Q: I am in the process of redoing my front yard to water-smart landscaping. We had to pull out an olive tree because olives and rock do not mix, and we cannot seem to control the growth of the olives even when spraying twice a year. I saw an article in the paper where the water company wants us to plant water-smart trees. However, it does not tell me which trees are water-smart. Can you please give me some suggestions? I have a corner house so it will be in the front yard, full sun.

A: Water-smart trees are supposed to use less water than other types. But of course, if you give it more, it will use it. Instead of using 4 to 5 feet of water under their canopy, water-smart trees can survive with about 2 feet of water applied under their canopy.

Most of them can be planted in full sun. Simply putting lower water use trees and shrubs will not change their need for water. They must be managed.

Still water deep but not very often. Instead of watering daily, water with more minutes and give the plants a rest without water.

Water instead three (or maybe at the most four days) per week. Increase the minutes they are watered to compensate for the rest days. Do this during the heat. Make sure the plants have at least 2 inches of mulch on the surface of the soil. This mulch will give the plants one day of rest without water between irrigations.

There is a list created by the Las Vegas water company that you can use. Try searching online for Southern Nevada Water Authority and “water smart plants.” You will see two lists: one you can print and one you can search.

Other places to look include “AMWUA,” which stands for Arizona Municipal Water Users Association and is the list for Arizona users.

I believe the water companies want you to use a website that focuses on low-water-use plants appropriate for this area. Remember, it is the landscape plant size and the total number of plants in your landscape that determines landscape water use.

Firstly, reduce the total number of plants in your landscape. Eliminate plants that are not necessary. This means some will have to be pulled out.

Water delivered to them is shut off or diverted to important and necessary plants. It is easier to reduce the number of minutes delivering water than add more emitters later. Space emitters about 18 inches apart.

Next, either reduce the height of tall plants by pruning in the late fall or winter or use smaller plants. The plants should grow to a mature height similar to your home. Use these plants to provide shade on the south and west sides where possible.

Be creative and leave open spaces in the landscape. If they must be filled, use additions that don’t use water (textural changes using different sizes of rock, wall art, landscape lighting).

As far as olive trees go, I agree the fruiting is difficult to control but the tree itself will take a lot of abuse including rock.

Q: Since I had no luck with mango seeds and very minimal luck getting avocado to sprout (I get roots but no sprouts), I thought I could use more frustration in my life and try cherry pits. Is this possible to get them to sprout and what is the best way to do it?

A: I have not grown cherry trees from seed. I have grown both sweet and sour cherry trees in our desert, but they were purchased already grafted to a rootstock. Cherry trees are usually purchased grafted, not sprouted from seed. This is because grafted trees are oftentimes different from a tree that has been grown on its own roots.

In any case, have fun sprouting the seed but use it as a flowering ornamental tree. Sour cherries are somewhat tart (traditional pie cherry), a smaller tree (10 to 15 feet tall, think Montmorency and North Star varieties) and produce a small amount of fruit in four or five years in the desert. Sweet cherries are more temperamental and may or may not produce fruit. I believe it is due to our low humidity.

The seed is in a hard pit produced at the center of the cherry fruit. Select seed from ripe fruit that you want to grow (sweet vs sour, good ripe color, free from deformities, and good size). The cherry pits, or seeds, are put in the refrigerator, moistened and kept there for at least one month.

The moist seed sprouts in about one month or longer at refrigerator temperatures and is then ready to plant. Place sprouted seed in a 1-gallon container or smaller peat pot first before moving it to a larger container. Larger containers are OK to use when the plant is bigger.

Cherries, both sweet and sour, are hit and miss at fruit production in Las Vegas. It seems if you have higher humidity in the landscape (nondesert areas or lawns and pools in the desert), you have the best chance of producing fruit.

They will always produce flowers that attract bees when they are sexually mature, but actual pollination of the flowers may be sensitive to humidity. Unexpectedly, the same is true in the desert of the Hachiya variety of persimmon. An abundance of fruit of both cherries and Hachiya persimmon sometimes occurs after a rain.

You realize, I hope, that the resultant seedling is sexual in nature. That means that the seedling is combined from two different parents or two different varieties or types of cherry trees. Buying a grafted tree makes sure the fruit is true to the variety.

Q: How many gallons of water can be used from ½-inch drip tubing without running into problems? How about ¾ inch?

A: Professionals use several different names. I call these types of tubing either “blank tubing” or “drip tubing.” Both types of tubing come in either ½-inch or ¾-inch diameters.

Blank tubing doesn’t have any emitters built into it. Blank tubing is either made to carry water to a new location or have drip emitters punched into them at different locations.

In 100 feet of tubing, the ½-inch blank tubing (drip and blank) can handle about 250 gallons in one hour. The ¾-inch tubing can carry more water than ½-inch tubing. It can handle about 480 gallons of water, in total, before you should stop. The amount of water to use has to be tallied or calculated for each run of tubing from an irrigation valve.

Individual drip emitters are usually inserted into blank tubing. These inserts either are directly inserted into the blank tubing or connected to it with ¼-inch tubing.

Blank tubing is less expensive than drip tubing because of the embedded drip emitters in drip tubing. Make sure fittings used are the same size as the tubing (there are three nearly identical sizes of ½-inch tubing).

Q: I read somewhere not to use the type of drip emitters that you have to open to get water. What say you?

A: I don’t like what are called variable output drip emitters (the kind that releases a different amount of water depending on how much you open it using a dial). You don’t know how much these drip emitters are releasing because there is a loss of precision.

Opening it varies the output of water from zero gph (no water) to 10 gph (wide open). It depends on how much it’s opened, and it doesn’t tell you the amount of water it delivers. Wide open might be more than 10 gph for some manufacturers.

For me, it’s like playing whack-a-mole when variable output drip emitters are used. Using variable-type drip emitters makes it difficult to tally how much water is used.

Q: Can you tell from the attached pictures what might be happening to our mastic tree?

A: If the tree is healthy, don’t mess with it. At first (color difference) I thought it was growth from a rootstock. These trees are usually grown from seed or cuttings. To my knowledge rootstocks are not used.

Unlike its cousin, the Chinese pistache (Pistache chinensis), this tree (Pistache lentiscus) does not have the fall color that Chinese pistache does. It is a Mediterranean pistache, a small to medium-sized tree when pruned well.

The growth should be very flexible. It prefers growth to fill openings.

Mastic trees (smaller member of pistache trees), although moderate water users are very difficult to prune. They are better off in the background as a small or medium-sized tree or shrub and will grow slowly to 20 feet with occasional but deep watering.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to [email protected].

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