The basic rule for bonsai watering is to water when the soil begins to dry, until water drains from the bottom of the pot. This guide covers checking the soil, watering each pot, adjusting to the weather and misting the foliage.
When to Water Your Bonsai
Check the soil each morning and water when the surface begins to dry. If it is still moist, check again later. Water before the soil dries out completely.
Akadama is darker when wet and turns paler as it dries. Compare its color just after watering with its color as it dries, so you learn to recognize the difference.
If moss hides the soil, feel an exposed area, such as near the rim of the pot, with your finger. If you can lift the pot, learning the difference in weight before and after watering can also help.
How Much Water and How to Water
- Use a gentle spray. Use the rose attachment on a watering can or a fine-spray hose nozzle. Keep the flow gentle enough not to wash away or displace the soil.
- Water the whole soil surface. Reach the back of the pot and beneath the foliage, rather than watering only one side of the trunk.
- Water until it drains from the bottom of the pot. A second pass after a short pause helps water soak through the pot.
If you use a saucer, empty the water that drains into it. If water collects without draining, check that the drainage holes are not blocked.
Watering in Different Conditions
Japanese seasonal references are for outdoor bonsai in lowland areas around Tokyo. Use your local weather and the tree’s growth to decide how often to check the soil.
| Conditions | What to do |
|---|---|
| Active growth Japan: spring to autumn | Check the soil every morning. Watch for faster drying as new shoots and leaves grow. |
| Hot or windy weather Japan: summer heat | Check in the morning, at midday and in the evening. Water when the soil begins to dry. |
| Cool weather or dormancy Japan: winter | Keep checking daily, even if the soil dries slowly. In frosty conditions, water during the warmer part of the day, once any frozen soil has thawed. |
Decide whether to water by checking the soil every day. If it is still moist, wait. If it is dry, water.
Soil dries faster in small or shallow pots. Pots exposed to strong sun or wind also dry quickly, so check the soil in each pot before watering.
In hot weather, water dry soil without waiting until evening. Water left inside a hose can become hot in the sun. Run the hose away from your pots first, and check that the water is not hot before watering.
Why and How to Mist the Foliage
Misting means spraying water onto the leaves and branches. It rinses away dust and dirt and briefly raises humidity around the foliage.
- How: Use a fine spray from a watering can, hose nozzle or mister to gently wet both sides of the leaves. If the tree is flowering, keep water off the flowers.
- When: In hot weather, mist in the morning or in the evening once it has cooled down. In cold weather, avoid early mornings and late afternoons when there is a risk of frost.
Misting is not a substitute for watering the soil. Even when the leaves are wet, check the moisture in the pot.
Common Watering Questions
Do I Need to Water When It Rains?
Light rain may not reach the soil, especially where foliage covers the pot. Check the soil even when it is raining, and water if it is dry.
What If the Leaves Wilt but the Soil Is Still Wet?
Do not add more water straight away. Check whether water can drain from the pot and whether the pot has become hot. If you have recently repotted the tree, consider what has changed since then. If you cannot identify the cause, ask the nursery you bought it from for advice. Share photos of the whole tree, the leaves and the soil, along with notes on its location and watering.
How Do I Water While I Am Away?
If the soil is likely to dry while you are away, arrange for someone to water your bonsai or use an automatic watering system. Tell whoever is helping which pots dry fastest. Test an automatic system before leaving to make sure water reaches every pot.
For equipment, see our guide to choosing watering cans and hose nozzles.
For sunlight and airflow, see Bonsai Placement. For daily care and seasonal work, see Bonsai for Beginners in our Bonsai Guide.
The videos below also cover bonsai watering.
