Q. I’m transitioning to a landscape with only Mojave Desert native plants.  Cacti, yucca, agave were planted early last spring and are doing well. Will this type of landscaping ever be free from irrigation like they are in the open desert? This is the Mojave Desert, unglorified, about 20 miles north of Kingman, Arizona. Notice the size of the plants. Notice their density. Notice what type of plants they are. This type of landscape requires no extra water. Is this really the type of desert landscape you want? A. That’s a tricky question because it assumes you’d be happy with this type of natural landscape. There is not much shade in the open desert. If you prefer larger plants to create shade in your landscape, then having additional plants might be worth the extra water. If you like the open desert and retreating into your house for shade then yes, you can probably achieve a landscape without extra water. It might not be very pretty, but you can do it. If not, then it will take extra water to get what you want. With some wisely placed irrigation water using a bubbler and basin, some compost at planting time, some wood chip mulch and annual applications of fertilizer and iron you can grow Crape Myrtle like this one at our research site in North Las Vegas.             Water use in landscapes is driven by the number of plants growing there, their mature size and if they are desert adapted or not. Water use increases as the number of plants increase, the mature size of these plants and if they originate from the desert or not. Wise placement of these plants can create very pleasurable outdoor living spaces. The Sonoran Desert has larger plants and more of them because it gets 250% more water than the Mojave Desert. Many people consider it a “prettier” desert because it has many more plants and the plants it has are more diverse in size, numbers and the kind growing there. More water means more plants and larger plants = prettier landscape and better soil.             For every plant that survives in the desert, perhaps 1000 or more die because they don’t get enough water or are not established in the best location for their survival. Homeowners expect every plant in their landscape to survive.             Plants make the air cooler. They transpire water from their leaves. This water loss from the leaves cools the air. And don’t forget the comfortable shade they produce as well. A beautiful desert landscape that is also functional requires water but the water needs to be put in the right locations to get the desired results. An example is this landscape finished by one of my students in my landscape design class from several years ago.             Water and comfort are trade-offs. To get the cooling shade from a tree requires extra water. If you want trees to shade your home during the summer months, then this requires water. Do you want a garden? Butterflies? Hummingbirds? These add to our quality of life. This is not a frequent occurrence without occasional extra water to support this kind of habitat. Insects like this mantid in one of my Sweet Acacia requires some refrain from applying pesticides to your landscape. Yes, those are my fingers and my friend.             Good looking plants require water unless you like the look of our native plants growing with the limited supply of water. Trees like mesquite and acacia can look a little sad growing in the open desert. But in a wash with a perennial water supply from rain runoff, they can be full and beautiful to look at. Desert plants are beautiful like this opuntia flower growing at the University demonstration and research Orchard years ago. But it requires some water.             So, I doubt if you can have a good-looking, even sparse, landscape without some additional water. But you can certainly reduce the amount of water needed in your landscape by carefully selecting the plants you grow in your landscape and supply applications of water judiciously and at the right times.

Q. I have a Contorted Jujube, which is partially self-fruitful. I acquired a Lang Jujube, which needs a pollenizer tree. I don’t really have space to plant the pollenizer tree close to it. What is the maximum distance I can plant a pollenizer tree from the other? Fairly young contorted Jujube during the summer months. It is considered partially self fruitful which means it will produce fruit without another tree for pollination but produces more if a pollenizer tree like Lang jujube is nearby. A. Jujube performs extremely well in our hot desert climate. It is also called Indian fig or Chinese date. It’s a good fruit tree selection if you like the fruit. Even if you don’t like the fruit, it’s a vigorous landscape tree if it is irrigated. Fruit of contorted Jujube in both fresh and dried forms on the same tree. Both forms are desirable depending on your own tastes.             The term “beeline” is a good one to remember. It’s more important to have the pollenizer tree in a “straight shot” from the other tree and not around a corner. Bees travel in straight lines for the most part. Contorted jujube in winter after leaf drop.             These trees are pollinated by honeybees and other insects during the early spring and summer months. So, if you don’t have pollinators actively working your landscape then fruit production will be low even if you have a pollenizer tree. Attract pollinators into the landscape by planting flowering herbs like rosemary and provide clean water they can haul back to their hive. Birdbaths work with some rocks placed in the water as landing pads for the bees.            

