A Guide To Watering Bonsai

Page 2 of 2

Page 2: A Guide To Watering Bonsai

Fitting Your Watering Schedule Around Work Hours

In the real world, many of us are away from home during the day and are not able to check or water our trees. To allow the tree to go without water for any length of time is disastrous and should be avoided at all costs. Get to know your trees; know which ones are likely to dry out during the day while you are away. Know which trees will dry out if the weather is forecast to be hot or windy. If there is a risk that a tree may dry out during the course of the day; water in the morning before you leave home. Despite what you may read, there is no reason to base your watering regime in the evening; try making your main watering time in the morning so that your bonsai are well-watered before the heat of the day, and then only water those that require it, in the evening.

The Effect of Soil on Watering Practices

The soil that your trees grow in has much influence on how frequently water is required and on how diligently you must water correctly. Organic soils containing peat or 'soil' are most likely to cause problems associated with overwatering; the soil is likely to retain too much water. Conversely it can be much more difficult to water thoroughly, as water will tend to run off the dry surface leaving the interior of the rootball dry.

If an inorganic soil is used, the risk of overwatering is greatly reduced. Inorganic soils containing akadama, turface, seramis, grit etc are water retentive enough to keep the soil moist for the duration of a hot summers day and also makes overwatering almost impossible.

How Should I Water?

When the tree does require water, it needs a thorough soaking; avoid just 'moistening' the bonsai soil, water it properly. Each time you water, it is important that the entire rootsystem and body of compost is properly wetted to avoid pockets of dry soil where roots could be left to dry out and die.

The Japanese have an adage for watering; 'For bonsai, it rains two times'. Water should be applied twice; the first watering wets the soil so that any dry soil particles will accept moisture better as they tend to shun water at first. Water should be applied all over the compost surface until it can be seen to run out of the drainage holes. The second watering should be left for 10-20 minutes by which time any previously dry areas of the compost will be ready to accept water. For a second time, water thoroughly all over the surface of the compost until water can be seen to run out of the drainage holes of the pot. The compost and root system should now be sufficiently wetted.

bonsai watering

Hoses and Watering Cans

If you use an overly concentrated a stream of water, the bonsai soil is likely to be washed out of the pot. For small bonsai collections, a small watering-can fitted with a fine rose is sufficient to water the soil thoroughly without displacing the soil. Otherwise use a hose fitted with a spray gun set to mist, shower or any setting that will not disturb the soil.

Suitable Water For Bonsai

Water your bonsai with plain tapwater. In areas where the tapwater is hard, occasionally watering with rainwater is useful to rid the soil of any build up of salts, but is not essential, unless the tapwater is particularly hard and white salt deposits start to appear around the pot or trunkbase.

Rainwater can be collected in a water butt attached to the downpipe of a shed or house, though it would be difficult to collect enough water to meet the needs of a large collection on a daily basis. Do not use water obtained from water softeners; many water softening systems increase the volume of salts diluted in the water to a bonsai's great detriment.

Watering By Immersion

Some bonsai sources will suggest watering a bonsai by immersing the bonsai pot in water for a while. This is not a recommended way of watering your trees. Watering by immersion is a mannerof getting water to penetrate compacted, very poor quality organic soils only.

If a bonsai needs to be watered by immersion, it will be particularly prone to the effects of overwatering and weak roots. If a vendor recommends that you water by immersion, suspect that this is because the tree is in poor soil and is therefore difficult to water properly. Also suspect that the tree will be weak, slow growing and very possibly have root-related problems. Make holes in the soil around the edge of the pot using a chopstick or similar, to allow water to penetrate the soil, and repot at the earliest opportunity (ideally during the following spring) into a better quality, preferably inorganic, soil.

watering bonsai

The author's daughter watering his bonsai

Other Watering Problems

Bonsai compost should always be free draining. Compacted, poor-draining composts can cause many of the problems associated with under/over-watering. Bonsai compost should be open enough to allow water to penetrate throughout and to ensure that excess water is able to pass out through the drainage holes immediately.

Compacted soils slow the penetration of water, which will tend to sit on top of the compost surface and run over the sides of the pot or down the inner edges. Once thoroughly wetted, poor quality bonsai composts can hold too much water and little oxygen, which can eventually lead to problems associated with over-watering.

Extra care should be carried out when watering trees potted in poor draining compost, that should then be replaced at the next repotting.