Weeds Number One Pest Problem

Common bermudagrass is probably the number one weed to control in states below the Mason Dixon line. It creeps along underground on rhizomes and aboveground on stolons. It's perennial. Once it gets established it is difficult to control. Or is it?

Pests are not just insects. Pests include insects, diseases and weeds, not just insects. Weed control is the number one pest problem for farmers. Or for anyone with a landscape.  More money is spent on controlling weeds than controlling or preventing insects and diseases combined. Once weeds are entrenched, either annuals by seed or perennials by stolons/rhizomes, they are more difficult to control.

Roundup is the number one weed killer sold. It was made for controlling grasses but it will kill many different kinds of plants so is considered a post emergent, non selective systemic weed killer. But it moves systemically maybe about 12 inches from where it was applied to plants.

Farmers use mostly cultivation and weed control chemicals. Basically, weed control chemicals save farmers money they would otherwise spend on fuel and labor. Most of the time, homeowners are better off controlling weeds using cultivation. Oftentimes this is simply using a hoe. Make your landscape weed free without chemicals by hoeing for 20 minutes or less, consistently, once a week.

The Hula hoe or stirrup hoe is my favorite hoe for controlling weeds in many different spots. To be effective, it must be used weekly (like many organic pest control products) during the growing season or when the problem persists. 

To get good control, stay on top of weeds and control them as soon as they start growing. That means getting rid of weeds weekly, very soon after they are seen. Weeds are not like most insects or diseases; when the weather changes their populations increase or decrease. When temperatures get warmer, summer weeds grow faster and stronger.

To control weeds in bare soil, not covered by a surface mulch, either weed control chemicals or weeders like hoes or flame weeders are needed. Weeding of bare soil is weekly during the growing season and to keep weeds in check.

Weeds love to invade disturbed soils. That’s why during the first few months in new landscapes many weeds grow near plants getting water, weed barriers or not. That’s normal.

Its normal to see weeds after a landscape or lawn is first planted. 

Get out your hoe. The first weeds to grow are annual weeds. They grow quickly from seed and try to cover as much soil as possible. Once they are removed when young, there are gone forever. All annual weeds come from seed whether they appear in the spring (summer annual weeds) or fall (winter annual weeds).

Wild mustard is a winter annual weed; the seed germinates in the fall, the weed grows during the winter or early spring and then flowers and produces seed in the spring ready for next fall.

Crabgrass. Summer annual. Fast germination. Likes open areas. Doesn't like to compete. Similar to all annual weeds, doesn't like mulch. Seed germinates in the spring each year. Easy to hoe or burn. Easy to discourage with mulch.

When preparing the soil for a garden, the first plants seen are annual weeds, usually within one to three days after cultivating and planting just before vegetables emerge from seed. In the spring this is spurge (wet areas), crabgrass, goosegrass. Russian thistle. chickweed. Most of their energy forces new top growth of these weeds quickly. They want to grow quickly, become large and cover as much of the soil as possible and of course flower and seed. This is how they spread. These weeds are called “invaders”. You can use weed barriers, 3 to 4 inches of mulch on the soil surface, pre-emergent weed killers or you can use a hoe or fire weeder. Your choice. Hoes are fast and easy when you do it weekly.

Weed barriers are woven or spun textiles (fabrics) that allow air and water through but not most annual weeds.

Privacy Hedges in the Middle of Nowhere - Caution: Abuse

Q. What can I use for a privacy hedge that will be less than 10 feet tall?

Probably the most mispruned plant in the Las Vegas Valley. I looked through about 20 pictures of Texas Ranger I had but they were all pruned! But these are its flowers.

A. ‘Green Cloud’ or ‘Gray Cloud’ varieties of Texas ranger, a.k.a. Texas sage, will grow to that height with irrigation, keep their leaves (if it’s a warm winter) and become denser as they are hedge pruned. Plant them 3 to 4 feet apart when growing them for a privacy hedge, mix compost into their backfill when planting, and water the heck out of them the first couple of days. They can handle the heat and drought when not surrounded by other plants.

This is a horrible picture of it because it has been pruned by mindless maintenance companies but Texas ranger or Texas sage comes in different varieties. The first ones to come out were the Cloud versions, Green Cloud and Grey Cloud because of their leaf color. They are full sized at about 8 feet tall. They stay evergreen through the winter if it doesn't get too cold. There are other varieties that are shorter like 'Compacta' and 'Bertstar Dwarf'.