Q. I have a cactus garden that faces west. Every summer I hang sheets on a clothes line in front of the cactus because it always looks like they are starting to burn up from the direct sun and heat.  If I don’t protect the cactus this year, will they die? Young Joshua tree, a Yucca native to the Mojave Desert, will handle tough landscape exposures with direct desert sunlight. Photo taken at the Las Vegas Springs Preserve. A. It’s difficult to say without knowing which cacti you have. Not all cacti are the same and handle the Mojave Desert with ease. Cacti available from retailers are from a wide range of habitats. Some of these habitats are not as environmentally extreme as our own Mojave Desert.  Cactus garden at the Las Vegas Springs Preserve These cacti may show signs of stress when plunged into our Mojave Desert climate and soils. Cacti that originate from other areas may be more tender to Mojave Desert conditions. Discover which cacti you have and their place of origin. Although not a cactus, this yucca is native to the dry sand dunes of the southeastern US and is damaged by the intense sunlight of the Mojave Desert if planted in the wrong location in a landscape. Yucca is oftentimes grouped with cacti.             Of course, cacti native to the Mojave Desert have a much better chance of survival without protection than cacti imported from other deserts with a milder climate. I would recommend using these if available.  You might have to relocate some of your more temperamental cacti into a milder microclimate in your landscape. Find an exposure on the east side of the home or under some light shade. Most cacti can be relocated during the heat of the summer months.

Q. Is it possible to transplant chollas and wildflowers? I live in a subdivision that will be excavating these beautiful plants to pave streets so I was wondering if it’s possible to transplant them and if they will survive after transplanting. These “Teddy bear Cholla” can be rescued from construction sites with a little bit of advanced planning and careful management. A. Yes, it is possible to save many of them but it will be a challenge and you have to know what you’re doing. Years back I worked with a former NDOT landscape architect in preserving native plants when the road to Searchlight was widened. They attempted to rescue valuable native plants prior to construction by excavating and placing them into a nursery until they could be relocated. Smaller cacti and succulents are easier to save than the larger ones.             Contact your state’s Bureau of Land Management, Native Plants Program for information about native plant rescue. Native plants are protected and permits may be needed. NDOT Native Plant Rescue near Searchlight, NV             It’s not an easy task and requires specialized knowledge. Not all the plants will survive after being rescued. Be prepared for that. There will be some plant mortality regardless of how careful you are. Native plants have extensive roots that developed for survival under extreme desert conditions of low rainfall and high temperatures. NDOT Revegetation project near Searchlight, NV             A local landscape company called Trident Landscape Management has experience relocating native plants into residential landscapes. It’s the only one in the area that does, to my knowledge. The owner has experience and knowledge about rescuing and using native plants from our Mojave Desert and has participated in relocating them. I would recommend involving them so they have the best chances for survival. Pete Duncombe and Trident Landscape Management              Annual wildflowers are probably best saved by collecting seed. There are a few Mojave native woody plants and perennials available in local nurseries. The Nevada State Division of Forestry has a nursery in Floyd Lamb State Park that propagates and sells many native plants to the public. Consider supplementing your landscapes with these plants if they are not available through local nurseries.

