Let’s repeat that together…,
Water is ESSENTIAL for all living things.
Regardless of whether you have a fruit tree orchard, vegetable garden, drought tolerant desert shrubs, shade trees, evergreens or lawn, they all require water. The question is, “how much?” This simple two-worded question is the single most asked question at the nursery and proves to be one of the most not-so-simple questions to answer.
There are many factors to consider when establishing a watering schedule for plants. The most important factors to consider are soil texture and plant specific requirements. Keep in mind, these factors are always changing, so a plants watering needs will also change.
Soil texture might be the most important factor to consider. The makeup of the soil could vary from clay, silt and sand, or a combination of all three, in any given area of the yard. Knowing the difference will be key to proper irrigation.
Out of the three, sand has the largest particle size. Therefore, sand has the largest pore space between each grain of sand and water will drain the quickest. This is why, if you have mainly sandy soil, the plants will dry out quicker and more frequent watering is necessary. Sandy soils do not keep a moisture level that holds enough water to benefit the fine absorbent roots that provide the plant with water and nutrient uptake.
Clay has the smallest particle size. It is extremely fine. This means the pore space between each grain is so small that water remains in the pore space, resulting in poor drainage. Water doesn’t easily percolate down and has the potential to flood. Once it finally penetrates, water stays too long in the soil, resulting in an imbalance between water and oxygen, choking the root system and causing death to the plant.
The size of silt is in between clay and sand. Although it might seem logical for it to be the perfect texture, it’s not. The ideal soil profile is a mix between the three textures, referred to as loam, which has an equal amount of water retention and oxygen.
The goal of irrigation is to provide an environment conducive to root growth. Once the balance between organic matter, minerals, water and oxygen have been established, the fine absorbing root hairs will grow. These roots take up water and minerals, supplying them to the rest of the plant. The result is a vigorously growing plant. As the plant grows, it is necessary to provide additional water by expanding and adding irrigation to the root system.
Moisture meters are wonderful tools to measure the amount of moisture in the soil. If you don’t have a moisture meter, it is possible to gauge if there is adequate soil moisture by hand. Simply grab a handful of soil from approximately 4-6 inches deep, close to the plant’s dripline. (The dripline is an imaginary line directly under the branch spread of a plant, where should it rain, the raindrops would fall from the outermost branches and create a dripline on top of the soil). Once you have a handful, give a squeeze. If water releases between your fingers or the sample is muddy, the soil is too wet. If you open your hand and the sample falls apart, the soil is too dry. If you release your grip and the soil keeps the shape of your hand, your moisture level in the soil is adequate. Another easy way to gauge, is to observe the wetting patterns on the ground. Below the plant’s canopy should be an even wetting pattern extending, at minimum, to the edge of the plants drip line.
As the seasons change, the plant’s water requirements will change. This is when it’s important to understand your plants requirements and sun exposure. All plants transpire. Transpiration is when water vapors are lost through the leaves of the plant. It’s the plant’s way of cooling its leaves, think of it as “plant perspiration”. A plant in full sun will transpire quicker than a plant in shade or partial shade. Therefore, a plant in an environment that is too harsh will be drawing water from the plant’s water reserves, causing it to expel water quicker than it can draw up from the soil, resulting in dieback. This brings us back to the “right plant in the right place” motto. A drought tolerant plant will need less irrigation than a moderate water plant and will do much better in full sun exposure. These plants usually have smaller leaves and require less transpiration, needing less irrigation. Evergreen plants have thick waxy leaves that require more water and transpiration during the extreme heat of summer. When choosing plants, consider creating “hydrozones.” These are plant groupings which have similar watering requirements. Which makes setting the irrigation timer simple and efficient.
For an in-depth breakdown of irrigation requirements for each type of tree and/or shrub during each season, please read STARNOTE 900A “How Much Should You Water Your Shrubs and Trees?” available at www.starnursery.com and the Star Nursery app.
Lawns have different irrigation requirements and soil texture plays an important role. Therefore, it’s essential to prepare the soil of your lawn in the early stages of planning. If the lawn is already established, add top dressing at the rate of ¼ inch coverage to improve the soil. Organic matter helps breakdown any compaction that might have bound up the soil just under the lawns root system. In addition, it is advisable to implement a “soak cycle.” Newer model irrigation timers have this setting and are relatively easy to program. The purpose of the “soak cycle” is to run water for one minute to each zone or station, then immediately follow up with normal scheduled watering. This process “primes” the soil, helping the water absorb and improve infiltration, preventing runoff and encouraging better absorption.
For an in-depth breakdown of irrigation requirements for lawn, please read STARNOTE #900B “How Much Should You Water Your Lawn?” available at www.starnursery.com and the Star Nursery app.
The Southern Nevada Water Authority has established seasonal watering guidelines and restrictions for all residents. They can be viewed at https://www.snwa.com
Irrigation is an important and ever-changing aspect of plant health, vitality and should be evaluated often. Until a plant has been established, it’s hard to determine optimum soil moisture against the needs of the plant. Should you need additional information, our skilled staff at all Star Nursery locations are always ready and available to help. For a service fee, Dr. Q will make a house call and you will receive up to one hour of consultation. To set up an appointment, call (702) 771-STAR (7827), email- firstname.lastname@example.org or visit your local Star Nursery location.