Texas rangers are native to the Chihuahuan desert of the US and Mexico. After they are established, they will not require frequent irrigations unless you want them to grow rapidly. But they will require deep irrigations if you want their roots to grow deeply, become more tolerant of hot weather and drought.

Dr. Devitt and I were walking to lunch when we saw this. Two mistakes made by maintenance companies when pruning these plants include pruning at the wrong time of year (above) and hedging them repeatedly when they are not in a hedge.

These medium sized shrubs handle either rock or woodchip mulch. Lightly fertilize them in the spring with a second application of high nitrogen fertilizer (think ammonium sulfate, 21-0-0) in mid to late November and watering through the winter helps keep them evergreen through the coldest winter.

This is what happens to Texas ranger when it is attacked by a hedge shears over and over in about five to eight years. DONT PRUNE THEM WITH A HEDGE SHEARS IF NOT IN A HEDGE!!!!!

Are Bottle Trees Really Desert Trees?

Q. Ten bottle trees planted last year thrived but then suddenly lost all their leaves at the very top during the wind. The trees are watered with drip twice a day, three times a week for the past month. The rest of the trees and the leaves look healthy. My landscaper suggested that the wind stripped the leaves. I have doubts since my neighbors' bottle trees of the same age look perfectly healthy.

Bottle trees do well in Las Vegas but are very large and not true desert (xeric) trees. These trees originate near waterways in Australia. And at 60 foot heights there is no way it can be called ":Low water use". Maybe for a tree that is 60 feet tall it can be called "low in its water use" but it is not a low water use tree.

A. I like to follow the KISS principles and get these possibilities out of the way before I jump to unusual solutions like strong wind. I suspect this problem may be associated with their watering and not necessarily the wind. Trees may lose their leaves at the top either from lack of water or watering too much. Both cause leaves to loosen from the branches and the wind just blows them way. By the way, a quick google tells me bottle trees get 60 feet tall with irrigation; big trees as they get older.

Many bottle trees are used in lawns. They are mesic so that should give them enough water provided the soil drains water.

            Irrigations applied two or three times per week in late April and early May would be about right for established trees provided they are given enough and it is applied to a large area under the canopy. This means the amount of water should not be measured in minutes but in gallons. The number of emitters and their spacing is important information to tell me because these are responsible the amount they apply and for distributing the water under the tree canopy.

As long as it is surrounded with other mesic plant getting water it is fine in a desert (rock) landscape.

            Trees planted from 15-gallon containers should get at least 8 to 10 gallons of water when first irrigated and probably double that the second or third year as the roots explore the surrounding soil and the tree gets larger and more established. Two or three drip emitters placed 12 inches from the trunk are all that is necessary the first year after planting.

As long as bottle trees get enough water and it is applied deep enough and not too often, they will grow well. The biggest problem is not getting enough water when it is watered.

But by the second or third year after planting, the trees need more drip emitters further from the trunk. Doubling the number of emitters and placing them further away from the trunk accomplishes this without changing the number of minutes.

When bottle trees are surrounded by rock, or at least on one side, they may not get enough water.

With a thin piece of 4-foot long rebar, make sure the water is applied deep enough by pushing it into the soil in several places immediately after an irrigation. The soil around bottle trees when young should be wet to about 24 inches deep immediately after an irrigation and 36 inches deep when they get bigger.

Containers Used in Single Valve Landscapes Drive the Irrigation Cycles

Q. We have a single zone (one valve) irrigation system in our yard with about 50 various plants. Plants include two mature olive trees. citrus, a dozen roses, flowerpots, and various bushes and cacti. We water the cacti by hand. We automatically water once a day, deeply, for about 20 minutes. Some friends of ours water three times a day and my son waters twice a day with no problems. Please comment.

Plants grown in containers in a landscape determine how frequently everything else on the same valve is watered. It is best that plants grown in containers are on a separate valve from plants grown in the ground.

A. The “flowerpot plants” determine how often a one valve irrigation system is turned on; its frequency. The plants in the flowerpots control when water is turned on or they suffer, and we see it. The remaining plants adjust to whatever daily watering schedule they are given. You are satisfied with this watering schedule. Everything looks good. How about your plants in the long run?

