by George Buehler

EDITOR'S NOTE: This article describes an irrigation system using materials I obtained from DripWorks – a California irrigation company. There are other companies that also supply such equipment. The Greater Louisville Bonsai Society does not have an affiliation with DripWorks and does not recommend use of their or any other supplier of such equipment.

In my professional life, I was away from home on business a lot. This, of course, put a large load of tasks on my wife. She dutifully watered my bonsai on a daily basis, but I hoped to find something that would relieve her of this duty. When I decided to set up an automatic watering system I had the following requirements:

1. It has to be flexible since my tree layout would change yearly.
2. It has to be easy to modify.
3. It has to be relatively cheap.
4. The parts have to be rugged and able to last a number of years.
5. It has to be reliable and operate relatively flawlessly.
6. It has to water the whole pot, with no dry spots.

I was looking through a Bonsai Today and I noticed an ad for Dripworks – advertised as an irrigation system for bonsai. Hoping that this was the solution, I requested a catalog from them. While I was waiting for the catalog, I went to the net and found an article by Brent Walston of Evergreen Gardenworks on automatic drip mist systems for bonsai. He stated that the advantages of automatic drip mist watering bonsai are convenience, reliability, adequate and timely watering, and ease of in-line fertilization. He also stated that the disadvantage was that you don't get to see your bonsai everyday to spot problems, unless you have some other routine for visiting every plant every day. I thought that the convenience for my wife would outweigh the disadvantages (unless there were some that Brent didn't mention in his article).

I have spent the last five years (and a large number of dollars – but more on that later) working on developing the 'ideal' bonsai watering system. After five summers of evaluating a number of different configurations and set ups, I still haven't 'settled' on a system, but have found a system that works – with some restrictions.

I must say up front that an automatic system of any type is not for everybody. If you have two or three trees, using a watering can will be your cheapest method. If you have a large number of trees or are away from home often, you may want to consider setting up an automatic system. Of course you may enlist the aide of one of the other members (or a neighbor) when you are out of town to do the daily watering. Using other members who understand the importance of watering bonsai is ideal. Use of a neighbor would require a lot of education and could strain the neighborly relations you may enjoy with them.

INITIAL SYSTEM SET UP

How complicated you make your system depends on a number of factors such as the number of trees you need to water, the locations of the various trees, the type of trees and their pot size. I will give some general guidelines later.

When I got the Dripworks catalog, I had more questions than answers because their catalog has a super large variety of parts and supplies. On one page, they do list some of the things you should consider when getting ready to order from them and some parts to order that you will need when you do order - this was very helpful. The information on this page is better suited to general landscape watering than it is to bonsai; however, it did help. When I called them to place an order, the person answering the phone was extremely knowledgeable in general irrigation, but had limited knowledge when it came to watering bonsai. With some discussion on what I needed, she made some recommendations that seemed reasonable.

The first thing you need to understand is that these systems use plastic spray heads that are extremely small and can plug easily. Because of that, you will need an in line filter for your city water to remove any particles in the water (yes, the Louisville city water does have particulates of several types in it). The one I use has a 200 mesh stainless filter size. These filters come in 50 to 200 mesh filter sizes. The larger the number the smaller the screen size and the quicker the mesh can plug. I recommend a filter that can be flushed routinely during the use periods – which is what I purchased. So far, I have had no trouble with filter plugging. However, I try to remember to flush the filter once or twice a season but don't do it on a regular basis. Price ranges from $10 to $27 for home quality. Mine cost $17 and should last many years.

Typically municipal water systems have a head pressure of 60 to 100 psi. Since the parts are plastic, you will need a pressure regulator to reduce the city water pressure to the 10-30 psi range. If this pressure wasn't reduced, the plastic parts would probably burst; and even if they didn't, all you would get out of a spray head would be a fog. Price for these regulators ranges from $9 to $20. Based on the recommendations of the ordertaker at DripWorks, I settled on a 30 psi unit.

My water is obtained from a house water spigot (PICTURE ONE). Notice that I have a 'Y' splitter on the spigot so that I can get water without disconnecting the irrigation system. Also notice that the 'Y' splitter has a valve on each side. This allows the spigot to be open all the time to feed the irrigation system and still be able to turn off the hose on the other side. PICTURE ONE also shows the water filter and the pressure regulator

To get the city water to your trees, you will need a combination of 1/2" mainline tubing ($11/100 foot) and 1/4" tubing ($5.50/100 foot) along with fittings to distribute the water (all relatively cheap). Depending on the spray head you use, you may also need some 1/8" tubing ($4.30/100 foot) and some fittings for this size. One word of caution: just because the tubing is listed as 1/4" doesn't mean that it really is 1/4". The size of tubing from one manufacturer may be different from another. So if you find one source, try to stick with it; or, if you change suppliers, ask for a sample before you purchase a large amount, to make sure it is compatible with the rest of your system.

