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.”