By Warren Tenney
So you’re looking at your trees and plants baking in the desert summer sun and you’re beginning to feel just a little sorry for them. Save your sympathy. Desert-adapted plants are built for this weather and will do just fine. Adjustments do need to be made to their care during the summer, but many homeowners and businesses make adjustments that harm – not help – their trees, grass and plants. Conservation specialists from AMWUA member cities offered these five common summer landscaping mistakes.
1. Thinning trees before monsoon season. For some homeowners, “thinning” a tree means removing all the smaller inner branches and maintaining the growth at the end of longer branches. This is a mistake for several reasons. First, it exposes the inner branches to sun damage. Second, it removes leaves, which are a tree’s energy source, and decreases its ability to defend itself against pests and diseases. Third, it leaves all the weight at the end of the branches. This is called “lion tail pruning” and makes the branches more vulnerable to breaking during heavy winds. It is better to prune just before growth starts in spring. If you must prune, confine the cuts to the outer 20 percent of the tree canopy and never remove more than 25 percent of the living leaves, stems or branches annually.
2. Running the irrigation system for short durations throughout the day. This seems like a great way to keep your trees, shrubs and groundcover happy, but it does more harm than good. That water evaporates and never reaches the roots. When summer temperatures are peaking and humidity is low, your landscape needs a deep watering once a week. This allows the water to sink deeper into the ground, where the clay soil is built to hold water as a reservoir for desert plants. (Remember the simple rule: water 3 feet deep for trees, 2 feet deep for shrubs and 1 foot deep for smaller plants. Use a slender metal rod or long screwdriver to test your watering depth. You can probe easily in moist soil and it becomes more difficult in dry soil.) Even grass will do better with two longer soakings a week, instead of a little water every day. Sometimes when you irrigate sloped areas, especially lawns, water will eventually run off onto the sidewalk or street. Use the “cycle and soak” method to stop this waste and give your plants and grass an even watering. Break up the watering into a stop and go cycle. For example, run your irrigation system just to the point prior to runoff, shut it off for 30 – 60 minutes and water again. This gives the water a chance to soak into the ground.
3. Shearing, shaping and over-pruning shrubs. It’s never smart to shear desert-adapted shrubs. Losing all that natural foliage forces a shrub to grow a shell of leaves that must work too hard to manufacture the sugars the plant needs to grow. Eventually, you’ll notice the shrub gets woody inside from lack of sunlight, woody holes begin to appear from the stress and the shrub dies. Think of foliage as a way a tree or shrub shades its inner core and roots from the intense sun. Leave your plants and trees alone for the summer and prune them delicately and minimally when the weather is cooler. Remember to select the right plant for the right space. Before planting a shrub or tree, make sure it has room to grow and spread. This helps to cut back on the need for severe pruning.
4. Adjusting your irrigation system twice a year. Landscape watering needs to increase incrementally in the spring and begin to decrease in July during the monsoon season’s higher humidity and rain. Adjusting your watering times gradually, preferably monthly, will save water and save you up to 30 percent on your water bill. That’s why some cities will help you pay for a new smart irrigation controller that adjusts watering cycles based on weather and the amount of moisture in the soil.
5. Failing to regularly check your irrigation system. It’s hot out there and it’s easy to leave the watering chores to your irrigation controller. Homeowners and businesses often set irrigations systems to run during the night. It’s a good idea to water when temperatures decrease after sunset, but there’s no one around to spot a broken emitter or water bubbling up from the ground due to a broken line. A broken sprinkler head can waste up to 7 gallons of drinking water – per minute. A leak also means that somewhere in your landscape some grass, plants or trees are not getting enough water to survive. Take a walk periodically to see if there are signs of any leaks. Watch your water bill for spikes in use. These spikes could indicate a leak. It’s worth your while to turn on your irrigation system monthly and walk your property to look for leaks. Ask your landscaper to manually turn on your irrigation system and alert you to any leaks. AMWUA’s Smart Home Water Guide is an easy step-by-step guide that can help you find and fix leaks. Many cities also offer free irrigation classes to help you.
Here’s a bonus tip: The summer sun rises a little farther north from where it rises during winter months. Plants that likely live in shade in the winter may have to stand up to a tough few hours of afternoon sun in the summer. Bring your potted plants into the shadier areas of your yard or porch. Planting a few hardy, fast growing trees, such as Palo Verdes, or installing some yard art, such as a shade sail, can provide relief for those plants hardest hit by summer sun. If you are just designing or redesigning your landscape, keep in mind the seasonal adjustment of sunshine. It can guide you to choose the right trees, shrubs, plants and groundcover for each section of your yard. AMWUA’s landscape pages help you select, install and succeed at getting the maximum beauty out of your landscape with minimum care – and just the right amount of water.
For 48 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit www.amwua.org.