Q. I intend to remove the all rock layer around my roses and apply a 3 inch layer of quality compost, dig it in carefully, and cover it with western red cedar bark. However, the rock layer is convenient for blowing out all the leaves from other plants around my roses. How do I keep the rose area clean? Roses growing in rock will start to be “unhappy” in about three to five years. A. There is a way to make your roses happier and still leave the rock in place. I understand it was convenient before because your maintenance people would come and blow away all the debris with a power blower. With cedar bark, it will blow everywhere and make it difficult for your maintenance people to keep it clean. Bark Mulch vs Woodchips             First of all, bark mulch is not as effective as woodchips for a couple of reasons. Bark moves around in strong wind and when “blowers” are used in the landscape. Woodchips “lock” into place because of their rough edges and don’t move around even if the wind speed is 60 or 70 mph!  If wind is a problem I would not use bark mulch unless you are willing to “tidy up” afterwards. Bark mulch is very attractive in landscapes but doesn’t decompose quickly and blows with any type of wind.             Secondly, bark mulch is pretty but it doesn’t improve the soil much. Woodchips disintegrate into the soil when moisture is present. In my experience, about half of it decomposes into the soil in about three years. This disintegration supplies organic matter back to the soil quickly. Woodchips don’t do that. They resist decomposition. That’s one important reason why bark comes from the outside of the tree and wood doesn’t. Keep Your Rock Mulch             Here’s how to keep your rock mulch and make your roses happier. Rake back the rock mulch 18 – 24 inches from your roses. Apply about ½ inch of good quality compost in this new area of bare soil and lightly incorporate it. Rake the rocks back and lightly water it in. Voilà! You have now added organic matter to the soil and made the roses happier. High quality compost like Soil Pro has lots of benefits including better microorganism counts and loaded with plant nutrients.             With very coarse rock mulch you can just sprinkle the compost on top of the rock and water it in. You will see improved growth from your roses in 3 to 6 months with either method. Repeat this about every two years.  Benefits of Woodchips What the roses benefit from is the decomposing woodchips and added organics to the soil. Rock (surface) mulch lets all the organics in the soil finish decomposing and your soil slowly becomes more mineralized. The organics in the soil start dwindling. As that happens, the roots of the roses finds itself in a progressively unhappy root environment. The unhappiness of the roots show up in the leaves with them yellowing, brown edges, and generally just not very productive. Woodchip mulch is made from chipping the wood inside trees. Oftentimes the only way to get it is through “tree trimmers” like First Choice Tree Service.  Don’t Forget Iron  If you still see some leaf yellowing, apply your favorite iron chelate to the soil around them once a year in late winter (late January or February in LV). If your favorite chelate doesn’t work then use the EDDHA iron chelate available from Viragrow ($20/lb) or Amazon or anyplace that sells it.  EDDHA iron chelate is effective in whatever soil you have. During mid to late summer or later you will have to spray it on the leaves.  Viragrow is cheaper! Iron chelates for leaf spraying is applied when most of the rose growth is finished for the season, like mid to late summer.

Q. This tree is approximately 15 years old. This house sat empty from 2004 until January 2020 when we purchased it. The house faces North and this tree receives full sun most days. Water during the 12 years was at best sporadic to none. I removed 95% of the plants and trees and just completed a comprehensive landscaping project. This tree was shaped and pruned by a licensed arborist. It suckers like crazy. It needs another round of sucker removal. I was not familiar with this specie and of course we moved in January and the tree had dropped all its leaves. The neighbors convinced me not to remove this tree because it was so beautiful in the summer, lots of flowers and beautiful leaves. I said yes because I did like the shape of it. What a mistake. The constant leaf and flower drop is terrible and a real challenge to pickup. In fact I made two mistakes, I planted another 24″ box size from a local nursery . It is doing the same thing. I do not use my drip system and deep water the tree every 3 weeks during the summer months. I water from the trunk out 7 feet around the entire tree. I have a lot of large surface roots due to the lack of water. I am applying about 75-100 gallons per application. The leaves are full and supple, not dry and then boom they turn yellow, get this brown scalding and dry up and drop. I have been researching and have not found a conclusive reason for this. The agricultural extension at NMSU wrote its not a matter of disease but rather a cultural practice. Soil may be to alkaline and getting to much water. According to Dr. Natalie Goldberg, NMSU Extension Plant Pathologists, “No plant pathogenic microorganism’s were isolated from submitted samples. The symptoms occur on trees well watered as well as those that receive little water.” The leaf drop starts when temperatures increase. Can you bring me up to date with your latest information about this type of leaf drop. If I can’t correct, both trees are headed for the cemetery. A. I did print nearly everything this homeowner told me he did for this tree which was a lot. I abbreviated what he told me for the newspaper. It does not sound like a lack of water. Older picture of Chitalpa in Las Vegas.             Chitalpa is regarded as somewhat drought tolerant which means you should be able to water it less often than, let’s say, a purple leaf plum and still have it look good. It is not a desert species like mesquite or palo verde, but it can handle some lack of irrigation without dropping its leaves. Limb dieback of Chitalpa from 2013.             Unfortunately, all Chitalpa trees carry a vascular plugging disease unless propagated from seed. All the named varieties like ‘Pink Dawn’ were propagated from cuttings so they will be carrying this disease as well. You can’t see this disease outwardly but one of its symptoms can be leaf drop, starting particularly when temperatures get hotter.             Unfortunately, Chitalpa infected with this disease is not a good thing to have around grapes or oleander either. The disease can be carried to either of these plants where it can kill several types of grapes like Thompson Seedless or it can stay hidden and spread from a bacterial reservoir that can be housed in oleander.             The fact your tree has leaf drop in summer is suspicious. I would remove it. Replace it with a tree you like of a size in scale with your home. Single story home use a tree with mature height of around 20 ft. Two story home, look for a tree from 20 to 35 feet tall when mature. Smaller trees always use less water. Go to SNWA plant selector website to help you find one.

