At best, gardening in Arizona's desert soils can often be a challenge. Most of our municipalities utilize the concept of "water harvesting" by building retention basins and collecting natural runoff. This is seen in the many neighborhood parks throughout our cities. In most cases this is an excellent method and certainly wise for water conservation. Unfortunately, it is not seen frequently in today's newer housing developments. Regardless of whether or not you are able to utilize water harvesting, with proper water management you can realize success and conserve water by following a few simple rules.

Rule #1: Deep Water

Our soils contain high amounts of salts. Some of these salts are detrimental to native and non-native plants. Damage is normally seen as discoloration (yellowing) of foliage and the appearance of burnt edges around the leaves. With frequent watering at predetermined amounts these salts build up in the soil. By supplementing this with infrequent deep watering the salts are pushed down and away from the root zone. This also increases oxygen and facilitates nutrient movement in the soil. The amount of water is entirely dependent upon the soil type but in most cases you will want to saturate the soil, then when the water has drained, re-saturate and repeat several times.

Rule #2: Acidify

For highly alkaline (high pH) and high calcium soils, the soil should be acidified to increase water penetration and holding capacity and to release bound nutrients. This can be done with the addition of a water soluble sulfur, which exchanges the sodium salt with sulfur allowing salt and calcium to leach. This acidifies the soil and breaks up the hard caliche desert soils. Use Disper-Sul with Iron and Manganese or First Step.

Rule #3: Mulch

Mulching serves several purposes and is essential to successful arid gardening. The addition of mulch as a top dressing and soil amendment reduces water loss by evaporation and helps to maintain moisture levels. The addition of mulch also prevents many types of weeds from germinating and keeps the soil cooler during our hottest months. It also provides humic acid, a bio-culture environment and holds nutrients.

Rule #4: Proper Watering System

The installation and maintenance of a proper irrigation system is extremely important. Drip systems with the proper size emitters (1 –1½ gallons/hr) are necessary for most shrubs and trees. Large trees and beds often need the addition of bubblers because of their need for extra water and leaching. The use of a timer system, or clock, establishes watering "zones" which allows plants of similar water requirements to be irrigated alike, that is: lawn areas on one zone, low water plants on another zone, and high water plants on yet another. Trees should always be on a separate system from bedding, shrubs and turf.

Another important point in drip systems is maintenance. Not only do drip emitters become clogged and need to be replaced, but the number of emitters often needs to be changed as well as moved as the plant grows larger. A few emitters may well suit a newly planted shrub, but as the shrub grows its water requirements increase and the quantity of the emitters eventually must be increased to meet this need. This is particularly important with trees. Two to three emitters are typically placed out from the trunk of a newly planted tree. For a young tree this is normally fine, but as the tree grows, the number of emitters and their location needs to be adjusted. Continue to increase the quantity of the emitters as the tree grows and move the location of the emitters to the outer skirt of the canopy.

Rule #5: Proper Watering

The most elaborate and sophisticated irrigation system is worthless unless used properly. As mentioned in Rule #3, different plants have different water requirements. The duration of irrigation is also dependent upon the time of the year. With Arizona's diverse temperature ranges it is important to adjust your watering with the season. The chart below gives typical number of hours and days per week that you should be irrigating. If your soil is excessively heavy or excessively sandy, you may need to make slight adjustments to the following recommendations. And remember, if you aren't certain as to the type of soil that you have, or need any additional information, just ask your Gardener's World Pro. We are here to help ensure your gardening success.