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.