Gallons per Hour from Drip Tubing

Q. How many gallons of water can be used from half inch drip tubing without running into problems? ¾ inch?

The maximum water flow at 5 ft./s in half inch drip tubing is about 240 gallons per hour (gph) while three-quarter inch drip tubing will carry about 320 gallons per hour (gph). Of course the pressure is anywhere from 25 to 35 psi. 

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 half inch or three-quarter 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.

Drip tubing has emitters built into the walls of either half inch or three-quarter inch plastic tubes. All the emitters are the same size and space the same distance apart. Emitters can range from 12 inches to several feet apart. If the correct pressure is applied to the water, a consistent amount of water comes out of these emitters. Blank drip tubing on the other hand has no emitters built into the sidewalls. It's major purpose is the transport of water from one place to another.

            In 100 feet of tubing, the half inch blank tubing (drip and blank) can handle about 250 gallons in one hour. The three-quarter inch tubing can carry more water than half inch tubing. It can handle about 480 gallons of water, 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.

Another purpose of blank tubing is to put drip emitters into it. This can be done directly, as in the picture, or they can be connected to the blank tubing by quarter inch quarter inch blank tubing.

            Individual drip emitters are usually inserted into “blank tubing”. These inserts either are directly inserted into the blank tubing or connected to it with quarter 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 half inch tubing!). Buy fittings from the same manufacturer as the tubing used.

These are accessories called "barbed fittings". These fittings fit inside the tubing and keep tubing from coming apart when normal drip irrigation pressures from pressure regulators are used.

Growing Cherries in Las Vegas

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 will try cherry pits. Is this possible to get them to sprout and what is the best way to do it?

Growing cherries in Las Vegas was disappointing unless you have a high humidity backyard. Cherry pollination may be susceptible to a low humidity.

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 which 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.

'Hachiya' persimmon produces fruit that is probably some of the best I have tasted in the world including the sweet flavor of the Philippine mango variety called 'Guimaras'. But that variety of persimmon may be susceptible to the low humidity of the desert.

            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 seed, 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 one-gallon container or smaller peat pot first before moving it to a larger container. Larger containers are okay to use when the plant is bigger.

This is the sour cherry called 'Montmorency' growing in Las Vegas.

            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) 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.

Green or immature 'Hachiya' persimmon in Las Vegas.

            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”.

Redoing Landscapes with "Water Smart" Plants

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.

Texas rangers, aka barometer plant, is native to the Chihuahuan desert of west Texas, New Mexico and the state of Chihuahua in Mexico. It produces flowers on new growth. In the desert of Chihuahua it flowers after new growth from rain, hence aka the barometer plant.

Where to Look for Plants

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 canopies, “water smart” trees can survive with about 2 feet of water applied under their canopy. 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.

Water Smart pdf list

Las Vegas landscape plant searchable database

 Simply substituting lower water use trees and shrubs will not change their need for water. Plant irrigation must be managed.

Most cacti can be planted in full sun.

This mountainous cactus is native to the higher elevations of the Argentinian desert called Monte. It does not have as much intense sunlight as the Mojave Desert. This cactus will survive full sun but is best grown with afternoon shade. It can handle cold (to about 20F) but not the intense sunlight of the Mojave Desert all day long. Different types of cacti have different requirements and landscape exposures.

            Still water deep and not very often. I was at a landscape where it was watered with small amounts of water every day except Sunday. All the plants used could have deep roots if they were watered differently. 

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

AMWUA plant list

            I believe the water companies want you to use a website that focuses on low water use plants appropriate for this area. Use plants from the US deserts as much as possible. 

             Remember, it is the landscape plant size and total number of plants in your landscape that determines total landscape water use. The roots of plants don't care about "shared" water. They just want enough and applied at the right time. Not little sips of water daily.

Roots Need Air

Instead of watering daily, water with more minutes (deeper) and give the plants a “rest” without water.  Increase the minutes (or the emitter size) they are watered to compensate for “rest” days without water. Do this during the heat. Make sure the plants have at least two inches of mulch on the surface of the soil. surface mulch reduces soil water lost to evaporation. This mulch will give the plants one day of “rest” (without water) between irrigations.

