By Brent McGhie, UC Master Gardener of Butte County, May 19, 2017.
The most important advantage to drip irrigation is that it is more efficient than traditional irrigation methods. Drip emitters can be placed to deliver water only where it is needed, so water isn't wasted on unplanted areas. By applying water slowly, drip irrigation also allows water to be absorbed quickly into the soil instead of standing on the soil surface. This means that far less water is lost to evaporation than with flood irrigation or sprinklers. Additionally, because water sinks into the soil rather than puddling, there is less loss due to runoff, which makes drip irrigation a good choice for steep terrain. Another way in which drip systems can conserve water is by installing them under a layer of mulch, promoting even greater water savings by further reducing evaporation from the soil. Last but not least, it should be noted that by saving water, drip irrigation also saves the homeowner money.
Drip irrigation has several other advantages. In addition to water, plant roots also need air and when soil pores are completely flooded, roots can actually “suffocate.” The slow application of water by drip systems virtually guarantees a good soil/water environment with a balance of water and oxygen in the soil. Next, weeds don't grow if they don't have water, so they become far less of a problem when water is efficiently targeted to desirable plants by using drip irrigation. As a bonus, this means that herbicide use can be cut back or eliminated, which is better for both the environment and the pocketbook. A final advantage of drip irrigation is its flexibility. It can be installed in a variety of landscapes and, at a relatively low cost, it can be altered and changed as plants grow.
There are disadvantages to drip irrigation systems that should be considered as well. Sediment or bugs that find their way into the tubing can clog drip emitters. In-line filters can be installed to eliminate most of this clogging, but mineral deposits can also clog emitters. There is really no easy way for homeowners to eliminate this, but clogging due to mineral deposits can be delayed by using emitters with a greater flow rate. For example use a 2-gallon per hour (2gph) emitter rather than a 0.5gph emitter, but run it for a shorter time. The faster flow discourages mineral buildup which can cause clogging.
In addition to problems with clogging, drip irrigation systems, with their softer tubing and plastic emitters, are more easily damaged by animals than irrigation systems made of sturdier PVC or metal components. Some dogs seem to delight in chewing on drip tubing, and drip systems also make tempting targets for thirsty rabbits or squirrels. On the plus side, burying drip tubes in shallow trenches or under mulch seems to be effective in mitigating this sort of damage.
If you are considering installing a drip system, putting it on an automatic timer is recommended. An automatic timer provides a consistent watering schedule. With a timer, you provide the exact amount of water you want and there is no forgetting to turn the system on or off.
Something else to consider when planning a drip system is planting zones. Simply put, this means that the same valve should service plants with similar watering needs. You wouldn't want a drip line that waters a vegetable garden to also serve a cactus garden, because their water needs are so different. A simple, inexpensive pressure regulator is also necessary because drip systems require far less water pressure than normal house pressure. Most emitters cannot withstand pressures greater than 40psi and micro-sprinklers cannot function below 10psi (psi stands for “pounds per square inch,” the measurement standard for water pressure).
Many retailers offer how-to pamphlets that provide further information on drip irrigation components and installation.
Schwankl, Larry, and Terry Prichard. Drip Irrigation in the Home Landscape. Oakland, CA: U of California, Division of Agriculture and Natural Resources, Communications Services—Publications, 1999.
By Mahina Gannet and Jeanette Alosi, Butte County Master Gardeners, May 31, 2013
If you plan to travel this summer, now might be a good time to install an automatic watering system. Doing so can ensure that your plants will not be under-watered or over-watered in your absence.
An effective irrigation system will supply the right amount of water to each plant resulting in water savings and more healthy plants. It will reduce weeds and help prevent pest and disease problems from occurring.
Drip irrigation is the tool that can help you minimize water wastage and maximize water’s benefits to your garden. Drip watering is the frequent, slow application of water to soil through emitters or micro-sprinklers. Drip irrigation works well for vegetable gardens, ornamental and fruit trees, shrubs, vines, and outdoor container plants. Even without an automatic sprinkler system installed, a drip system can be set up using a standard garden hose attached to the main drip line.
Installation of a basic, simple drip system is quite straightforward, and easily within the grasp of most home gardeners. It goes together much like a tubular erector set, all snapping together. Main one-half-inch (1/2”) or five-eighths inch (5/8”) polyethylene tubing line connects to your water source (if you’re on well water, you need a filter on the water source). Drip emitters, microsprinklers, or ¼” spaghetti tubing with emitters can be installed off the main line using barbed connector fittings that poke into the main lines. Solid spaghetti tubing can also be attached to the main line with an emitter attached at the other end to provide water directly to the plant. Alternatively, main line poly tubing can be purchased with in-line emitters pre-installed inside the tubing. Both the main poly tubing line or the in-line emitter tubing can be snaked through your beds or circled around shrubs and trees to deliver water directly to your plants.
With a drip irrigation system in place, water will be delivered a) directly to the plants of your choice and b) directly to the roots of those plants. These two simple factors can lead to fewer unwanted weeds in the garden and help reduce plant diseases.
The second consideration for smart watering is consistency. An automatic watering system is extremely consistent because it runs on a set schedule.
The timing and amount of water you deliver depends on the plants to be watered and the soil type. Depending upon your soil’s density, water will move quickly or slowly through it. For example, water poured through sand will move very quickly because sand is loose rather than dense or compact. But water poured through clay will trickle very slowly. Consider the plant’s whole root structure within your particular type of soil. An effective water system will deliver water to the entire root structure. The goal is to water for deep, strong roots that that aren’t waterlogged.
This is where math becomes useful. Drip irrigation emitters release a certain amount of water per hour. You can calculate how much water you are delivering by employing simple multiplication and division; with that number, you can decide how long you need to run your irrigation. Decide on the amount of water required by the plants each watering cycle, calculate the amount of time needed to deliver that amount (gallons per hour per emitter x total number of hours = total gallons per emitter) and water for that amount of time.
Watering is an active relationship that requires constant adjustments. You may need to tinker with your system to make seasonal changes, fix broken pieces, and make adjustments for better efficiency.
While drip irrigation is a good way to achieve efficient watering, it is not absolutely necessary. What is necessary is analyzing your own plants and determining how to best meet their needs given your personal situation. If you are a gardener who travels frequently, implementing a reliable automatic watering system will reassure you that your plants will remain happy, well watered, and growing until you return.
A very helpful publication on this subject is the University of California Agriculture and Natural Resources (UC ANR) Publication 21579, “Drip Irrigation in the Home Landscape.”