Take this quiz and see how you stack up against other desert gardeners.
1. A dead branch on a peach tree in summer usually means a problem. The problem is often:
A disease
B. Insects
Cheat
D. water
E. Pruning
2. A healthy plant that has been in the landscape for five years and fits comfortably in a 5 gallon growing container should be watered with:
A. 1 gallon of water every time it is watered
B. 2 gallons of water each time it is watered
C. 5 gallons of water each time it is watered
D. 10 gallons of water each time it is watered
E. 15 gallons of water each time it is watered.
3. The best time to plant landscape trees and shrubs is:
A. Any time of the year
B. When it’s coldest
C. Just before it gets hot
D. Just before it gets cold
E. Spring or autumn months
4. Desert trees (xerian trees) use less water than non-desert trees (mesian trees). Right or wrong.
5. When using systems to reduce summer cooling costs:
A. Shade all the walls of your home with evergreen plants.
B. Shade the north and east sides of the house with deciduous plants.
C. Shade the south and west sides of the house with deciduous plants.
D. Shade the east and west sides of the house with evergreen plants.
E. Shade the north and south sides of the house with evergreen plants.
answers
1. Any of these answers could be correct, but the most common reason a single or multiple south or west facing branches die on a peach tree in summer is because of bores (insects). In our desert part of the country, the flattened apple tree drill is probably the most common drill; a flat-headed “worm” when young, but a winged beetle when mature.
These bugs most often lay their eggs on trees in early spring, but it could be done anytime until early summer. As soon as these eggs hatch, the tiny worm or larva snakes its way into the tree, where it feeds on its juicy parts just under the bark. Here it gets bigger, from a creamy white, flat-headed worm to a darker winged beetle and finally pupates a few months later. As an adult, it flies to find a partner and start the egg process over.
2. For some who need help knowing how much water to give a plant each time it is watered, this rule of thumb can help. A 5 gallon plant should get 5 liters of water. A 15 gallon plant should get about 15 gallons of water each time it is watered.
Water in the soil serves as a storage reservoir for the plant roots, from which they can draw until the next irrigation. The first water used by the plant is in the upper parts of the soil. Later it will attract the water deeper in the reservoir as the topsoil becomes drier through evaporation and plant use.
Where there is water, plant roots grow. If they pull out of the deeper water, roots will grow there. If they constantly pull out of the shallow water through daily watering, plant roots will grow shallow. That is why it is important not to water bushes and trees every day. Shallow, frequent waterings encourage the growth of shallow roots. Shallow-rooted plants later become problem plants.
3. The best time to plant landscaped trees and shrubs is always in the cooler months of spring and autumn, never just before or during the hottest months. In the Las Vegas area, planting time is usually from late January to about March in spring and from late September to October in fall.
Avoid planting trees and shrubs during the coldest and hottest months. Planting just before it gets hot creates problems unless you have no other choice. Planting during the heat or cold increases the likelihood of plant death and the time it takes for them to be difficult to establish.
4. This is a tricky question and very confusing. For this reason, it is important to pay attention to the full-grown size of a tree or shrub when purchasing and placing it in your landscape. In general, the bigger a plant can get, the more water it will need later when it gets bigger in the years to come.
Not my problem, you say? Yes it is.
A large plant is difficult to remove emotionally and financially, whether it is you or someone else. As a tree gets bigger, it needs more and more water.
Desert trees (xeric) do not naturally have low water consumption. But they can handle less watering. Desert trees and shrubs will “talk to you” and tell you it is time for a drink. This is what gives them an advantage when growing in the desert.
Desert trees can hold as much water as you want to give them. They take that extra water and turn it into luxurious growth. This is why you see such long, clumsy growth in young desert trees after getting plenty of water. This lush growth, along with their leaf density (they drop their leaves when the water runs out), can be used to gauge when to water desert trees or not.
5. There are several ways to reduce summer cooling costs. But one landscape method is to shade the south and west walls and windows of your home with deciduous, not evergreen, trees and shrubs. It is even better if you use xeric plants (desert trees and shrubs) to shade these walls and windows as you will water them less often and save water. Of course, there is no water saving if they are not on separate irrigation valves.
The rule of thumb is to plant trees and bushes at a distance of about half their full-grown height from the house wall. This means a 30 foot tree should be planted about 15 feet from the foundation. You can plant closer, but keep in mind that they will need to be pruned so they don’t grow away from the house.
The roots of plants planted in the desert grow where there is irrigation water. A minimum of 3 feet from these walls will reduce the likelihood of root penetration and water damage to your concrete foundation.
Keep the soil surrounding your home dry and weed-free. This is less inviting to insects that might invade your home during the spring and fall months.
Bob Morris is a horticultural expert and Professor Emeritus from the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.