Small water droplets can sometimes be found on well watered grapevines early in the season. These are not insect eggs but “grape pearls” as they are called. Q. Early in the growing season I saw small clear droplets on my grapevines. Would you happen to know what is the source of these drops?  I have had leafhopper issues in the past and I was concerned they might be insect eggs. Grapes early in the season can develop small balls of water droplets on the leaves and stems called grape pearls. They may resemble insect eggs but they are not and can be ignored. A. Not too many people see what you saw. We are too busy to notice. These droplets are tiny and difficult to see. Not all kinds of grapes seem to have them. You might see them on Concord or Thompson seedless. Nothing to worry about but it is an interesting phenomenon.             They are called “grape pearls” or “sap balls” and not related to insects or diseases. However, they do look like insect or mite eggs.  Leafhopper females lay their eggs inside the leaf veins so there are no eggs of this insect to see on the underside of leaves. Leafhoppers are tiny jumping insects found on many plants including grapes. When they feed on the leaves, the leaves develop a yellow mottled look and black spots are left behind from their feeding with heavy infestations. At this point there is nothing much to control and except for hard pesticides.             These droplets are pushed outside the leaf when the vine is full of water and experiencing rapid new growth. They are usually found on the undersides of leaves or on young stems. It reminds me of the water droplets pushed out of turfgrass through hydathodes in the spring during cool weather. There is so much water present on grass leaf blades that golf course superintendents would send someone out with a bamboo pole to “whip the greens” and remove the “dew” on the grass.             Don’t be concerned and ignore them. If your grapevines are dense, shake the vines so water drops to the ground. Otherwise they will dry normally and disappear as the daytime air gets hotter and drier.

Q. What is your opinion of pines as landscape trees in our desert climate? We have quite a few planted in our complex and our HOA is discussing whether we should get rid of them or not because of their liability and water use. Our landscaper tells us they have borers. A. I’m a little suspicious of the borer diagnosis in pine trees since it is rare for them. Have that diagnosis confirmed with a second or third opinion. Aleppo Pine gets a blight that causes browning of needles and entire branches. Probably Aleppo Pine blight             From a distance this can look like borer damage. So far no one has discovered the cause of Aleppo Pine Blight or how to control it but it’s thought to be related to irrigation and not resulting from a pathogen or borers. Aleppo Pine Blight is so common in the Las Vegas Valley that if a pine tree has brown branches, it is an Aleppo Pine, not Mondell. Eldarica or Mondell pine will get dieback in some branches as well but not as well documented as afghan (halapensis) pine blight             My opinion of pine trees used for landscaping in the desert is mixed. I don’t think large pine trees should be planted here but I do understand their light shade value once they have become established and mature. What makes me hesitate is their removal I’m not sure if the shade they produce is worth the extensive deep watering needed to keep them healthy and upright against strong winds. In some lower elevations in the Valley, these large pine trees with extensive roots may have tapped into shallow groundwater which could help with irrigation and staying stable. Japanese black pine has a distinctive look that attracts many landscape designers and architects. But in my opinion it is not a good choice for desert landscapes because of it doesn’t seem to survive to maturity in our hot desert.             Removing existing, mature pine trees from the property will increase the resident’s electrical costs used for cooling during the summer months. I would recommend that you transition your landscape to smaller, desert adapted trees that shade the south and west walls of your buildings and then possible pine removal. Once established, their shade will substitute for the pine trees and help reduce residential energy consumption. Pine trees receiving adequate amounts of water develop a full canopy of needles and demonstrate good growth. But large mature trees need lots of water to stay healthy and deep irrigations to develop deep roots to withstand strong wind.             It would be far better to plant smaller pines such as pinion and Italian stone pine if a pine tree is desired. Japanese black pine is sometimes recommended but look around. Do you see any older Japanese black pine in the valley? Many have been planted here. It doesn’t survive in the desert for any length of time so I would discourage planting Japanese black pine here.

Viragrow: How to Make and Use Compost Tea: Spraying compost tea will deliver plant nutrients to the plant to keep it healthy, promote growth and protect it from diseases by applying &…

This podcast will explain what a jar test is and how to perform one on your landscape soil.  Using a jar test will give a name to your soil that’s determined because of its texture, that is, it’s percentages of sand, silt and clay. These percentages will help you understand how to irrigate plants growing in them as well is fertilize them.

