• Skip to main content
  • Skip to footer

Bonsai Tonight

An educational website about bonsai development

  • Blog
    • How-to Guides
  • Podcast
  • Shop
    • Bonsai
    • Books
    • Soil
    • Soil (wholesale)
    • Supplies
    • Tools
    • Video Consulting
    • Northern California Bonsai Resources
  • About
    • Workshops

Watering deciduous bonsai – part 1

July 14, 2020 by Jonas Dupuich

The easiest way to tell if a deciduous tree needs watering is to look at the soil. For most deciduous species, I want the soil to start drying out before watering. Here’s what this looks like.

Moss

Moss covering the surface of the soil

Wet soil

Wet soil – no need to water

Moss

Later the same day

Partially dry soil

Soil is starting to dry out – time to water

Different species have different water requirements, but in general, deciduous species need more frequent watering than conifers, and some species like Japanese maples and stewartia need more frequent watering than other deciduous species.

Over the years, I’ve found that the most important factor in watering deciduous bonsai is finding the best spot in the garden for each tree to grow. Because deciduous species show signs of damage after a short time without adequate water, the better suited a tree is to its environment, the easier it will be to keep it healthy.

When deciduous bonsai get too much or too little water, they typically let us know about it. The most common sign of underwatering is wilted foliage.

Wilted foliage

Wilted foliage on Chinese quince

If a tree goes too long without adequate water, the tips can turn brown, and in some cases, foliage will show signs of sunburn by discoloring as in the example below.

Dry foliage

Sunburned leaves with dried tips on Japanese maple

Healthy foliage

Healthy foliage from the same tree

Overwatering can be hard to diagnose as the symptoms are similar to those caused by underwatering. The best guide to whether the problem is caused by a tree staying too wet or too dry is to think back on your watering habits and determine if the soil was usually wet when you watered or whether it dried out between waterings.

Signs of overwatering

Likely signs of overwatering on a shishigashira Japanese maple

Keeping deciduous bonsai too wet can also lead to fungus problems. One of the most common fungi is powdery mildew. The best way to prevent it is to avoid overhead watering trees for which it is a problem.

Powdery mildew

Powdery mildew on Japanese maple

Once you’re familiar with the signs of over- or underwatering, it’s easier to know what changes need to be made to keep your trees healthy.

Of course, making changes can lead to new challenges. This spring was warmer than usual, and as a result, some of my azaleas started showing signs of stress (more yellow leaves, fewer new shoots). To reduce the stress on these trees, I switched my shade structure from 30% shade cloth to 40%. (The number refers to the percentage of the sun that is blocked by the cloth; 40% shade cloth lets 60% of the light through and blocks the rest).

Shade cloth

30% shade cloth on the left, 40% on the right

Many of the azaleas in the shade structure started producing new growth within a few weeks of making the switch, but I started seeing less desirable changes in some of my deciduous trees.

Species like trident maple and Korean hornbeam don’t need as much shade as Japanese maple or stewartia, yet all of these species grow under the same shade structure in my garden. After making the switch from 30% to 40%, the new leaves started growing much larger on my hornbeams.

Large leaves on Korean hornbeam

Large leaves on Korean hornbeam

To keep the leaf – and intenode – size in check, I need to make sure these trees start receiving more light.

There’s far more to say about the water needs of deciduous bonsai, so tune for Friday’s post: Watering deciduous bonsai part 2 – top dressings.

Video Consultations Now Available

Have questions about your trees? Schedule an appointment to discuss strategies for improving your bonsai. Learn more about Bonsai Tonight’s Video Consulting.

English-language consultations are available worldwide.

Subscribe to Bonsai Tonight

New Posts Delivered Every Tuesday and Friday

Success! Now check your email to confirm your subscription.

There was an error submitting your subscription. Please try again.

We won't send you spam. Unsubscribe at any time. Powered by Kit

Filed Under: Bonsai Care Tagged With: Deciduous, Watering

Previous Post: « Watering conifers
Next Post: Watering deciduous bonsai – part 2 »

Reader Interactions

Comments

  1. Shinya Miyakoshi says

    July 14, 2020 at 8:33 am

    Good Morning Jonas,
    I enjoy reading your post with my morning coffee.
    I have a tendency to over water my trees. Do you recommend using Soil Moisture Sensor Meter?

    • Jonas Dupuich says

      July 14, 2020 at 3:17 pm

      Thanks Shinya! I haven’t used moisture meters as they don’t always provide accurate results with bonsai soil, but they can work well in some circumstances. Will try to write more on the topic!

  2. Charles Mosse says

    July 14, 2020 at 9:21 am

    The watering posts are perfect timing and well grounded methods that you and other bonsai and nursery professionals have been telling us and improving on like the use of sphagnum moss. Thanks so much for getting into the subject of watering. Appears so easy but there are so many nuances to it to make it more effecetive to improve the look and health of our trees.

    • Jonas Dupuich says

      July 14, 2020 at 3:18 pm

      Thanks Charlie! I wish it was easier, but it’s one of those bonsai tasks that remains interesting over the years!

  3. Yaroslav says

    July 14, 2020 at 1:21 pm

    Do I understand correctly that palmatum maples can get burned tips with both insufficient and excessive watering? Or are there differences in burns?

    • Jonas Dupuich says

      July 14, 2020 at 3:13 pm

      That’s exactly right. And while there some signs that look more like too dry than too wet, but the best clue is your recollection of whether the tree is typically wet or dry when you water.

  4. Vance Hanna says

    July 14, 2020 at 6:01 pm

    Jonas,
    Thanks for your most diligent work . I must say I do enjoy your daily posts and reflect on my collection accordingly.
    I look forward to meeting you . Sincerely

    • Jonas Dupuich says

      July 15, 2020 at 6:17 am

      Thanks Vance – I hope your pines are doing well!

  5. marc shaw says

    July 15, 2020 at 8:46 am

    Why would trident maples put out leaves all bunched up instead of the more usual leafing along a branch?

    • Jonas Dupuich says

      July 15, 2020 at 1:26 pm

      Hi Marc – good question. Tridents will often put out clumps of leaves while they’re gaining strength and then send out runners when the tree is stronger. This is usually more pronounced on mature trees but I’ve seen it on young trees too. Does it sound like this could be the case? Feel free to post the question with a photo to the forum: https://ask.bonsaitonight.com/

Footer

Follow Bonsai Tonight

Subscribe

Instagram ● Facebook ● Twitter
  • Blog
  • Podcast
  • Shop
  • About

P.O. Box 6560, Alameda, CA 94501 · 510-915-2025 · jonas (at) bonsaitonight (dot) com

© Copyright 2009-2025 Bonsai Tonight · All rights reserved · Privacy · Log in

This website uses cookies to improve your experience. You can opt-out if you wish. Accept Decline Read More
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Non-necessary
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
SAVE & ACCEPT