Container growing has alot of advantages but these plants must be watered often compared to plants grown in the ground.

            Watering in the desert is the “life blood” of a landscape. Plant roots grow best where there is the ideal mixture of water and air. A balance must exist between both, but not too much of either one if the plant is to be healthy and survive. Watering too often, or poor drainage, and the roots drown. Skipping a day when its hot, the plants suffer from drought.

            Watering daily encourages the roots of plants to grow near the soil surface. That’s where this ideal mix happens. Watering daily may be fine for small plants with shallow roots, but not for deep rooted trees like your olives or citrus. The larger plants prefer a lot of water applied at once (slowly or held in a reservoir around the tree) then no more applied water until half of that water is used. This irrigation strategy encourages deeper tree rooting, more tolerance to hot weather and better resistance to strong winds.

Two thoughts here. A container inside a container shades the interior one making the soil less hot in the summer. Wooden containers protect the soil from overheating better than clay pots. 

            So ideally for the plants, more irrigation valves are needed to encourage the deeper rooting of trees and shrubs. But if you are happy with how the plants look, satisfied with your water bill, want to use only one valve, and don’t care about tree health and longevity, then watering them once, twice or three times daily will work.

One irrigation valve and watering daily will work for watering an entire yard but it is not the best for the plants. 

If you haven’t done it, cover the soil with a layer of woodchip mulch to control weeds and conserve water. I have found that a layer of woodchips in the orchard allows one more day without watering as often in the summer months. As woodchips rot, roots of large trees have a bigger area to find places to grow. The olive trees can tolerate rock mulch, but woodchips for the citrus and roses works best in the long term.

Use Xeric Plants, Not Many and Select Small Ones to Save Water

The mature size of trees, shrubs, and other plants, how many there are, and their origin determines the amount of water required to support your desert landscape. Once a landscape design is finished, the amount of water it needs is fixed. It cannot be changed without consequences. It is set. You won’t be able to change the amount it needs, by much, without removing plants or replacing them with others.

Count the number of plants used, their size at maturity and the kinds of plants and their water use and the amount of water needed in a landscape is a done deal.

Massive trees like Aleppo pine, poplars and cottonwoods, and lacebark elm require deep irrigations and more water; water should be applied to wet the soil 3 feet deep or more for large trees; medium-sized trees like chitalpa, ash, and African sumac should be watered 24 inches deep, and small trees like desert willow, Texas mountain laurel and California redbud 18 inches deep. Their depth of rooting affects their health and resistance to heat damage. The same goes for shrubs of a similar size.

The only way to get roots of plants deep is to water them less often. That must be done with an irrigation valve.

As the number of plants used in the landscape increases, the more water is needed. Maybe not in the beginning when they are cute and small but when they get bigger. Also, the amount of water they need is not necessarily additive because planting them close together can affect each other’s water use. In other words, two ash trees planted close together affects the sunlight, wind, irrigation and other things that impact their individual water use.

Growing trees that want to have deep roots in a lawn that must be watered daily in the summer forces trees like this ash to grow roots near the soil surface to get air. Deep soil in lawns doesn't have any.

The “type” of trees, whether they are mesic or xeric, also affect how they respond to applied water. Mesic trees and plants originate from wet climates (think oleander, palms, iris). These plants don’t do as well when water is in short supply. They cannot grow and leaf out quickly after a drought as xeric trees and shrubs can (think acacia, Texas mountain laurel, penstemon). Xeric plants have “coping mechanisms” that handle water shortages (like shedding leaves or slowing growth).

Growing desert plants with other desert plants (xeric) allows you to use a similar watering schedule...less often but lots when they do get water. That's what irrigation valves do. They turn water on and off. This allows for different irrigation frequencies.

Xeric plants can be coaxed into using less water and then respond quickly with strong growth and increased density when water is available. But many xeric plants are sensitive to heavy daily waterings, particularly during high temperatures. But xeric plants offer the best opportunities for water savings. Most water savings with xeric plants happens because of less frequent watering rather than the amount of water applied.

Sweet acacia can be watered less often than mesic trees, thus saving water. How do I know when to water this tree? When it is not as dense as it was when earlier in the year. It needs water. About a week after an irrigation the leaves create dense shade again.

