A Brief Introduction to Drip Irrigation

Drip irrigation will solve every problem that you’ve ever had or will ever have in your garden. Ok, perhaps that’s an overstatement, but the relatively new technology makes it easy an inexpensive to install an irrigation system that is perfect for the home garden. Drip irrigation is an above-ground system that uses non-toxic polyethene tubing. You can check them out here: http://www.dripirrigation.com/.

It is a very flexible sytems (literally and figuratively) and are very affordable. For instance, I designed a system for a 2600 sq ft garden at the Roxbury YMCA that will cost about $300 for materials. I bet your garden is much smaller than that and could benefit from the many advantages that drip irrigation offers. The base price for the faucet fittings and timer costs around $60. After that, the lines cost as little as $60 per 500 linear feet, which can cover 5000+ square feet of garden. Accessories can ad up a little bit, depending on how complicated the system is (number of zones, joints, etc.)

The Benefits

A customizable and precise watering-the system: The system is calibrated to deliver as much as your plants need and can be divided into two or more zones in the garden. Watering too much or too little is one of the top killers and causes of disorders and diseases in plants. One word of caution: if your site is excessively hot and prone to evaporation

Water savings and erosion prevention: Drip emitters deliver water very slowly, allowing it to seep into the ground and allowing plants to take up as much as 70 percent of the water and eliminating waste from runoff and evaporation if you cover the lines with mulch. Watering with a hose or overhead irrigation usually delivers water too quickly and carries away particles of soil as it runs off.

Time savings: If you are gardener who can never spend enough time in the garden, this system is for you. I always recommend including a timer that will automatically shut off after a specified period of time. For a little extra dough, you can even fully automate the system by installing moisture sensors that tell the timer when it’s time to water.

Deep watering: This a very difficult thing to do well as a gardener. Spraying your vegetable patch for 10 minutes with the hose will not do it. Slow watering over a long period of time (we’re talking hours, not minutes) allows the water to seep deep into the soil. Therefore, new plants establish deep, drought-resistant root systems that allow you to reduce irrigation over time.

Disease prevention: Watering with a traditional sprinkler or hose wets the leaves. Repeated wetting of foliage creates an environment that is conducive to fungal and bacterial growth, especially if you water frequently. Drip irrigation avoids wetting the leaves and puts the water precisely where the plant needs it. Remember last summer when late blight ate up all of the tomatoes that you looked forward to all summer? The blight was brought on in part by the frequent and voluminous rains that we received all summer. Traditional irrigation often makes landscapes extremely vulnerable to infections and disease. Installing a drip irrigation system is preventative-medicine for your plants and will save you money over time.

Durability and reliability: Soaker hoses get clogged more easily and do not deliver an even amount of watering over their length. Drip irrigation lines water evenly and last for at least 10 years if they are properly maintained. Plus, you can easily replace components that wear out or get damaged without having to replace the entire system.

Designing: Here’s where it gets a bit dense…

Designing a system requires a little bit of knowledge about how water behaves in soils. Capillary action moves water laterally and upward through soil horizons. The more organic matter in the soil, the further water will spread from a drip emitter. The best irrigation systems slowly emit water (.5 – 1GPH per emitter is generally recommended) and are allowed to run for as long as it takes to soak through the entire potential feeding zone of your plants. Testing the soil and making observations about its consistency allows you to distribute the lines and choose the correct spacing for drip emitters in the irrigation system.

You also need to figure out the rate of flow from your outdoor spigot. A drip irrigation system will not begin to emit water until it reaches a certain pressure. This way, the entire garden (or zone) can be watered evenly. The lines work within a range of pressures, but will not reach their capacity of flow unless your spigot can provide an adequate rate of flow to reach optimum pressure.

There are a few ways to divide the irrigation system into zones. This allows you to customize the amount of water delivered to the zones according to plant needs. Watering needs are affected by the amount of light or shade, differences in grade, the cardinal orientation of a slope, differences in soil texture and the types of plants. You can install T connections and connect smart timers to control each zone separately. If you want to save a little money, you can swap the smart timers for a simple manual valve that shuts off part of the system. You can also choose lines with different rates of flow or different spacing between emitters, which will deliver a different amount of water during a timed irrigation.

Installation

Drip irrigation is installed by hand and only requires the right components and a tubing cutter. You start by attaching the necessary components in the head assembly to your outdoor spigot. Then, attach the lines and stabilize them with landscape staples or plastic pins. Cover the lines with mulch to conceal them and conserve water.

Once the system is installed, take it for a test run. See if there are any places where water is running off or any dry spots in the soil. You can use a tensiometer or soil-moisture gauge to see when the soil reaches the proper moisture content. You need to make sure to test at a depth of 8 inches for a vegetable garden or 18 inches for trees and shrubs in order to determine whether the system is reaching the entire zone where the plants do most of their feeding.

Operation and maintenance

The irrigation system itself should last 10+ years if properly maintained. Lines can be left out in the garden over winter if they are properly winterized at the end of the season. Filters should be cleaned ahead of every season and the head assembly should be checked to make sure that it is working properly.

You’ve sold me…So now what?

Ready to tackle an installation yourself now? Here’s a more detailed tutorial OR, for all of you who are lucky enough to live near Boston, you can hire me to design it and install it with you (or for you). Send me an email!