If you are going to set up such a system, you will want the system to come on automatically and will, therefore, need a timer. This is where you will have to use a lot of restraint. Prices and options for timers run the full spectrum from simple/cheap to complex/expensive. I didn't want to go to the trouble of setting up a 110 volt electrical line, so I chose a battery-operated timer. It is not as versatile as some of the AC timers, but is more than adequate for watering bonsai. It can be set to turn-on each day for up to four times a day. Each turn on time can be from as little as one minute to as much as 6 hours. It would be nice to be able to water at different times for different lengths of time on different days, but I didn't investigate this since I was sure the price would be higher than the simple one I purchased. My timer hasn't failed to operate since I set it up. It cost $50.00 (This was the most expensive part of the system). At the start of the watering season, I put two new 9 volt batteries in it. These last very adequately for the entire watering season.

I really debated as to which type to get since Mr. Walston, in his article, stated that battery operated timers were too erratic for him to use. Electric timers range in price from $60 to $250 just for the timer, and then you would have to purchase separate electric valves (for the main line water supply) which range in price from $20 to $60. Since I didn't know whether this type system would work for my bonsai, I definitely didn't want to spend this type of money. I must say my two timers operate exactly as advertised and there has been no problems with it being erratic. However, if for some reason I had to start over with my system, I probably would investigate an electric timer to have more versatility.

SPRAY HEADS

I tried a number of spray heads since I started this project. Each has advantages and disadvantages. I find that a particular type of spray head may be perfectly suited for one type or size of tree but not at all suited for another type. In general, of all the spray heads, the mini mister (PICTURE TWO) is probably the most versatile. It can be placed where it is needed, moved easily, and gives out adequate water. The problem with this type head is that if the trunk is large, only one side of the pot is watered and may require a second head. For small trees or shohin, it works very well.

When the trunk is large or the pot is large, the drip hose (PICTURE THREE) is a great find. I recently started trials on this tubing (made from recycled tires) and find it works very well. I control my water pressure at 30 psi; and at this pressure, the drip hose sometimes sprays water rather than drip, which doesn't seem to be a problem in getting the soil completely wet. The big advantage is that it can be wrapped around the trunk and spread out over the pot to get a good distribution of water to all parts of the pot. It is a little unsightly, but it distributes water well and does its job. I find that when using two turns around the trunk, the bonsai soil gets adequately wet. Two things need to be explained in regard to picture three. The first is the tubing that shows up white in the picture. This is Tygon® tubing that I use over the wire securing the tree to keep from scarring the roots. The second is that the black drip hose should be better spaced over the soil than what shows up in Picture Three. I had to do some manipulation of the pot to get a decent picture, and the hose apparently shifted from where I had placed it.

For forests there are several options – once again each has advantages and disadvantages. The flat sprayer (PICTURE FOUR) sprays water in an almost flat pattern over an area of about 45 degrees. The octopus sprayer (PICTURE FIVE) sprays water in a 180 degree circle but takes longer to wet the soil. Depending on the soil structure, this head may leave dry spots. I would rank this head as acceptable, but on the low end. If you use an oval pot, the flat sprayer would be better. If you want to put out a lot of water in a forest (or for other applications), the tornado head (PICTURE SIX) is the best choice. It can be adjusted to cover a large area, or to water several trees or pots at the same time.

A newer head, the mister (not to be confused with the mini mister – PICTURE SEVEN), puts out a fine mist. This can be used for cooling pots/trees, wetting down foliage, or just general watering. When the mister head is straight up as in PICTURE SEVEN, a rather large area can be covered with a very fine mist. As the valve is opened to full, a finer mist is generated and the greater the cooling effect or the wetting area.

Some of the spray heads come with a built in valve (as in PICTURE SEVEN). However, as a normal rule, I still put a valve before the head, or drip hose for several reasons. It acts as an emergency backup, and it enables me to have a finer control over the flow of water. By adjusting the valve before the spray head, you can water daily but not soak the plants that don't require as much water (i.e. Pines).

Spray heads cost $0.20 to $0.90 each, and the valves cost $0.60 each.

WHAT DIDN'T WORK FOR ME

I tried a number of things that didn't work for me. Luckily none resulted in any major disasters because I would try it when I knew I would be home to observe the results. As mentioned elsewhere, some things work for one type of tree/ pot arrangement, while not working for others. However, there were a few things that didn't work for any tree setup.

