Column: Native plants a water-wise landscaping choice

JC AMBERLYN/Miner<br>
Lupine is a native wildflower sometimes found in yards.

JC AMBERLYN/Miner<br> Lupine is a native wildflower sometimes found in yards.

Plants suitable for our desert climate include native plants (plants indigenous to the local area), and plants from other arid climates. These types of plants are tolerant to desert-like conditions, low humidity, low rainfall, and alkaline soils. By using these types of plants, we can create a pleasing landscape while saving water and reducing plant maintenance.

Planting

Before choosing a plant, always consider the size it will reach when mature. Even though native plants grow slowly, they can become quite large. Careful placement of a tree or shrub, not under or above utility lines or too close to a walkway, will minimize pruning later. Pruning could ruin the esthetic beauty of a native plant.

Year-round planting here is possible. However, the best time to plant is late fall when soil temperatures are warm but the air temperatures are cooler. This will allow the plant to establish a strong root system.

Early spring is also good, but the root establishment will be slower. This may be a better option for frost-sensitive plants.

Prepare a hole three to five times as wide as the diameter of the root ball and no deeper than its height. Next, make sure the sides of the hole are rough and sloping. Fill the hole with water to check for drainage. If caliche or hardpan is preventing drainage, dig a chimney or a channel through these layers for adequate drainage. Native plants do not like to sit in water-logged soil.

The addition of compost or forest products is not necessary; native plants are accustomed to alkaline soils with high pH. To increase the water-holding capacity of very sandy or rocky soils, incorporate some fine-textured native soil into the planting hole.

Remove the plant from the container without breaking the root ball. Cut off girdled, kinked, or circling roots with a sharp knife or pruners. Then slice the root ball lengthwise approximately one-inch deep in two or three places. Place the plant in the hole and backfill with native soil. The top of the root ball should be level with or slightly above the existing soil surface.

Do not compact the soil by standing on it; use water to settle the soil. Immediately after planting, water thoroughly, taking care that the root ball remains level with the soil surface.

Avoid pruning at this time, but remove any nursery stakes. Mulch should be applied, but keep it a few inches away from the base of the plant. Native plants do not require fertilizer at planting time.

Staking

Staking should not be necessary in most cases. However, in very windy locations, temporary staking may be beneficial. Use two stakes per tree. Round, two-inch diameter wooden poles are the best. The use of metal pipe or rebar is not recommended.

Stakes should be placed outside the root ball, at a right angle to the ground, level and perpendicular to the direction of the prevailing wind. The height of the stakes after they are inserted into the ground should not extend into the canopy of the tree. Tie material should be wide and elastic - for example, polyethylene tape, plastic, webbing, or wire covered with hose or rubber tubing. Uncovered rope, wire, or string will damage the tree.

To determine the height to place the ties, hold the trunk with one hand a few inches above the ground. If the tree leans over, move a few inches up the trunk and try again. Continue this until you find the lowest point at which it will not bend.

Place the ties about six inches above this point, with one tie on each stake. Ties should hold the trunk firmly but not restrict movement from the wind. Movement is necessary for trunk development. The trunk and the tie should move as a unit.

Inspect the trunk monthly for damage and loosen the ties as the tree grows. Stakes and ties should be removed as soon as possible. Loosen the ties periodically to determine if the tree can support itself. Stakes and ties should be removed within one year.

Irrigation

Determining a plant's water needs has many influencing factors, including plant type, soil, weather, location and root depth. Although many desert-adapted plants can survive on rainfall, a supplemental watering is required for at least one growing season to promote establishment. Once established, approximately two to three years, watering may only be necessary during dry periods. Light, frequent irrigation creates shallow, weak root systems. Deep, infrequent irrigation encourages deep strong root systems that can tolerate longer periods of drought.

Always irrigate the entire depth and width of the plants root zone. In general, the average root depth for native trees is 12 to 36 inches, for native shrubs 12 to 24 inches, and for cactus 1 to 4 inches.

The average root zone (irrigation zone) is 1-1/2 to up to 4 times the width of the tree or shrub canopy. In a landscape setting, often times these root zones will overlap. Use a soil probe, a long screwdriver or a piece of rebar to determine how deeply and widely the water has moved. Prevent run off, and don't apply water faster then the soil can absorb it. Use drip irrigation, a soaker hose or a slow trickle from the garden hose.

Irrigate again when the soil dries out at least half-way. You can determine this by again using a soil probe and observing the plant's stress.

Obviously, water requirements will become more frequent during long dry periods. During summer months, irrigate at night or in the early morning. This will reduce water loss due to evaporation and wind. Observe plants regularly for signs of water stress such as wilted, curled or drooping leaves, yellowing or drop off of older leaves or dead stems and branches. Signs of excess water include brittle leaves remaining on the plant, wilted shoot tips, soft, smelly tissue, and the presence of algae or mushrooms. Native and low water plants are subject to root rot from excess water, especially in slow-draining soils.

Native and low-water plants come in a wide variety, everything between a 20-foot tree to a one-inch cactus, as well as all the colors of the rainbow. So no matter what your preferences are in plant size, shape or color, I feel confident you can find a native or desert adapted plants to fits the need.

For more information, contact The University of Arizona Mohave County Cooperative Extension, 101 E. Beale Street, Suite A, Kingman AZ 86401 or telephone (928) 753-3788.