Aug 08 2016Share

Monsoon Season: 5 Common Landscape Mistakes

By Warren Tenney

In writing about the monsoon season, I'm hoping we do not jinx having more storms. The monsoon season in the Valley is a great time of year for suddenly cooler temperatures and extraordinary sunsets, but it makes caring for desert landscapes a bit more mysterious. There's more weather than usual: humidity, dust, rain and high winds. With lots of anticipation for more monsoon activity, we asked conservation specialists from a few AMWUA cities about the five most common landscaping mistakes during the monsoon season. Here's what they told us.

1. Watering too often. Some people are so concerned with rising temperatures they make the mistake of watering plants every day. Watering too frequently can keep the soil too moist and lead to rot, fungus and other diseases. Plants thrive on monsoon humidity.  They do better when you water less frequently but with deeper soakings, about 2 feet deep for shrubs and three feet for trees. (You can measure by sinking a pointed wooden stake into the ground.) Watering deeply and less frequently creates an underground reservoir of water for plants and trees that will not easily evaporate and will encourage healthy roots. Large desert trees do best with very little water during the summer. This discourages heavy top growth and soft wet soil, which makes it easier for them to uproot and fall over in high winds. When you do water trees, water out to the edge of the tree’s canopy. This gives trees a longer, deeper and stronger root system to steady them in a storm. Landscape Watering by the Numbers offers you more precise information.

2. Wasting rainwater. If it has rained about a half inch in your neighborhood, you can turn off your watering system. That saves you money on your water bill and saves water for all of us. Better yet, you also can contour your yard to help your plants and trees get the most out of each storm. Sunken gardens and deep wells around your trees help to slow, to spread and to sink rainwater instead of allowing it to run off your property.  It’s the simplest rain harvesting technique and takes nothing more than a shovel, a little energy and thoughtful placement of plants. Consider this: 1 inch of rain on a 1,000 square-foot roof produces 600 gallons of runoff. The Valley receives an average of 7 inches of rain a year. It makes sense to plant at the roofline and to build swales to direct runoff toward trees and plants.

3. Leaving trees without proper support. Swaying in the wind can help young trees grow stronger. The wind also can uproot them if they are not staked properly. To properly stake a tree use two stakes 6 inches from the trunk and gently attach them to the trunk with looped ties that allow the tree to sway in the wind. Allowing the tree to move with the wind creates a dense wood and strong trunk that will help keep mature trees standing despite the weather. Properly pruning helps established trees stand up to monsoon winds. Here are four pruning tips to help keep an established tree standing and avoid losing limbs during storms: 1) do not cut off lower limbs, 2) do not top a tree (shear off the top), 3) do not cut it into an umbrella shape, and 4) do not aggressively thin a tree leaving excessive foliage on the end of branches.

4. Applying herbicides during rainy weather. Rain is rarely gentle during the monsoon. Hard and fast rain rushes across your yard carrying any herbicides you’ve applied into the streets. From there it flows into storm drains or catch basins, which are usually located along street curbs, and into storm drain pipes deep underground. Most of this untreated runoff empties directly into riverbeds, washes and retention basins in city parks. Herbicides only add to the pollution the runoff carries with it. You can learn more about the importance of storm water at Stormwater Outreach for Regional Municipalities (STORM). Hand pulling weeds out of moist soil after a storm is easier and best for the environment.

Broken Spray Head

5. Abandoning an irrigation system. No one can blame you for getting out of town for most of the summer and never experiencing the monsoon. (Perhaps you’d just prefer to stay indoors and abandon the yard work for a few months.) Here’s the problem: many homeowners trust their yard to an automated irrigation controller. Electrical storms can get your irrigation timer off schedule or even set your controller back to a default schedule (and sometimes cause irreparable damage). While the controller may be reliable, your pipes, sprinkler heads and drip lines are less so. Drip lines are particularly susceptible to weather. High temperatures, dust, and rain can clog, crack and break emitters and lines so each time that reliable controller comes on plants don’t get watered or gallons of wasted water pools in your yard. Pooling water gives mosquitoes a place to breed, wastes your money and everyone’s water. Check sprinkler heads for mower damage. Grass and leaves also can clog sprinkler heads. If you leave for part or most of the summer, make sure a neighbor, friend, family member, or a gardener regularly walks your yard while the irrigation system is running and is prepared to spot and stop any leaks. AMWUA’s Smart Home Water Guide can help.

Enjoy the monsoon season along with your plants and trees and keep this in mind: the monsoon season means Fall weather is getting closer.

For 46 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


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