With the resent water restrictions that we have in the Stellenbosch, my home town in South Africa. We may use 100 liters of water per day per person on the property and you are not allowed to use the municipal water for watering plants or use it outside the house. I thought it would be a good idea to share the techniques I use to water my bonsai trees. I have used various techniques the past few months to try and save water but keep my trees in a healthy condition.
I installed a sprinkler system a few years ago to help water my trees. I had less trees and water restrictions was not in place. I used micro sprinkler heads. I had sprinklers that covered 360 degrees in a 1,2m radius and heads that covered 90 degrees for the trees in the corners. I placed the heads against the roof to cover more trees without any obstructions. In the summer this system worked 100%. As I watered my trees twice a day for 30 minutes. Once in the morning and once during lunch. Problems I had if I did not use the system for 30 minutes twice per day some of the trees didn’t get watered properly. When the wind blew, the side the wind come from was dry. Trees with big canopies did not get watered properly and I always had to water them again after I used the sprinkler system. This system wasted a lot of water as it did not only water the trees it also watered the entire area around the trees. If I had to set up a system like this again in the future I would get more sprinklers and set up my watering area in sections and set the floor at an angle so that I could reuse the water that runs off after I watered the trees. I’m not saying that this is a bad way of watering just keep in mind that rather cover a smaller area with more sprinklers and try to direct your sprinkler heads so that the pots gets watered evenly.
In the middle of last year there was a request sent out to home owners to cut down on water usage. I felt bad because I knew I was using a lot of water. I then decided to use I gardening hose with an adjustable spray nozzle. I cut down on my water usage by almost half. The negative side to this was that I need to water each tree by hand and it took me close to 25 minutes to water all my trees. This may not sound like a lot of time but previously I opened the tap and continued with my morning routine and I did not have to be present during the watering. Now I had to wake up earlier and spend an additional 25 minutes with my trees in the morning. The up side was I could see every tree and could see pests earlier. Whit this I also found that trees needed less water as they were water more thoroughly each time they were watered. This method of watering was great, the one down side was setting the pressure right every morning before you start watering. If the water pressure was to high, you washed out your top soil and moss. If the pressure was too low, you would be watering longer as the pots will take a while to fill.
I cut back on my water usage and I was comfortable with the amount of water I was using. Once more a request was sent out to home owners at the beginning of this year to cut back on water usage even more. By now it felt like there were no more ways of cutting back on water usage. I spent a few nights wondering about this and I came up with watering with a watering can. I would fill a bucket (25 liters) with water and use this to fill the watering can. I came to the realization that I use about 75 liters to 100 liters of water a day on watering my trees. I was shocked as I never previously realized the amount of water I used. The next step was to use less municipal water. Like many other people I know I asked Google. The thing that popped up the most was rainwater harvesting. I got a quote on a rainwater harvesting system with all the bells and whistles. I nearly had a heart attack when I got the quote. As the demand for water harvesting went up well so did the costs. I could not afford this. That was a great excise. I then went back to the drawing board. I cut all my down pipes that where link to the gutter at a level just high enough for me to fit a 25-liter bucket underneath it. That’s how I started. I now have enough buckets, bottles and bowls to store about a 3-week supply of water. This past few months I have managed to use 0 liters of municipal water to water my trees. I now spend 1 hour on watering my trees.
If I some how get the money to buy the rainwater harvest system I was quoted on I will add the pressure pump with a demand valve to the system. This is something to invest in.
Submerging a tree in water
This is another way of watering. I find it very helpful for trees with well-developed root systems. Why is this you may ask? If you water your tree with a water can or whichever other way you do by pouring water on the soil. The water has difficulty penetrating the dense root ball. What happens then is that only the outside roots get watered and the center of the root ball is bone dry. What I do is fill a large bowl with water and submerge the tree with the pot into the water till the entire pot is covered with water. As you do this you will see bubbles in the water. Keep the tree in the water till you see that there are not more bubbles coming up from the pot. Take the tree out of the water and allow the excess water to run off.
The above-mentioned watering techniques works great with trees in pots. There are however a few of my trees that are planted on slabs or some of my accent plants that are planted on rocks and small stones. With these I use a pressurized sprayer on a mist setting to water them. This does not disturb the moss or landscaped soil.
Here is a photo showing the items I use to water my plants.
Then cutting down on my water usage I also started looking at ways to keep the soil moist for longer. The first thing I changed was my soil mixture. Trees are now planted in a slightly more water retaining mixture. Some of the trees do not like standing in wet soil for too long. For these trees, I looked at humidity trays.
To keep the soil moist but not wet was a difficult thing to get right as I could not always come home during lunch to water my trees. I then had a look at humidity trays. It is a tray that is placed under the tree that hold water or at least that is what mine looks like. The trick here is not for your tree to stand in the water but to keep the environment humid. What I did was fill the trays with stones. I then placed the tree in the pot on the stones. This then helps to keep the tree cool. A tree loses more water through the leaves in warm and dry conditions.
Here are a few photos of my humidity trays.
These are techniques that I used. Please do not feel bound to these techniques. The best watering technique for you is the one that works well in your environment and fits into your daily routine.