Peruvian apple cactus. Guess where it's from? Tropical parts of Peru, Brazil, Venezuela, and Colombia. This cactus prefers the higher humidity of the tropics but not the intense sunlight of the Mojave Desert.

How to Begin

            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.

Accentuate Places That Don't Need Water

            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). 

Use different sized rock in the landscape. Different sized rock doesn't use any water.

Wall art doesn't use any water.

            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!

Ground Squirrels Damaging Yucca? Maybe Not.

Q. I have ground squirrels that killed my agave. They dig around it, eating the roots, and finally killed it. What do I do? How should I protect it?

One of the antelope ground squirrels common in the Mojave desert.

A. The ground squirrel you're seeing is referred to as an antelope ground squirrel. They are omnivorous which means they will eat insect grubs if they find them. But when food is scarce my feeling is they will go after anything.

One of the American agave used for landscaping in Las Vegas. The rock mulch has been disturbed by these ground squirrels.

            I am guessing but I think what you're seeing is an attack first by the agave weevil in the spring with the ground squirrels digging up the grubs and eating them. In any regard, it's always best to drench the soil around these agave weevils with an insecticide when spring temperatures begin to warm up. In our climate it is normally the end of March or the first part of April. This application protects all agave. If you have agave and want to keep them, you must protect them from agave weevil in the spring. I don't know of any organic methods that have been tested that I can recommend.

Agave weevil babies (larvae) are found eating the soft and succulent tissue found at the base of leaves and the roots or crown. They attack mostly agave, laying their eggs in when spring temperatures begin to warm in the spring. This is usually around the end of March or early April in the Las Vegas climate.

            American agave is native to the desert Southwest. Irrigate them with a lot of water slowly (so the water can go deep) and then hold off watering them for at least two or three weeks during the summer. Watering infrequently, but allowing the roots to dry between irrigations, will get them growing. The plants are thought to store water in their fleshy leaves. Water them less often if you don’t want them to grow but maintain their size. In any regard, it's probably going to be best if they are watered slowly, like rainfall in the desert.

One of the many kinds of American agave with root weevil or weevils. American agave is one of the hardest hit by agave weevils.

Divide Red Yucca After Five Years in the Ground

Q. We have multiple red yuccas in our front yard. For the first time they have started turning yellow in the last few weeks.  They are on a drip irrigation system and are watered twice daily for 5 minutes each time in the early morning and late evening. Any idea what the issue could be?

This is what  your red yucca could look like if it were divided every few years so that it produces more flower stalks.

A. They are watered too often. Red yucca (Hesperaloe parviflora) is native to the desert Southwest. They can be found growing naturally in the Chihuahuan desert of western Texas, New Mexico and in the state of Chihuahua, Mexico.

Red Yucca is okay planted in rock mulch but should not be hedge pruned. Instead red yucca should be divided when flowers begin to grow from the edges. Your natural way of propagation (getting more plants and more flowers) is by digging it up in the spring or fall and separating the clumps it has formed. These clumps prevent flowering from its center.

            They don’t need water frequently but they could sure could use applications of water 12 to 18 inches deep when they do get it! Slow applications of water, deep, are ideal for drip irrigation. Applying water every three weeks or so will get them to grow larger. Applying water every eight weeks, but still deep, will sustain their size.

Producing flowers from this plant means dividing it.

            Watering frequently (once a week or less in the summer) causes desert plants to grow. They like water for growth...but not often....Irrigating them three weeks apart will get them to grow larger while watering them with the same amount of water, but less often than three weeks apart will make them keep their size. 

            Experiment with your soil. Soils are different in how they hold water. They can be watered slowly with a garden hose or connected to the irrigation system with an irrigation clock, but using the timer only when the plant needs water. The key is to experiment with you soil but do the experiments when it is cooler.

Older Agave Yellowing and Not Looking Healthy

Q. My agave is 10 years old and just isn’t looking healthy. I’m afraid of losing it and the surrounding plants. Can’t figure out if it’s too much or too little water. Your expertise would be appreciated.

Not a whole lot of information but I am guessing it's a watering issue. Agaves are usually from the desert Southwest. But it could be agave weevil that damaged the plant earlier in the year.

A. Most problems with agaves are from boring into the trunk and roots by the agave weevil and less to do with water. Eventually the immature forms of this insect tunnel into the base and trunk of susceptible plants. Look for them.

