Without water, plants cannot absorb nutrients. To water the garden is to allow the roots of plants to access the nutrients surrounding them in the soil. By watering, we also stimulate the growth of beneficial soil-dwelling microorganisms. It may sound simple, but watering is actually one of the gardening tasks that demands the most precision and experience to get right – especially during a drought or in a desert climate.
Simply watering your garden less deeply is not a useful method for watering during drought. If your irrigation is shallow, most of the water you apply will be lost to evaporation. Instead, a deeper and less frequent watering regimen will allow your garden to thrive and minimize your garden’s water consumption.
Surprisingly, allowing the soil to dry down between waterings actually forces roots to grow better. This means that established plants will put out root growth in every direction and maximize their potential for finding water. Once they receive the water they need, they have access to new nutrients in the expanded root zone.
While water-efficient gardening techniques such as mulching and reusing household graywater or rainwater are excellent ways to save water, learning which irrigation method(s) to use in your garden remains key and can be challenging.
In this article we will explore 4 methods of irrigation, including the pros and cons of each, which we hope will assist you in creating an irrigation plan that works for you, your garden, and your ever-changing climate.
First, however, a couple of rules of thumb regarding watering:
- When watering recently sown seeds and young transplants, shallow and frequent irrigation is best.
- When watering larger, mature plants, a deeper, slower and less frequent watering is best.
- Water your garden in the morning so plants’ leaves have time to dry out throughout the day. Wet leaves in the evening may lead to the spread of fungus and disease in your garden.
- Water around your plants, trying to avoid watering the base of the plants and the leaves themselves. This minimizes the potential for fungal blight on the leaves and encourages lateral root growth.
Once you have finished watering, dig down into the soil to see how deeply the water has penetrated. You might be surprised by how much water you must apply in order for the water to soak down even just half an inch.
4 Methods of Irrigation
Overhead Irrigation is sprinkling water on your garden using a sprinkler that attaches to the end of a garden hose. Overhead methods provide even coverage over your garden but a lot of water is lost to evaporation. It is also difficult to set the sprinkler so that it doesn’t water pathways and other areas that you’d rather not irrigate.
Flood Irrigation is used on flat ground where deep irrigation is required, using a system of levees and dams. This method also provides even coverage over the garden or field but can easily lead to a large loss of water (to evaporation and broken levees/dams).
Drip Irrigation is the most water-efficient method but coverage is not always as thorough as flooding and overhead irrigation. Drip can also have a significant up-front cost compared to other methods. Drip systems can be set with a timer so that you do not have to manually engage it each time you want it to run.
Caution: It is very tempting to set a timer on your irrigation system and walk away from daily or even weekly observation of your garden. Leaks and breakages can occur, filters and emitters can get clogged, batteries lose their charge after a while and power outages can cause your timer to default to its original settings. If you decide to use drip, make sure to continue to check on the system on a regular basis by running it while you are in the garden to minimize this margin of error.
Hand Watering is by far the most accurate way to water your garden. You apply water to the plants in the garden that need it using a watering can, a hose and nozzle, or watering wand. Attending personally to each garden plant in this way is precise, though it is easy to forget to water, not water deeply enough, or get carried away and water too much or too frequently.
When we work with beginning gardeners, we often observe a tendency to water too much. Remember, plants are resilient. If their leaves are yellowing, wilting or turning brown and leathery, they are likely being overwatered. As an extra challenge to yourself, see how infrequently you can water your garden. You will likely find that your plants grow better than they ever have before!
For more information on water-efficient irrigation techniques, see:
University of California Cooperative Extension – Drought Gardening Tips
The Urban Farmer Store – Drip Irrigation Resources
Roots Demystified – Robert Kourik