Watering Bonsai

I once read "watering bonsai trees takes years to learn".

How strange, I thought. Why would it ever take so long to learn such a simple thing?

The truth is, watering bonsai is not as simple as it may sound.

We are bombarded with instructions that vary so greatly, no wonder the novice is confused.

The following statements are a few examples of such varied watering instructions.

From an HGTV program on bonsai:
“Bonsai likes it on the drier side, so don't over-water.”

From an early U.S.D.A. brochure:
“Water your bonsai every day.”

From a bonsai nursery (not to be named):
“Water your bonsai every three days.”

They cannot all be right!

Watering Variables

There are many variables when it comes to watering any container plants. These are a few of the basic questions to ask:

• Species of plant – Do they by their nature like to be wet, moist or almost dry?

• Type of potting soil - Is it coarse and fast draining? Or, is it heavier and drains slowly, and therefore stays wet longer?

• Size of container? – Small containers dry out faster than large ones.

• Time in Pot? - Containers full of roots dry out faster than newly potted ones; even when they are the same species.

How Often?
What is the Answer?

Be wary of instructions to “water every day” or “every other day” or “every third day” etc.!

Watering bonsai instructions should read something like “keep evenly moist”, “keep wet” or “allow to dry out a little between waterings”.

Watering bonsai too much can be as big a problem as not enough. It’s important that plants are not over-watered. Be especially careful with succulent plants such as bonsai Jade.

How often should you water?

Not everyone will like this answer, however, the answer is water as needed for the specific type of plant you have!

Ezo Spruce bonsai in National Collection
Washington, D.C.

As you get to know your bonsai, you will be able to just look at them or pick them up and know whether they need water or not.

How To Water Bonsai

Outdoors, hand watering is best. I liked to use the hose with a watering wand.

It's gentle, doesn't knock soil out of the container and has an on/off valve. It's especially valuable when you ask someone else to water!

Bonsai by Dan Barton

Hand watering is the ideal. If you only have one or a few bonsai, it should work. Water enough so the water flows through and comes out the holes in the bottom of your pot.

To be sure all soil is moistened, water twice. Allow the first to 'sink in', then go back and water again.

Some of us who have many bonsai (perhaps too many), have automatic irrigation systems of one type or another.

The drip system on a timer is especially popular.

In Miami, I had a timed overhead sprinkler system (leftover from my nursery days.)

When you develop a large collection or have a nursery, automatic systems are certainly an option. I ran my system once a day in winter and twice a day in summer. I also varied the length of time for each session.

During the rainy season, I often turned it off and watered by hand.

Automatic irrigation is not without problems.

They do break down, can be inconsistent in different zones, create too much water when it rains and get clogged up from time to time.

What About "Dunking"?

Watering by immersion is not always a good idea. If your tree is completely dried out, it may be a good quick fix. However, frequent immersion can compact the soil. This can cause root damage.

If you find it is necessary to "dunk" on a regular basis (because water is not being absorbed otherwise) ... your bonsai may need repotting, AND most likely in a different soil mix.

Coarse, fast draining soil is not as problematic with dunking.

Daily Inspection

Did an animal knock over a tree? Was the wind really bad last night? Did the water miss your favorite small bonsai? What are those funny looking bugs?

Watering bonsai every day may or may not be necessary. However, bonsai do need daily inspections!

Where to Go From Here

Top of Page

Leave this Watering Bonsai page and go to general Bonsai Care and don't miss the very important Bonsai Soil page.