Why Drip Irrigation?
July 29, 2013 at 10:24 AM
What plants need
It might be stating the obvious, but all plants need water. Unless you live in a rainforest, the question is how to conveniently, efficiently and reliably provide water to plants that require more water than rainfall can naturally provide.
Vegetables are particularly sensitive to the amount of water in the soil in which they are growing. Too much and the roots will drown or the fruit will taste watery and bland; too little and plants will wilt and die of dehydration. What makes them happiest is even, consistent moisture levels throughout their life cycle. So avoiding any dry spells that cause the plants stress will result in higher yields and healthier plants that can better withstand pests and disease. Most veggies are happier with even soil moisture levels. In the heat of summer, just like us, our plants like to be well hydrated.
Also, many plant are susceptible to fungi and mildew that grow on the plants leaves or stems. Fungi and mildew thrive in moist conditions. This is why sprinklers or overhead watering can cause problems, keeping plants wet for long periods and creating a perfect environment for disease to spread and plants to suffer. Tomatoes, squash and beans particularly dislike overhead watering.
So how should we water our gardens? There are many different techniques: overhead spray, such as lawn sprinklers; hoses and shower nozzles; soaker hoses; and drip irrigation. Most of these approaches have the disadvantage of wasting a lot of precious water, either to the air via evaporation or by simply putting water where it is not useful to the plants, only to then evaporate on the surface.
What is drip irrigation?
Drip irrigation uses pipes or tubing on the ground to move the water around the garden and emitters or “drippers” that allow a controlled amount of water to leave the pipe and drip down, to be absorbed into the soil and then by plant roots.
Drip systems require a pressure regulator and filter to protect the tubing and emitters. Typical household water pressures can blow the fittings apart and small particulates often found in home water systems can plug emitters.
In the installations we do for our clients, we either use an automatic timer or we connect to an unused zone of an existing irrigation system. Either method allows the water times and duration to be controlled with ease and reliability. Vacations have been the death of many a beautiful garden when that friend or neighbor simply forgot to water for a few days in the heat of the summer.
Pros and cons of drip systems
- Placed near the plants’ root zones, the emitters conserve water compared to other methods by watering only where needed and avoiding overspray and evaporation. The water is applied to the soil at a slow rate, minimizing soil saturation and run-off.
- Many studies have documented water savings of 60% to 70% when compared to other methods. This translates to significant cost savings as the cost of municipal water supplies continues to increase faster than inflation in most communities.
- Drip irrigation means fewer weeds, as you are not watering unplanted areas such as pathways or in between garden plants.
- The initial cost of installing a drip system is generally higher than that of soaker hoses or sprinklers.
- The filter needs to be cleaned and the tubing flushed (to remove algae growth) annually. If the drip system is properly installed, this should take no more that 15 minutes for a typical veggie garden, however, and requires no tools.
We believe that the pros far outweigh the cons and have installed drip irrigation for all of our veggie beds as well as most of the plants and shrubs in our own yard.
If you have a timer installed, make sure that it has the capability to run four or more start times per day. In our raised beds, we run up to four cycles in a day in the heat of the summer with duration of no more than 15 minutes using 0.5 GPH emitters. These low rate emitters prevent the soil directly under them from over-saturating, causing the water to run out of the bed. Short durations, multiple times per day, allow the water to be absorbed laterally as well as down into the bed.
Whether you hire someone to do the drip irrigation installation or do it yourself, don’t install cheap big-box store drip fittings. Those that have what I like to call “Chinese finger puzzle” fittings that cannot be taken apart after installation and are a pain. Drip lines in the systems we install can easily be taken apart, repaired or replaced without having to redo the entire system.
I cannot say enough good things about our vendor, Drip Depot in Medford, Oregon. They carry commercial-grade, high quality systems and parts, ship worldwide, and have the best customer service I’ve experienced for an on-line company.
For do-it-yourself folks with raised beds, we sell inexpensive downloadable drip irrigation plans on our website for any standard 4’ wide beds as well as as for our Mayan pyramid frame design. The plans include illustrated step-by-step assembly instructions and tools and materials lists, and greatly simplify the complexity of doing a drip system installation.
--Larry Lewis, CLP
I purchased your drip irrigation plan for raised beds and then modified it to work for my two animal watering trough raised beds (8 foot by 3 foot). Your plans were excellent - well written and easy to understand.
Anyway, my question for you is what do you do to start seedlings for root crops such as parsnips, carrots and beets that are located many to one square foot area? How do you keep those areas evenly moist during germination?
We direct sow parsnips, carrots and beets, planting parsnips and carrots 16 per square foot and beets nine per square foot. We make shallow indentations in the soil (1/8") and drop in two seeds per hole, as opposed to just scattering seeds. That way we achieve nearly 100% germination and have to do very little thinning. And we hand water those squares daily, twice daily in summer, until the seeds germinate. Where that isn't feasible, we punch a hole in the drip tubing and add a 1/4" drip line connected to a little sprinkler emitter on a short stake, which then sprinkles a small area of the garden until we turn it off or disconnect it and add a goof plug to plug the hole. Does that make sense?