Agave weevils give birth through their eggs to destructive smaller grubs about 3/8 inch long. They infest the trunk and roots of agave and a few yucca. Look for their damage on older plants later in the year.

This is one of the many types of American agaves showing collapse of the leaves due to probably agave weevil.

All agaves should have a systemic insecticide applied by spray or soil drench in the spring, no later than March or early April. With spray insecticides it’s important to spray the lower leaves and the surrounding soil at this time. With soil drench insecticides it’s important to apply it to the soil immediately around the plant at the appropriate time. American agave, in particular, is very susceptible to this pest. Be sure the appropriate insecticide is used by reading the label.

Example of a liquid garden systemic insecticide that gives at least a couple of months control of insects (picture taken from Amazon)

            The agave weevil lays its eggs in susceptible agaves and some yucca when temperatures begin warming in the spring. These eggs are laid by the agave weevil inside the lower leaves, close to the trunk, around that time. A single application of a systemic insecticide is needed around that time. I don’t know of any proven organic methods that control this insect.

            If you are still concerned about watering and drainage, make sure that these plants are not watered daily. All perennial plants need the soil to drain away from their roots. Some plants like agave and cacti should never be planted at the bottom of a ridge. Tops are usually okay but not bottoms. Too much water accumulates in those low spots for agave. Other plants may need a continuous moist soils not most agaves and other plants that originate from the desert Southwest.

Searching My Blog

Q. I used to get your newsletter but got dropped. Would you please add my email address to your list?

The handwritten number 1 indicates the search engine,

A. I don’t maintain that newsletter list anymore but instead rely on my blog, Xtremehorticulture of the Desert. This blog consists mostly of posts generated by questions I get and printed in the newspaper. You can get the information you need (including pictures) by visiting this blog. If you sign up for this blog you will receive notices when new articles are posted.

            This blog is searchable. There is a search engine for this blog located in a long box just under the title. 

This is the title page of my blog. The search engine for this blog is located just below this picture in a long box.

Relevant posts are displayed by entering keywords in this box.

Palm Trunk Loss of Wood Growing in Lawns

Q. I live in a cold climate area in Australia. Palms are unfortunately rare in a garden in our area. But in our local park we have two big old palms. I have noticed the bases on them look a bit odd. Is this normal? Sorry, I don’t know what type it is. I have attached photos.

On trees growing with overhead irrigation typically have loss of one from their trunks at the base. This is from irrigation water constantly hitting them.

A. Usually that type of deformity (wearing of the “wood”) of palm tree trunks is caused by the irrigation sprinklers constantly hitting it. Palm trees are monocots and so their distribution of water through the trunk is different than for many other trees. Most trees rely on renewal of the water conducting tissue from a “ring” of growth (cambium) that grows just beneath the bark.

Palm trunk starting to get grotesque

            Nothing to worry about in palms. With lawn overhead irrigation, that is considered "normal" for palms. By the way, most palm trees should not be grown where there are lawns (we call these types of landscapes, “mixed landscapes”) but irrigated separately. Tree and shrub irrigation is different from lawns and they interfere with any overhead irrigation supplied to lawns.

Cross-section of a dicot trunk. The water conducting tissue is produced by the cambium which is a circle in mature dicots. If this were the trunk of a monocot like  most palms the water conducting vessels would be in bundles dispersed through the trunk.

Correction of Cycad (Sago Palm) of Yellow Fronds

Q. My sago palms (actually cycads) planted in my yard are turning yellow. Can you tell from this picture what they need?

Yellow fronds of sago palm can arise because of its planted location, poor soil used for planting, and watering.

A. You have three choices about why the fronds are yellowing: their location (landscape exposure), needed soil amendments (including fertilizers), and improper watering. It is up to you to figure which one (or several at the same time) might be responsible.

            Judging from the pushing of new growth from the plants center, I think they are getting enough water during the week. Water this plant three times a week, not more often than that. Don’t reduce the weekly amount of water it is getting!

Notice the artificial grass that was installed. Removal of a lawn and replacing it with nothing that adds to the soil can cause yellowing of fronds due to a slow decline of organic matter in the soil.

