With water scarce, minimize number of big plants in landscape
WATER is a scarce resource in the desert. Its price will always increase. Lowering landscape temperatures and irrigation go hand in hand. If water is used wisely, temperatures will decrease where water is applied.
Plants always require water when growing in the desert. Wherever plants are planted in the landscape, water is needed. Large, mature plants require more and more water as they grow bigger and bigger.
Do three things to your landscape to become efficient in its water use. Preserve only the plants that provide you and your home the most cooling and pleasure, improve the irrigation system and learn how to water. The last one — learn how to water — should be first. Learning how to water landscape plants enlightens the others.
Shade the south and west sides, walls and windows of your home and outside sitting areas. This type of irrigation creates “oasis landscapes,” perfect for the desert.
Plan to apply the most water to oasis areas. Trees and shrubs provide the most cooling for homes and sitting areas. There is nothing wrong with open areas, but they will be hotter. Make these open areas interesting to look at.
Shade doesn’t have to come from plants. Shade also comes from manmade structures.
Concrete and steel structures are the best choices for desert climates and don’t use water. There is nothing wrong with artwork in landscapes.
Consider man-made structures in combination with vines or smaller plants instead of trees. Small plants use less water than big plants. Where are large plants found in the desert?
Drip irrigation is among the most efficient ways of irrigating plants. But if you don’t know how to use it, it’s no better than flooding the landscape with water. Plants growing above 3 feet tall should be watered less frequently. Roots of tall plants will find water applied to the smaller plants and adjust their root growth to where water is applied in these areas.
A well-designed irrigation system and the knowledge how to use it puts you in charge of watering rather than the landscape telling you when it needs water.
Q: I have 13 40- or 50-foot-tall pine trees in my yard with grass growing beneath them. The grass doesn’t look good there, but it’s how these trees get their water. I also have scattered shrubs in the yard as well. Last summer my water bill hit $400. Is there any way to convert to desert landscaping and keep the trees?
A: You want to convert to desert landscaping to lower your water bill? The cost of water will always increase. About 70 to 80% of your water bill comes from watering your landscape.
The most efficient landscape uses about 10 to 15 gallons for each square foot of landscaped area. That’s what to aim for with an
irrigated landscape unless you want it to look like the desert. Yours is considerably more than that.
Tough decisions must be made. Determine which plants provide the most cooling and pleasure to you and remove the others. Every plant requires water.
Consider replacing plants with man-made structures that don’t need water such as gazebos and artwork. There is nothing wrong with open spaces provided they aren’t close to the house or where you sit outside.
The roots of pine trees are shallow and extensive in these grassy areas. Plant roots grow wherever water is available including your neighbor’s property. Look over the wall and see.
When water is applied to a lawn, the roots of trees are shallow when they should be deep. Tall pine trees need roots that are 3 feet deep to resist blowing over in strong winds. Once you start removing pine trees, the remainders will receive more wind and have less support.
Consider drip tubing rather than drip emitters where plants greater than 3 feet tall are growing in clusters. When grass is watered with pop-up sprinklers, usually 12 to 15 minutes is all that’s needed.
Not true when you convert to water deeply applied from drip irrigation. In a conversion to drip irrigation, the time increases from 12 to 15 minutes to one to two hours. To fine-tune the time needed, use a piece of steel rebar and apply enough water to wet the soil 3 feet deep around the pine trees.
The best time of year to do this is when the weather cools off in the fall, starting around the end of September in Las Vegas. Making this conversion in the fall gives you the fall, winter and spring months to force large tree roots to grow deeper in the former grassy areas.
Q: I bought a few Spartan junipers for a hedge or screen instead of Italian cypress. They are now about 8 feet tall and starting to fill in. How much water do they need?
A: Spartan is an upright juniper
that grows to about 15 feet in height and 3 feet in width when mature. Always water them so the soil has at least one day without water to dry out before the next irrigation.
Like Italian cypress, they benefit from periodic deep watering rather than daily irrigations. If watered daily, they will likely die from root rot.
Because of their smaller size they are a better choice for a single-story home than Italian and other cypresses such as Arizona and Leyland. Like Italian cypress, other types of cypress and junipers may have problems with spider mites during the hot summer months so wash them off with a hose during those times. If your soil is heavy or doesn’t drain easily, consider planting on top of a rise in the landscape, amend the soil for drainage and use drip irrigation.
The problem with upright junipers is that they are untested for extremely hot, dry and isolated locations found in some desert landscapes. A better plant choice for those areas is our native Utah juniper except that it can get large like Italian cypress but has the same root rot issues.
Other upright Chinese junipers to consider besides Spartan include
Blue Point, Hetz and the Rocky Mountain upright juniper Skyrocket, which grow to about 15 to 20 feet tall and 3 feet wide. Because of their unknowns to heat tolerance, I am usually hesitant to recommend them.
Q: My bay leaf bush developed lots of brown leaves. The plant is in our courtyard facing north. There are three more of these plants in this courtyard not affected by this problem. A few gardenias next to this plant have the same problem. What is causing it and what is the remedy? A:
Bay laurel, sometimes called sweet bay, is used for cooking and usually grown into a small tree about 20 feet tall and 20 feet wide. You can prune this tree into a shrub but be sure you have room for four of them. Their planting distances apart would be 10 to 15 feet if pruned every year.
The browning of leaves of one and not the others is typically water or soil-related. If it’s water-related, the side and plants facing or receiving the most light will have more brown leaves than sides sheltered from the light. If this is a soil problem then the brown leaves would be distributed more evenly throughout
the plant.
Check for plugged or blocked drip emitters. In late spring or early summer, these trees should get watered about twice a week. Probably in the summer when it is hot then maybe three times a week, four at the most. Always skip one day when watering these plants.
The color and dig-ability of the soil surrounding it should give you a clue if there is a soil problem. Loose, dark brown or chestnut-colored soils will be fine for both plants. Wood chips that will rot for future soil improvement keep the soil healthy if applied on top of the soil under these plants.
Q: I bought a 15-gallon sweet bay laurel multitrunk tree last spring and kept it in the pot all this time. The pot gets morning sun and afternoon shade. I only water maybe once a week checking with my moisture meter when it needs water, but the leaves are brownish and there seems to be damage on branches. A:
Irrigation of plants growing in containers is a bit weird mostly because the water is distributed in a strange way due to the container and the artificial soil mix. I wouldn’t trust the soil moisture meter to tell me when to water.
Plants in containers are commonly watered daily when it’s warm or hot or every other day during cooler weather. Never once a week.
Plunge the container and plant in a larger bucket of water and let it soak for about one hour. During warm weather, irrigate this plant daily. That plant needs to be repotted if you are going to keep it in a container for another year.
If you plant it in the ground, be sure to cut off any roots that are kinked, broken or distorted. You can lose about 50 percent of the roots before you have to prune the top of the plant back to compensate for the root loss.