A jar test is a relatively simple method for determining the soil texture of your soil. Why should you be interested in the soil texture of your soil? Because knowing the percentages of sand, silt and clay in your soil, or in other words it’s texture, you can make some educated guesses about how much to water, when to water, how much to fertilize and when to fertilize. It costs you nothing except the time and materials you are willing to commit to it. What You Will Need You will need a clear quart jar such as a mason jar used for canning, a lid for it so that you can shake it, 1 teaspoon of liquid dish detergent, tap water and a composite soil sample from your yard. Taking a Soil Sample from Your Yard You will be taking a “composite” soil sample from your yard. This means you will collect soil samples from several locations in your landscape. Think about how deep soil roots will need to grow. Trees and shrub roots may grow 24 to 18 inches deep. Small shrubs 12 inches deep. Vegetable gardens, lawns and annual flowers only 6 to 8 inches deep. Blindly select four or five locations in your landscape. These should be random locations and don’t select them because they look terribly bad or good. Use a shovel and a 5 gallon clean bucket to collect your soil samples. Collect the soil from the surface and all the way down to the depth you think your plant roots will grow. The sample should include equal amounts from the surface all through the root zone depth of the soil. Mix these samples together thoroughly. You now have a composite soil sample from your landscape. Take 2 cups of soil from the bucket to use in the jar test. Soil Is Composed of Sand, Silt and Clay But these mineral components are all mixed together in your soil. The jar test separates out these three components and by measuring them in the jar, you can determine the percentages of each in your soil. Sand. The largest size to particle in the soil. If we were to expand its size to the size of the White House, the silt particle would be the size of a limousine parked in front of the White House and the clay particle would be about the size of an orange sitting on the seat of the limousine parked in front of the White House. So it’s easy to see these particles are vastly different in size. The Jar Test When the jar full of water and soil is shaken, these particles settle at different rates of speed; the sand particles settle quickly because they are the largest  particles. Silt particles settle out next because they are smaller than the sand particles but larger than the clay particles. The clay particles settle last and may take many hours or even days to settle. Your soil has settled into layers of different sized particles which oftentimes have different colors. The soil in the jar has finished settling out when the water above the soil is clear. Jar test performed on a landscape soil and showing the separation of particles because of their size; sand is on the bottom, silt is in the middle and Clay is on the top. The water was clear when it was added but the organic matter in the soil caused the water to change color. Separation all the soil particles due to settling through the water. There is a difference in sizes of the particles and a slight color change in the layers that indicate their separation. Determining Soil Texture You must determine the percentages of sand (bottom layer), silt (middle layer) and clay (top layer) against the total soil volume that settled in the jar. 1. Measure the total depth of the soil in the jar. In this case, the total depth of the soil was 2 1/8 inch. 2. Calculate % of sand, silt and clay. Dividing the size of each layer by the total soil measurement approximately: 52% Sand 33% Silt 15% Clay The Soil Textural Triangle The soil textural triangle is a measurement of the percentage of sand silt and clay. These percentages determine the textural name the soil is given. Our soil has 52% Sand, 33 % silt and less than18%Clay. We will name this soil a LOAM, but nearly a Sandy Loam. Irrigating This Soil This soil is classified as a loam but may have some characteristics similar to a Sandy loam. We can assume that 1 inch of water applied to the soil will drain to about 10 inches deep. How Deeply 1 Inch of Water Penetrates in Soils Fertilizing This Soil Sand does not hold fertilizers or water well. Both fertilizers and water drain through sand easily. Clay holds fertilizer and water extremely well. As the clay content of a soil increases, it holds more water and fertilizer. Silt is intermediate in how it holds water and fertilizer. Since our soil is dominated by sand we should fertilize it more often than clay soils and with smaller amounts of fertilizer each time. In extremely sandy soils we might water daily during the summer months and fertilize every 4 to 6 weeks with small amounts of fertilizer each time. In soils that contain a lot of clay we might water once a week in the summer or longer. Perhaps one or two fertilizer applications would be enough for most plants. Our soil is dominated by sand but it does have clay and silt in it. This means water drainage should be good and it should hold a small amount of water and fertilizer each time they are applied. Water intermediate between sand and clay. Fertilize intermediate between sand and clay.

Today I will be discussing why non-desert plants start to yellow in a few years after planting, some of the horrible pruning jobs done by landscapers and how it destroys these plants. I will also talk about transplanting Sago Palm, also called cycad, and whether to remove the fronds or not. Finally I’ll be discussing how to properly transplant existing rosemary from the landscape into containers. Join me in today’s Desert Horticulture.