It sure doesn't look hard but watering bonsai can be challenging. There is a lot written on it and this is more of the same (but hopefully a little different).
I thought I would talk about how I water because this is the sort of subject that I had a lot of questions about when I started and I never found anything written about it from a Calgary-grower's perspective. I would encourage anyone with different methods to please post them and criticize my methods should they have reason to, because the way I water is by no means "the way," but a way I do it, and I'm always looking for better methods. That's enough preamble I think...
Like most bonsai-folk there are two main rules I follow when watering bonsai:
Water only when necessary and Water thoroughly.
Watering only when necessary
If you water too often you can cause root rot and your tree will quickly go down hill. Supposing that you have your trees in modern, loose aggregate bonsai-soil, if it's the middle of Summer (like at the time of this post) and your soil is still wet three days after watering, chances are pretty good that your tree's roots have stopped working and have begun to rot. You of course want to avoid this as best you can but not at the expense of the health of the tree.
More often than not new bonsai owners tend to under-water and with the granular soil aggregates in use today it is very difficult to over-water. On the other hand, under-watering is particularly easy to do in Calgary; our altitude and high winds can quickly dry out shallow pots, and even more quickly dry out leaves. While soil must be allowed to dry (different trees having different preferences of dryness) the leaves must have sufficient humidity to remain turgid, to insure heavy budding and short internodes. To deal with this I have taken to misting my trees at least once a day (two-to-three times a day during the hot Summer days).
If you have a lot of plants in your yard, or have your trees near a pond or fountain, you likely have enough localized humidity that you won't need to mist your trees as often as I do, but for my efforts I have noticed considerable improvement in the health of my trees in my arid and windy downtown apartment location. Though different types of tree will have different needs remember that the humidity requirements of a tree in a pot will always be slightly higher than the same tree in the ground. What is crucial is to create the proper relative humidity for your bonsai and this can best be determined through study and experimentation.
So with the above considered... How do we know when to water?
For this I use what's commonly called "The Chop-Stick Method." (I believe Michael Persiano popularized this method).
The Chop-Stick Method is pretty much what you think:
- Take a *chopstick (I like kabob/sate skewers because they're smaller) and push it into the soil a few inches (to the bottom if it's a shallow pot).
- Wait 5 minutes.
- Pull out the stick and test it against your skin.
- If it's dry or nearly dry, you need to water; otherwise don't.
*You can also use your finger, but I find that the finger is easier to trick than the stick (the finger sometime senses 'cool' as 'wet').
There are other methods of course: some people can tell by weight of the pot; some can do it by the appearance of the tree or the soil. To be honest I'm not that in touch with my trees yet so I use a stick. Whatever you use make sure that you are waiting until the tree needs water.
Watering thoroughly
I use Herb Gustafson's method for watering. It involves three stages:
The first stage helps make the dry soil more receptive to water.
- Gently apply water to the surface until covered and allow to soak in. Try to use an ultra-fine upward facing rose head on your watering can/wand. The rationale behind this is that the finer water stream is less likely to disturb the surface soil. This is important horticulturally and not just cosmetic; it's important to maintain a settled layer of top soil to help with the development of fine feeder roots and to aid thickening of the large surface roots (deeper roots = thicker roots, don't expose your nebari until they're ready). If you accidentally wash some of the surface soil away make sure to replace it.
- Water the surface again until it begins to drain out the bottom.
- Wait 5 minutes...Dry soils are not unlike dry sponges in that they repel liquid until their surface softens and expands. This 5 minute break allows for the accretion of water in the interstitial spaces between grains of soil and thereby "softens" the soil structure making it more receptive. This trapped water will in turn attract and retain by means of surface tension the water we add in stage two.
The second stage saturates the soil.
- Water as before.
- Wait 20 minutes (at least...30-50 minutes is better)... This time gives the roots an opportunity to take their fill.
The third stage provides a cleansing rinse.
- Water again. It should drain continuously at this point (depending on the soil and level of root colonization). I usually give it about 10-15 seconds of steady and gentle watering and then let it drain. If I am feeding that day, I forgo this third stage of watering and instead apply liquid fertilizer.
Watering complete.
Some people think Gustafson's watering method overdoes it with the final "rinse" stage. If you only feed your trees once or twice a month, or if you use a very loamy/mossy soil, then I would agree that this method has one step too many but if you feed your trees quite heavily on a weekly basis then I think it is very important to flush soil out thoroughly.
Calgary has notoriously hard-water but this can be a blessing instead of a curse if you feed your trees aggressively. Most of my trees are still in development and benefit greatly from a heavy feeding schedule. High fertilization regimens tend to bring the pH down (more acidic) but by thoroughly rinsing with Calgary's high pH water you help to balance this acidity while at the same time preventing build up in excess nitrogen and thereby avoid over-fertilizing. When I am not feeding, or feeding less, during the Fall, Winter and early Spring, I adjust this method and only complete stages one and two so as to avoid leeching the soil of nutrients. During this time I tend to only complete the rinse two to four times a month.
That's it. That's all.
Please tell me what you think and share your own techniques.
Thanks for reading,
Jeremy