You can have the best irrigation system and plants in the world, but if you apply the water wrong it still results in water waste.

Minimize Water Use and Increase Comfort in Desert Landscapes

Minimize the total number of big plants in a landscape

This tree is out of scale with the house. It doesn't need to be that big. It only needs to shade the walls and windows. The bigger the tree, the more water it uses.

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 sized 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

Create sitting areas with shade from plants or nonplants. Nonplants don't use water.

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 man-made 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?

Concrete and steel structures are more durable 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.

Bubbler and basin irrigation can be just as efficient and easier to install for large trees as drip. Just keep the basins repaired and enlarged as the trees grow.

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.

Bamboo Can Be Pruned Near the Soil to Get it Green Again

Q. Do you have any advice on what I can do to green up bamboo planted in rock mulch and damaged from winter cold? Give them iron perhaps?

Bamboo can be sensitive to winter cold temps that we sometimes get in Las Vegas during the winter.
The most common types of bamboo used in colder climates are the "running" types of bamboo that send out runners...rhizomes...long distances from the plant and pop up where there is water available. The "clumping" types of bamboo are usually more sensitive to cold temps than "running" types.

A. There are three types of “bamboo” used for landscaping in Las Vegas. One type is a true bamboo that can sucker from its base (clumping) and increase its girth with short rhizomes.

A second type of true bamboo sends runners (rhizomes) longer distances underground to new locations where there is water. These are called “running” types of bamboo.

A third type is not a bamboo it all but called “heavenly bamboo” or Nandina. This type of plant also clusters from its base, like a clumping bamboo.

Even though they are called "Heavenly Bamboo" they are not really bamboo. They are in a genus called Nandina and sometimes called that.

Fortunately, all three can be “cleaned up” the same way; prune them back to within one or 2 inches of soil to force them to re-sucker from the base. Since the first two plants are “grasses”, any fertilizer high in nitrogen will force the suckers to grow green again. Nandina is different. It is not considered a “grass” and should be fertilized with an all-purpose tree and shrub fertilizer.

Nandina is native to Japan and China and does clump due to its rhizomes. But it can handle cold temperatures better than true bamboo. But it must be planted in amended soil and not rock to look good. Prune several big stems back close to the ground and add compost and woodchips and see it turn green again.

Apply this fertilizer before cutting them back. Then prune them, give them water, and watch them grow! All three of these plants will benefit from an iron application.

Sulfur Lowers Soil Alkalinity and Can Impact Plant Nutrients Like Iron

Q. I put sulfur in the ground around my yellow bells and the leaf edges which were browning cleared up. Why isn't sulfur mentioned more often?

When sulfur granules are spread on the top of dry soil it doesn't do much good. They don't dissolve and lower the soil alkalinity (measured as soil pH).

A. Sulfur is not usually mentioned much but it can be effective in soils for two reasons; it is a plant nutrient needed in large amounts by all plants and it can lower the alkalinity (soil pH) of soils under the right conditions. I dont mention it much because it needs wet soil and warm soil temperatures to work and can be a problem if the wrong kind of sulfur is used. Use sulfur, not a sulfate.

I dont want people applying a sulfate fertilizer thinking its going to work because it has sulfur in it. Ammonium sulfate is an acid type fertilizer but it is because of the ammonium in it, not the sulfur. This sulfur is reduced to its final state...sulfate, SO4...and cannot acidify the soil. Tricky thing about chemistry.

            Sulfur is needed by plants in large amounts. It is a plant nutrient. Most of our soils have enough sulfur in them from the parent rocks that adding it is not that important. If you are curious that your soil may not contain enough sulfur, send a sample to a soil testing laboratory, and find out. They need about 2 cups of soil to analyze it. Another option is to add sulfur to the soil (as you did) and look for plant improvement (which you also did).

A sulfur burner like this one burns sulfur and injects the gas from it into the irrigation system to lower the water pH (alkalinity).

            When pure sulfur dissolves in the soil it makes sulfuric acid. This acid helps to lower our soil alkalinity. This lowering of soil alkalinity is measured on the pH scale. This will not happen when using fertilizers that contain only sulfates. A lowering of alkalinity makes plant nutrients like iron, manganese, and zinc, needed in smaller amounts by plants, easily available.