            When you are watering, apply it to a depth of 12 to 18 inches. This will mean that you need to apply in a single application anywhere from 5 to 8 gallons of water. Apply this water through three emitters, located 12 inches from its trunk, to get a good distribution of water. Don’t split the application of water in the morning and another in the afternoon. That’s silly unless you see an enormous puddle of water when you irrigate. If water puddles on the soil surface, split the application of water into two applications an hour or less apart.

Rooting depth and how deep to water varies with the size of the plant. Taller plants need deeper (and less frequent) watering.

            This plant is originally from the richer soils of northern India. It evolved with these types of soils. It doesn’t like the extremely low organics of desert soils! Iron fertilizers should be added to the soil in the early spring but now is okay to do it. Be sure to add this composted soil where the soil gets wet. If the compost you are adding comes in a bag without a description, then it is probably low in fertilizers as well. Mix in the appropriate fertilizers to the compost before mixing it with the soil.

Late in the growing season requires spraying iron on the foliage several times about a week apart to be effective.

            Make sure any surface mulch is at least two inches deep. Using mulch adds one or two days of extra water! Mulch can be crushed rock or wood chips. Wood chips are better because they decompose in wet soil adding organics to it as the wood chips decompose. Crushed rock doesn't add any organics back to the soil. You should add organics to the soil (compost) every two years if the mulch is crushed rock.

Rock surface mulch adds minerals to the soil as it breaks down, not organics.

 Plants have to handle that.

            If a lawn was removed in the past three to five years this might explain the yellowing as lawn adds “organics” back to the soil. Removing the lawn also removes the “organics” added by lawns.

Lawns add organics back to the soil from its root growth and lawn clippings left to decompose.

            I don’t think this cycad will be better in a different location’ but cycads grow best on the north and east sides of a home. They prefer to grow with morning sun and afternoon shade.

Grass Removal Mandates and Landscape Water Use

Q. Because we are an HOA, we are mandated to remove the grass surrounding our condos.  We have over 100 mature trees. What is the best irrigation to put on these trees after the grass is removed?  We want to save as many trees as possible. My particular unit had the grass removed many years ago and I have a large pine tree.  It is irrigated with drip emitters surrounding the tree about 4 feet from the trunk.  It is doing fine.

There are lots of reasons why large pine trees do well when the lawn is removed and drip irrigation is installed. Notice shrubs irrigated nearby. They need water as well and may be feeding the tree water.

A. Yes, lawns are big water users. Some types of grass (tall fescue in particular) needs daily watering during the summer and use about 7 feet of water (7 x 12 = 84 inches of water) each year to look good and lush. Bermudagrass lawns use less; about 4 and a half feet of water (54 inches) each year. Less, but still not low enough. We want to get our total landscape water use averaging around two feet of water each year. It makes sense that lawns are targeted because of their higher water use.

Newly planted Chinese pistache in a lawn. The roots of this tree will grow more shallow to accommodate the frequent lawn watering and other shallow rooted plants growing at its base.

t is not only HOAs. Any entity that has property is required to conserve water by removing lawns.  I would also include trees too large for the area and “out of scale” with the home. Just substituting lower water use plants, and finding a lower water use irrigation system alone, does not work. You will lose some trees, particularly the large ones.

Pine trees with adequate water will be full and the limbs will be growing strong.

Do you want to choose where water is applied or have someone decide for you? Lowering total landscape water use requires finding a balance between open areas that need no irrigation with areas that require irrigation. Total landscape water use is finding a suitable balance between the two. A less complicated reduction in total water use is finding a balance where water it is needed and where it is not.

Growth of pine trees comes from the ends, terminal buds. The new growth should be, in older pine trees, average about 10 to 12 inches.

Your landscape committee should be charged with identifying zero water use areas. Filling these areas may include the use of statuary, murals, paintings, gazebos, etc. They don’t need water. Start by identifying areas where loss of plants is not as important as other places. As these places eliminate the need for water, substitute statuaries, murals, paintings or gazebos that need no water but still beautify.

Landscape art (no water) should draw your attention. It can substitute for a lack of plants that need water. Landscape art can be an investment. 