One type of hose that is called a soaker drip line didn't work. I obtained a hose that contained an emitter spaced at 6" intervals. If this hose was used around a plant in the landscape it probably would work fine. But for bonsai, it left dry spots, no matter how many coils I wound around the trunk.

Other types of heads that were designed to give a specific spray pattern, such as a strip or half circle also didn't work in my bonsai setup. There must be a dozen different types of these spray heads. I couldn't get them to thoroughly water the pot and would end up with a lot of water outside the pot or dry spots in the pots. When I got this result, I would abandon that particular type of head.

Something I didn't try was an oscillating sprinkler head like those used in a lawn watering system, only on a much smaller basis. This type of head may work for some setups but would use an excessive amount of water in my situation.

COST OF SYSTEM

How much did this whole system cost? As previously stated, the timer is the most expensive element. To water about 40 bonsai pots and/or nursery containers using an automatic system should cost you about $100 to $150. Of course if you have less trees to water, the system will cost somewhat less, but not truly proportionally. This investment should last you at least 5 years. At the end of the growing season, I take apart the whole system and store it in the basement. If you don't experiment with different setups, this should be the total investment. You may have to buy additional parts to replace broken or damaged items; but, if you use caution, the various parts should last a number of seasons.

Because I tried a number of different heads (a number not documented here) and different setups, my cost was substantially higher than the above (an additional $100 - 150). I would see a different or new head and purchase at least 5 of them. My reasoning was that in order to get a good representation of the effect of the new head, I had to try several on different tree designs. Of course, trying new spray heads means using additional tubing, fittings, etc. and additional costs.

GUIDELINES

• Start with a battery operated timer to keep cost lower.
• Use pressure regulator at either 20 or 30 psi. Probably 20 psi would work well.
• Make a layout plan of your bonsai stands and the type of trees on them to get a rough idea of the amount of tubing needed and the number of spray heads needed. Add several extra spray heads of each type for backup.
• For forests use a spray head that puts out uniform spray pattern. A good choice would be one like the one in PICTURE SIX.
• For large trunked trees or for trees planted in large pot, use a soaker hose that delivers water over entire length of hose.
• For smaller trees or pots use a misting head like the one shown in PICTURE TWO.

ADVANTAGES

• Once set up, it gives uniform watering in a short time.
• It saves time when watering a large number of trees.
• It can be away from your trees and still have the trees watered in the same manner.
• It can be set up for automatic fertilization.

DISADVANTAGES

• It waters daily whether it needs it or not. This can be overcome by using a rain sensor.
• It may water some plants more than they need (i.e. pines) without adequate testing.
• You can't see tree problems unless you set up another routine to look for problems (i.e. insects, etc.).
• If the timers don't work properly, trees can suffer irreparable damage.
• There is may be more wasted water using this method than using a hand watering system.

PRECAUTIONS YOU SHOULD TAKE

If you set up an automatic watering system, there are a number of precautions that must be observed:

• Although I have never had a timer failure, there is always the possibility of failure. Therefore, if you leave your trees, it is always recommended to have somebody knowledgeable in bonsai visit your trees to make sure the system has worked.
• Instruct your tree watcher as to what the watering system should look like when it operates, what time it comes on, and how it should work so that they know what to expect when they come over.
• Have your system set up at least 3 to 4 weeks before you plan on leaving so that 'you' know how the system works and can correct any problems before you rely on it to water your trees.
• Plan on purchasing several different types of spray heads the first year and determine which works best for your trees. Use the information in the spray head section above which may save you some time and money.
• Even if you are with your bonsai every day, don't depend completely on any automatic watering system. When the temperature is 95 degrees, a day without water can be disastrous.
• Birds like to perch on the small tubing and can easily dislodge the spray head so that a particular plant is not getting any water. Securing the various hoses helps alleviate the problem but doesn't eliminate it.

FUTURE ACTIONS

Some of the things I plan on doing/trying in the future:

Use of the mini sprinkling head

Use of an in line fertilizing system

Use of rain sensors which keeps the system from coming on when a certain amount of rain has occurred

Develop a better method of securing the various heads (or hose) to the pots so that strong winds and birds can't dislodge the heads from the pot

Investigate the use of an electric timer to allow setting up various zones and different times of on/off timing

CONCLUSIONS

With proper forethought and planning, an automatic watering system can relieve you of some of your bonsai duties. It can be used for daily watering, misting new cuttings, or simply cooling pots on extremely hot days.

My automatic system has worked for me and has allowed me to be away from my trees with the knowledge that the trees will be watered as they should be. Of course I still take precautions, but at least I have some assurances that the trees will be watered. As usual, I must restate that this type system works for me but may not work for you.