 

Sulfur is available as water dispersible granules or in powder. This dissolved quicker than granules but still needs water to make it work.

            The problem with adding sulfur to soils is its granular size, the moisture needed to make sulfuric acid and warm soil temperatures. Mixing small or pulverized pure sulfur granules or sulfur powder into wet soil during the summer months has the best chance of reducing alkalinity in soil and getting good plant results quickly.

Fruit Crops Reduced This Year on Some Trees

Q. Have you seen a reduction in fruit of plums, and pluots this year? My trees are 3 to 5 years old, and I did not see many flowers on them this spring. Not a lack of pollination, but a lack of flowers! This year the trees have anywhere from 5 to 20 fruit and last year they were easily over 100.

Apricots, peaches and plums had a poor fruit set on some trees. Watch for freezing temps in the spring when they are flowering and learn about alternate bearing fruit trees.

A. Yes, I have seen a reduction in the amount of fruit produced this year in some varieties and types of fruit trees. If little fruit is produced but the tree flowered, it can be for many different reasons such as a quick freeze before sunrise when the tree is flowering, wind, not enough pollinators like honeybees and others.

But you nailed it. The first question to ask yourself when there’s no fruit is, “Did it flower?” You told me your trees didn’t flower. Without flowering it’s impossible for a fruit tree to produce fruit. Good job!

Apricot flowers are seen on short shoots called spurs. Dont break them or they will never grow back. No flowers produced, then no fruit either.

A lack of flowering this year, yet the trees flowered in previous years, is very telling. It is either something you did that contributed to its lack of flowering or something inherent to those varieties of fruit trees. The three most common reasons for growth and no flowers are heavy pruning, applying too much high nitrogen fertilizer and, common to some types of fruit and nut trees, is a trait called “alternate or biennial bearing”. Non-flower production can be for several reasons in combination.

Reducing the size of a fruit tree by pruning can shove it into a “younger” stage of development, particularly when they’re only a few years old. Some fruit trees are more finicky about this than others. These trees like to maintain a specific size relationship between their root system and the spread of their limbs or shoots. This is called the trees “root to shoot ratio”. When the top of the tree is pruned, the tree may favor the ratio of roots to shoots it had before pruning. When the top is pruned back, the tree throws all its energy into new growth at the expense of flowering. Luckily, this interruption only lasts one season.

Some trees are more sensitive to pruning and producing fruit the next year than others. This Hachiya persimmon wouldnt produce fruit the following year after severe pruning. It did fruit the year after.

The same interruption happens when high nitrogen fertilizers (first number on the fertilizer bag) or excessive amounts of fertilizer are applied to fruit trees. A telltale clue is its rapid spring growth and its dark green leaves. I like to see about 18 to 24 inches of new growth on young trees. I know we want trees to get big fast but be careful with high nitrogen fertilizers. Both visual clues (lots of growth and dark green leaves) are signs the tree received too much nitrogen and its fertilizer. Apply a lesser amount of fertilizer (or even consider no fertilizer that year) that best matches its need for both growth and fruit production.

When some plants are too young they will not produce flowers or fruit. Other reasons for no fruit can be applying high nitrogen fertilizers excessively, lack of bees, freezing temps when they are flowering and others.

The third reason may be a fruit and nut tree trait called “alternate or biennial bearing”. Some types of fruit and nut trees can produce fruit heavily one year and then fruit lightly the next. These trees are susceptible to cycles of abundant fruit followed by a trickle of fruit the following year. Trees that exhibit this kind of trait should be thinned of fruit a lot during years of high production. Heavy thinning in abundant years reduces the trait of “alternate bearing”.

Bay Laurel is a Smallish Tree and Doesn't Like it When Its Very Hot

Q. My bay leaf bush developed lots of brown leaves.  The plant is in our courtyard facing north.  There are 3 more of these plants in this courtyard not affected with this problem.  A few gardenias next to this plant have the same problem.  What is causing it and what is the remedy?

Bay leaves and gardenia leaves both brown from summer heat. Both plants prefer to grow in a soil amended with compost and woodchips.

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.

Bay laurel is a small tree, not really a bush unless you prune it that way. It will get 20 to 30 feet tall and does not particularly like very hot temperatures. This small tree is on the north side of this home. It is a Mediterranean plant that can struggle with very high temperatures. It will not like it planted alone.

