Automatic watering systems for bonsai?


Well, mostly no.

I used an automatic system for bonsai while living in Arizona. I did not have any dreadful experiences, and I only used it on trips, but I learned some of their shortcomings from that and from watching others use them.


Reverse osmosis? Bah. I think this is the ticket.

The main reservation with automatic systems is that each species needs different care, and then each specimen will require slightly different care as well. Watering bonsai is an art. And a system can’t manage an art.

An automatic watering system for bonsai is always a very distant second choice. Watering by hand is always preferred. BUT, a system can be useful for a very specific purpose, for instance, to water during the middle of a hot day while you’re away at work. Whenever you can, water bonsai by hand.

There are two arguments going on here, one about the safety of automatic watering systems, whether they can be relied on, and another about how well they take care of our trees. Neither are impressive.

Try to avoid relying on automatic systems, exclusively. If you must use them monitor them frequently, and when gone on vacation have someone, a neighbor, anyone, to check that it is working while you are gone. Too many glitches make their sole use a cautionary tale, with power outages when gone on vacation the worst (I know more than six people who’ve lost entire collections this way).

What are the risks of a system to tree health? If relied on, the main problem is you’ll have some bonsai that are over watered and others that are under watered, and that this will not be corrected by a system but be made worse. A few pro/con points:

  • Those of us who water everything the same—as automatic watering systems do—tend to have some bonsai that are weaker or stronger than they should be.
  • Younger plants that are NOT YET bonsai and are the same species, of the same age, in the same soil, and with the same the growth goals might be watered effectively with an automatic system.
  • They may prove useful for the busy lifestyles of the non-retired-
  • If you use an automatic system, check it constantly.
  • And try to use it only as an adjunct to hand watering.
  • And check for trees that are not doing well. They might not be getting water, or they might be getting too much. Those will require special care.

How to water bonsai is something I’ve shied away from speaking about much here, as it’s a learn-in-person kind of thing. Hoses and cans, with a skilled, thinking person operating them, will give the best results for bonsai.



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  1. Terry says:

    Thanks Michael, the timing of your article was spot on! I have been thinking about what I am going to do now regards watering since changing to more freely draining growing mediums. Your article gives some good insights. By the way I have a couple trees in pure perlite now, thanks to your suggestion. Am eager to see how they respond, will know more later in the season. Thanks again and looking forward to the next article 😉

  2. anijhuis says:

    Well I am guilty of relying on my automatic system – but I do hand water I make sure all trees get sufficient amounts . I am glad you did not post ‘ it takes 3 years to master the ART of watering’.
    Thanks for a logical post

  3. andre says:

    great post i’ve been lucky to never need a automatic watering system i’ve always used a copper can and you get to know your trees and inspect them at the same time watering my collection is one of the most relaxing aspects to bonsai for me watering right after sun up catches this feeling in the air that cant really be explained by words

  4. anijhuis says:

    Oh by the way the Bernard Dehydrated Water works well when mixed with Superthrive – amazing results

  5. endsurg says:

    I agree with your recommendation of not relying on an automatic watering system, however, unless a person has a job or life style that permits him or her to be home everyday to hand water, what is he or she to do. Most people go away for several weeks of vacation a year or conventions or business. I have found that relying on other people to water the trees while away is very dangerous, especially children. Neighbors are just as bad. For the most part, people who are not bonsai enthusiasts think of bonsai as outside house plants and treat them as such. I have had several friends lose trees because they’ve depended on other people to water while they are away. My theory is that the damage is not always seen immediately. Sometimes, sparse watering weakens the trees and the damage is not seen until several years later. On the other hand, the automatic watering systems are not fool proof. I have a personal anecdote to show Murphy’s law in action. I took my children on a week vacation and used an automatic system with a timer. I tested it for two weeks before to make sure nothing could go wrong. It worked flawlessly. I came back and the system was working but a friend who I asked to stop by each day just to make sure it was working told me that he stopped by to check and saw a neighbor turning the water off. The do-gooder said, “I noticed the water faucet was dripping, so I turned the water off. I didn’t want to waste water.” My friend put up a sign that said, “don’t turn off water no matter what.”

    I’m curious, if using fast draining soil, what difference would you recommend in watering style under which circumstances.


    • Dick says:

      I’d live to ad ons t hing to Paul’s remark. Several years ago I was away foto’s a short holliday and asked my son to water my trees for me. Two very hot days turned Two of my larches completely brown. My son was convinced hè killer my trees and felt terrible about in.
      Since then I never made someone else responsable for my trees animore and use an automatic wateringsystem, despite all the negative aspects.


      • crataegus says:

        Automatic systems can be very useful when gone on vacation. I’ve used them. Just be sure you’ve someone checking the system…

  6. bonsaibible says:

    I too have tried using an automatic watering system once when I was away on holidays and was actually pretty impressed with it, the bonsai wasn’t dying when I came back! haha

    But I agree with you in that they aren’t very useful when you have multiple species of bonsai as each needs different care and therefore different watering patterns.