Next, shade the south and west sides of buildings to prevent overheating of these units during the summer. Use deciduous trees for solar heating during the winter. Consider removing large plants on the north and east sides of buildings that have little function in heating or cooling the home. If plants remain or you find other plants, concentrate on smaller plants (less than 20 feet tall for single story homes) that use less water. Water the remaining trees and shrubs in irrigation “clusters” for ease of water delivery and finding leaks.

Even though it may be considered a desert tree, if it's not needed or the size is too large for the spot, get rid of it of make is smaller to save water.

            Water savings come from the “averaging” of water use over the property and the creation of non-irrigated “open” spaces. You can have your cake and eat it to but not everywhere! These open spaces instead may use statuaries, murals, paintings and gazebos that don’t use water.

This west side of a hospital in Parker, Arizona, shaded the windows and walls with low water use trees that don't get all that big. The rest of the landscape uses minimal water.

Where to Get Free Woodchips in Las Vegas?

Q. In one of your previous articles you mentioned free woodchips. Where do you go to get them?

Woodchips are different from bark chips. Bark chips are prettier, but they float and blow away in moderate wind. Woodchips don't do that. They don't easily blow away (I have personally seen them withstand 70 mph gusts) or float. Woodchips should be applied at least 2 - 3 inches deep to control weeds and conserve water. Woodchips rot into the soil (where its wet) and improve it by increasing its organic matter content.

A. You have to travel to North Las Vegas, but you can get a pick up load or trash bag full from the University Orchard. Call 702-257-5555 and get an update from the Master Gardeners regarding woodchip availability and what days and hours to get them. Woodchips are usually available on Tuesdays, Thursdays and Saturdays in the mornings (except holidays). Woodchips are usually available in North Las Vegas (in the Aliante area) about 100 yards east of North Decatur and Horse Drive at the Center for Urban Water Conservation.

Bark chips or bark mulch floats in water and blows in the wind. It resists soil rotting. It is inferior to woodchips (chopped up) from the entire tree.

             Woodchips are different from bark chips. Bark chips blow in the wind, resist soil decay and are water proof. Woodchips are made from grinding the entire tree so it can be taken to the dump. Yes, it includes bark woodchips but it is a smaller percentage of the chips and it is mixed together. Woodchips includes ALL of the tree ground up into woodchips, not just the bark. 

The weed in the picture is perennial nightshade and, along with bermudagrass, will grow through the woodchip mulch. Why? Because they are perennial and push through two inch mulch. Most weeds controlled by a surface mulch like woodchips are annual weeds. Most first weeds are are annuals.

             Bark woodchips are pretty. They make a prettier looking surface mulch. If you want your surface mulch to look pretty, then use a bark mulch. Or use both separated in layers. 

Bark chip (bark mulch) doesn't rot as easily as woodchips because the bark is made to be weather resistant.

            Tree woodchips are not as pretty but functional. When laid on top of the soil in a layer at least two inches thick it saves water, controls most weeds and improves the soil.

This is what can happen if mulch is not used. Annual and perennial weeds have a field day growing. No competition for sunlight, air and water! Weeds have a field day.

            Organics in our desert soil is severely lacking. To rot woodchip mulch takes water. Water and organics in the soil are linked. More water applied, more organics in the soil. Most trees and lawns require at least 2% organics in the soil. Vegetables need more, usually closer to 8% for quality vegetables. 

Map of the US soil organic matter content (scientists call it soil carbon content) https://extension.umn.edu/soil-management-and-health/soil-organic-matter-cropping-systems

How to judge if your soil has organics in it? Use the color first. If your soil is very low in organics it will be closer to light brown or even tan in color. If organics are present, desert soils become darker and start develop some structure. The higher the ‘organic content” in the soil, the darker its color. If a soil has 2% organics in it, it has a color similar coffee with a creamer in it. If it has 8% organics, it is a “chocolate brown” in color.

Mojave desert landscape soil in Las Vegas, Nevada

Visually is how to judge if organics should be applied to Mojave desert soils or not. In most Mojave desert soils, we judge a soils “organic content” from its darker color. That’s because it starts off light tan in color. If your soil has a darker color and you can make “dirt bombs”, then adding organics such as woodchips won’t help much when planting trees and shrubs. But that organic content may not be suitable for growing quality vegetables without compost added.

A method to use to judge soil organic content is the color of the soil. This is a jar test of a desert soil.