tree is completely dried out, it may be a good quick fix for one or two trees, but far too time consuming for a sizeable collection; frequent immersion can compact the soil. This can cause root damage. If you feel it is necessary to "dunk" on a regular basis (because water is not being absorbed otherwise) check your tree - it probably needs repotting or most probably it needs to be in a different soil mix. Coarse, fast draining type bonsai soil is not as problematic with dunking.
  2. Misting - is it of value to the health of the tree? Trees do not absorb moisture through their foliage any more than we can reduce thirst by putting our hands in water. What it can do though is reduce the rate of transpiration (loss of moisture through the stomata of the leaves) Misting with a very fine spray mist makes the foliage wet, builds up humidity levels and slows the evaporation rate, thus reducing moisture loss.

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