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 Emitters

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.

Amend the Soil and Cover it With Woodchips

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. Woodchips that will rot for future soil improvement keeps the soil healthy if applied on top of the soil under these plants.

Wild Asparagus Plants in the Desert

Q. My wife and I were out hiking and found some wild asparagus growing in the desert, not close to any water. How did it get in these remote places?

"Wild" asparagus can be from an old abandoned homestead or seeds dropped by animals. The size and number of the plants in this Mojave Desert location tells me there is water in this location. If seed can get established and find subsurface water that these plants found then it will survive.

A. Asparagus is thought to be Mediterranean in origin. Like many non-desert plants, it grows best with access to water. When “wild asparagus” is found in the desert it is usually found near irrigation ditches or other “oasis” places that can supply it with water. Sometimes it is found abandoned by homesteaders or seed was dropped by animals, particularly birds. In any case, to survive in the desert it had to have access to water from somewhere.

            When asparagus spears are grown after harvesting, they produce flowers and then berries and seed. Flowering starts when the spears fern out at about 3 to 4-foot heights and eventually bush to about five or 6 feet tall. Asparagus, just like mulberries and ash trees, are dioecious, meaning there are boy and girl plants separated from each other.

Asparagus flowers and then fruits. There are male plants and female plants separately. This seed inside these red berries comes the female plants. Once fresh, the seed easily germinates.

The best spear producers are the male plants. All-male plants are favored for spear production. The best seed producers are female plants. Female plants are not as popular as male plants because their potential growth is used in seed production. Just like the trees mentioned, there is a 50-50 mix of boy and girl plants after germination from seed. Asparagus seed is not difficult to germinate. When the seed is soaked in water for a couple of hours and planted, it germinates easily. 

How asparagus grew there is a good question. But I’m guessing thousands of seed didn’t make it while this one did, if dropped there by animals.

Upright Junipers a Substitute for Very Large Italian Cypress

 

Italian cypress will grow to 40 feet and taller. Great for big buildings but not for homes. Consider smaller evergreen trees (conifers) like some of the upright junipers. Choose heat tolerant types if you do like 'Spartan'.

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 foot 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 cypress’ like 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. But its size can be controlled with irrigations.

Utah juniper is a Nevada native tree that does not use much water whose growth can be controlled with irrigation. They can get to 40 feet, like Italian cypress if watered with abandon.

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.

Water Bill too High? Keep Good Trees and Get Rid of the Rest

 

Any plants that get bigger will shade and kill each other as they get larger. You want to reduce watering? Keep the trees that provide good and remove the rest. Dont forget this requires less water. Manage it.

Q. I have 13 each, 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 70-80% 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.

Force Plant Roots Deep When Its Cool

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 “remainers” will receive more wind and have less support.

Drip tubing has drip emitters embedded into its walls. Drip emitters will come in different sizes but not the drip emitters embedded into the walls of drip tubing. They are all the same, perfect when plants need all the same amount of water.

Consider Drip Tubing

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 applied more deeply from drip irrigation. In a conversion to drip irrigation the time increases from 12 to 15 minutes to one or 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.

Do It in the Fall

The best time of year to do this is when 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.

How to Reduce Landscape Irrigation

 

Make every plant count! Each plant uses water. In the desert, water is precious. Chinese pistache at the Springs Preserve.

 

Make Each Plant Individual and Important!

Minimize the number of big plants in a 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. As they get bigger, they require more water applied further from the plant. Large mature sized plants require more and more water as they grow bigger and bigger.

Every plant needs water. As plants get bigger, they need more water. Can you accomplish the same purpose by using fewer plants?

Do Three Things

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 from a small deciduous tree falling on the south windows and walls of the home can reduce energy costs for air conditioning by 20 to 25%.

Shade South and West Sides

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.

Sometimes being creative in your design can save water. Here a trellised plant provides shade on the opening of a door.

Make Shade from Nonplants

Shade doesn’t have to come from plants. Shade also comes from man-made 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?

An arbor covered with a vine uses less water than a tree.

Drip Irrigation May Not Be for YOU

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.

Basin irrigation can be just as efficient as drip irrigation. Keep the floor of the basins flat and the sides in repair.

Take Charge of Watering!

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.

Take charge of your irrigation and plant growth and you can have what you want and afford it.