  7. Chuck says:

    I use an automatic system and have for over 5 years almost exclusively. I own and maintain over 300 trees. I also rarely lose trees. Hand watering was just becoming a giant waste of time and there was nothing I was doing by hand that I have not been able to replicate with my auto system. As far as some plants needing more water or less water or mist or spray or whatever – thats the easiest part of auto systems. That is why there are dozens of options for heads for irrigation tubing. The same line can have a 10 minute run and some trees can get a half gallon of mist and some can get 3 gallons of fast dripper. To say all auto systems are bad or cant be used long term just shows ignorance in the types of irrigation that can be used. I can run over 36 different programs if I really want to so it is easy as can be. I rarely if ever hand water anything except for new transplants.

    • crataegus says:

      I disagree. But not with your particulars. You’re absolutely right that there are systems that can run any kind of program and amount of water and timing that you want. And I’m sure you could find a soil mix that will work with this, and a level of tree that will work with this. Heck, if you dislike watering and prefer to use that time elsewhere, there are watering systems that can help a lot. But there are some very good reasons that bonsai masters in Japan do not use watering systems, and spend enormous amounts of time in the summer watering by hand.

      I’m not ignorant of the systems available. You will still need to be constantly monitoring which plants need to be shifted to different timings and watering cycles. And it’s really hard to tell which trees are using water and which are not if you’re not watering by hand. A computer can’t think and adjust. You’ll still need to do that. And in truth a person takes a long enough time to learn how to water, but that’s sort of the fun of it and the education of it, too.

      Certainly watering can be seen as a waste of time, or the best thing we do with our trees. I love to water. And I love knowing intimately what’s going on and how much they’re using because that tells me a lot, and can really influence what my decisions are with the tree in terms of bonsai work.

      Weather is primary. Many parts of the country have vastly differing patterns every week. And, there are some watering systems that are out there that can change their watering according to the weather, and for some applications that is good enough. And yet that is not good enough for the kind of pinpoint watering I like on the developed old trees I have. A defoliated tree or a pine growing new candles in June changes by the week how much water it needs. Sure, you can pick it up and move it around to another system, or change the cycle, but if you can figure that out you’re doing very well. But it’s just another form of busyness like watering by hand is.

      Some plants really shift their water needs very fast according to technique applied or time of year, and those can very quickly translate into growth and root changes. And one tree might be very different than the one sitting next to it.

      If we’re talking about trees without a lot of development, then we’re really talking about apples and oranges and I can’t find fault with anything you’ve said. But if you’re talking about applying modern bonsai techniques to a whole range of species, ages, levels of development, training goals, health, then no, I prefer hand watering.

      So, although there are benefits to watering systems—which I think I allowed for in this post—they are not going to give you the benefits that hand watering will do. I’m willing to put in the time to get the benefits of hand watering.

      We could get dog walker programs or something of that nature, but maybe we’d miss the early signs that our dog is ailing that we’d catch if it looked a bit winded after the first turn around the block. Same with automatic watering systems.

      Thanks for the comment-

      • endsurg says:

        I agree, Mike, watering is really a misnomer. I try to explain to people that watering is not just getting the soil wet. It is a process that pushes the waste products out and permits oxygenation of the soil. I sometimes think of it as “massaging the roots”. Plus, while I’m watering each tree, it gives me a chance to pick out all of the weeds that are constantly taking root, pull off dead leaves and branches, look for bugs and really look at the tree: is it healthy all over or are there some spots that don’t look so good. I love watering. For me its one of the most peaceful times of the day. I only use an automatic waterer when I absolutely can’t be there. Then, they are invaluable. I believe that it is impossible to overwater trees in a weeks time so that root rot occurs. If it does occur, I think the soil is not draining fast enough. I think if watering is thought of as a burden, a person might consider reducing the number of trees they have.

  8. I lost a bunch of trees once because my well meaning neighbor heard the water was going in my back yard and shut off the water to my place because he knew I was gone and was afraid it might be damaging something. I had a pipe burst in my home and flood inside my house a few months prior and had complained about that to him. UGH!

  9. Mike says:

    I have to agree with everything Michael says. I use an automated system only when I have to, and I fret some every time I’m forced to rely on it. I have about 35 trees, about 1/3 of which are pre-bonsai. I inspect them all before departing on my trip and assess what kind of watering each requires. I group the like ones together. Most, if not all of the pre-bonsai can get the regular sprinkler that waters my yard. The bonsai will get the drip and/or mister, with the flow adjusted to what seems right. Despite all that, I do worry, since, as Michael mentions, there are variables like weather that impact watering, and the possibility of mechanical failure. Living in Florida, the water demands can vary greatly from day to day. A warm, windy day with relatively low humidity will have all my trees needing water. The next day may be raining, or just very high humidity, and many trees will still be moist from the previous day, so I hold off on watering those. There is no way that my automatic system can know or adjust to that. I also agree that you learn so much from looking at your trees every day. If a tree is staying unusually damp, then it may be telling you it has root issues or some other kind of problem. If I had 300 trees, then certainly I couldn’t afford to devote this kind of attention to every tree, and I’d have to rely more on mass watering, whether by hose or automated. But then I’d have other problems with 300 trees as my wife would kill me since I do this just as a hobby and not a business. A final note, I’ve seen a good amount of discussion on using very fast draining bonsai soil…essentially no organic material at all. Walter Pall claims it is virtually impossible to overwater, though it does require frequent fertilizing. It would certainly simplify watering in general, especially if using an automatic system. It still wouldn’t take the place of daily inspections though.

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