How to Water Trees for the Arizona Summer
The Sonoran Desert summer is known for the powerful “dry heat” interrupted by occasional monsoon storms during its latter half. This heat causes stress to plants of all shapes and sizes, from the most robust cactus to the smallest groundcover shrub. Native plants have evolved to handle this stress in the wild, but in manmade landscape environments even they can fall victim to heat damage if not cared for properly.
Most yards in the Phoenix area use drip irrigation systems. By properly utilizing drip irrigation, you can help the trees and shrubs in your yard establish strong, healthy root systems that will help them withstand the summer heat and resist wind damage in the long term. The duration and frequency of watering is vital to the creation of a strong plant. This article focuses on trees, but the same principle applies for shrubs.
The best strategy to help a tree survive the summer in the long term is to do deep, infrequent watering once the tree is established. Let’s say you have a drip irrigation system that supplies water to many trees and shrubs in your yard. You can keep everything on a regular irrigation cycle, but this cycle should emphasize duration over frequency, especially if your plants are already established for at least a year. Instead of watering trees twice a day for 20 minutes each, water them for, as an example, once a week for three hours. These numbers aren’t exact, as every yard is in a different situation with its soil, sunlight, and slopes, and every tree species has different needs. This idea applies universally, though.
In Arizona’s alkaline, high-clay soil, it takes a high water volume to soak deep into the ground. If you water your trees in a way more similar to the “twice a day, 20 minutes each” style, it’s very likely that the water doesn’t soak into the ground as much as it just moves around. In the long term, that method leads to weaker roots and more wasted money due to evaporation. It may seem overkill, but letting your irrigation run for a long duration, less often, leads to more water soaking into the ground and providing a more consistent water supply for your trees and all nearby plants. This is healthier for the plants and saves money in the long term. Once a tree is established, you can water it manually by leaving a hose trickling for several hours once every week (or even less frequently, depending on the species), and it won’t even need to have drips anymore.
The average nighttime temperatures in the valley have been increasing due to the many heat sources in the city (roads, roofs, parking lots, etc) creating a worsening “heat bubble” around the city. This makes survival more difficult for plants of all types. Thus, creating shade is absolutely vital for the future of the Phoenix area. If you want to create long-lasting, healthy shade trees that won’t fall over in a windstorm, this strategy of long but infrequent watering is pretty much a requirement. It will create healthy trees with robust root systems, which will save you money and improve the health of every plant provided with healthy shade thanks to your efforts.
At ELS Maintenance & Construction, we install trees and shrubs the right way, improving the likelihood of long-term survival and creating the shade that we need so badly. If you know of a community or commercial center that needs new landscapers, email contactus@evergreenaz.com and we can get started!
