How Often Should You Water a Bonsai in Autumn?

Your bonsai seemed thirsty every day in summer. Now the mornings are cooler, the days are shorter, and your phone still says, “Water bonsai.” Should you listen to it?

Take thirty seconds to check the pot first. In autumn, the best watering schedule is the one your bonsai tells you it needs. 💧

First, let the compost answer

Gently touch the growing medium at the surface and a little below it. If it still feels wet, leave the watering can where it is and check again later. If it is becoming dry, water slowly and thoroughly, allowing the water to drain from the bottom of the pot.

That sounds simple, but a shallow bonsai pot can be misleading. Its surface may look dry while the compost below remains moist. Equally, a quick shower may dampen the top without properly wetting a dry rootball.

The goal is to keep the growing medium suitably moist for your tree, without leaving its roots sitting in water. The RHS advises watering bonsai when needed and checking them throughout the year, including during dry winter spells. RHS Advice

Why autumn changes the routine 🍂

Your bonsai does not know what day of the week it is. It responds to its surroundings.

A pot on a sheltered patio might receive very little rain. One exposed to several cool, wet days may take longer to dry. Wind can dry a pot even when the air feels chilly. Indoors, a tree may dry faster once the heating comes on.

The tree matters too. An outdoor deciduous bonsai may slow down and lose its leaves naturally in autumn, while an indoor tropical bonsai has different growing conditions. Pot size, growing medium and placement all affect how quickly you need to water. RHS Advice

So how often should you check? Check regularly, particularly when the weather or the tree’s location changes. Water when the growing medium needs it, rather than automatically watering every few days.

The five-minute watering check

Before you pour, look for these clues:

1. Feel below the surface. Is the growing medium becoming dry, or is it still moist underneath?
2. Consider the pot’s weight. If you can lift it safely, notice how it feels after watering compared with when it is drying out.
3. Check where the water goes. When you water, it should soak into the growing medium and drain through the holes beneath the pot.
4. Look at its location. Has the tree been under a roof, in strong wind, in prolonged rain or near indoor heating?

Do this a few times and you will start to recognise your bonsai’s pattern. That is much more useful than borrowing somebody else’s watering timetable.

What if the water runs straight through?

If water immediately escapes down a gap at the edge of the pot, the middle of a very dry rootball may still need moisture. Apply water gently in stages and check that it is soaking into the growing medium. A watering can with a fine rose helps you water a shallow pot without washing the compost away. RHS Advice

If water pools on the surface or the pot stays wet for a long time, check its drainage holes and any decorative outer container. Empty a water-filled tray so the pot is not left standing in it.

Repeatedly soggy compost, a sour smell or a pot that becomes bone dry unusually quickly deserves a closer look. Work out what is happening with the growing medium and roots before changing your entire care routine.

Are falling leaves a watering warning?

Not always. If your outdoor bonsai is a deciduous tree, losing leaves in autumn may be part of its normal seasonal cycle. Do not respond to every fallen leaf with another watering. Check the tree’s species, the growing medium and the weather together. RHS Advice

A young seedling needs a particularly gentle stream of water so its roots and growing medium are not disturbed. Its little pot may also behave differently from a mature tree’s broad bonsai container.

One thing to do today

Feel just below the surface of your bonsai’s growing medium. If it is still wet, check again later. If it is becoming dry, water gently and make sure the excess can drain away.

That small habit is your autumn watering plan: observe first, water second. 🌱