Q. My HOA wants a tree in my landscape and  so I planted a Mexican Bird of Paradise last April. The main trunk broke in a windstorm so now I have three trunks almost 5 feet tall and each a double thumb-width wide, starting 8-12” above the soil. How can I make it a tree? Red Bird of Paradise has beautiful red flowers and grows just about anywhere its warm enough.  A. I think everything hangs on the HOA definition of a “tree”. Most people consider Mexican bird of paradise a shrub, not a tree. A good argument could be made though, that many shrubs are transformed into trees through pruning . Many of our desert trees are “shrubby”. Sometimes popular landscape shrubs are pruned into small trees and called “patio trees”. Bird of paradise in tree form.             The second part this dilemma is whether the HOA considers a tree to have only a single trunk or multiple trunks. In the nursery trade there are “multi-trunked trees”like crape myrtle and strawberry tree. These multiple trunks usually vary from three to about five in number. So, get ready for a battle of definitions! Typically we think of Red Bird of Paradise as a shrub, not a tree. But if the plant is pruned and maintained as a tree, why not? I would probably chose to prune it as a multi trunk tree if possible.             In this case, I would prune it into a single trunk, so it does not look like a shrub. Also, when multiple “suckers” arise from a single trunk, as they did in yours, they frequently have narrow crotch angles that are weak and become problems as they get older. I haven’t seen your plant but removing all but one of these suckers gets rid of this potential problem.             Pick one sucker that is the strongest and remove the others as close to the trunk as possible. This sucker may or may not be flowering. Maybe it’s not the straightest of the suckers but it doesn’t matter. The growth of this pruned “shrub (now a tree) will straighten out in a year or two. In the meantime, other suckers may try to compete for dominance with the remaining sucker. Remove any competitors, when they reveal themselves, anytime of the year with a pruning shears or your fingers.             Remember to sharpen and sanitize any pruning equipment you use on these plants. You are at the mercy of your HOA so be kind to the Board Members.

            Lantanas are confusing but easy to grow just about anywhere, whether it’s in the tropics or the desert. They can add a variety of easy to grow colors that attract wildlife including butterflies to home landscapes. In cold climates where the ground freezes they won’t survive more than one growing season. They can be planted as annuals. Lantanas can handle most soils and rock without many problems.             In desert areas of the southwest they are cut back close to the ground any time after the first freeze and sucker from these small stems in the spring. A small amount of regular watering and fertilizer each year produces spectacular growth and flowers in just about any type of soil in full sun to partial shade. Lantana can be cut back really hard in after the tops have died for the winter.  As long as you leave one node or “joint” peeping from the rocks after pruning for the winter it will grow back.             The three lantanas popular in the nursery trades of the desert are hybrids of Lantana camara, Lantana depressa and the trailing type, Lantana montevidensis. Collectively we call them all Lantanas. But the nurseries might call them by more common names such as ‘Gold Mound’, Purple or Yellow Trailing lantana or the multicolored ones like ‘Confetti’ Lantana by Monrovia wholesale nursery. The color and growth options are wide ranging. Some lantana are considered “trailing” types and can grow quite large.             Lantana is in the Verbena family (this explains their flowering) and considered tropical  (this means they frequently freeze during the winter in Las Vegas). Their flowers are arranged in clusters called “umbels” (similar to carrot flowers) and vary in color from white to yellow to red to blue and all the colors that can be made when you mix these colors together. This means plant breeding results in a proliferation of colors and growth habits for consumers. Furthermore, these individual flowers (called florets) may change in color as they age adding another dimension in variety and sales. Some lantana flowers change color as the day goes longer.             Some of these plants are “bushy” and others grow much longer stems and considered “trailing”. Plant leaves are considered poisonous while their flowers and fruit are not and supplement the diets of many types of birds, butterflies, and lizards. Lantana is considered invasive in wet climates and hybridizes with native Lantana found in the east but should not be a problem in desert climates unless there is free-flowing water nearby like the Colorado River or desert springs. Lantana flowers are in umbels like carrot, onion, parsley or dill flowers.             Lantana propagation is extremely easy by cuttings or by seed in the late spring or early fall months.

Plants don’t care where their nutrients come from. But do you care about where the fertilizer you buy comes from?

Q.   I have an ash tree that is 18 years old. This year about 20 percent of the tree has dead branches while the rest looks good. We really do not want this shade tree to die. I have posted before on possible Ash Decline https://xtremehorticulture.blogspot.com/2018/01/dieback-of-mature-fan-tex-ash.html https://xtremehorticulture.blogspot.com/2017/10/limbs-dying-in-20-year-old-arizona-ash.html https://xtremehorticulture.blogspot.com/2015/06/ash-dieback-or-ash-decline-they-both.html A. That tree occupies a very important part of the landscape, I am sure. However, your ash tree may have an incurable disease called Ash Decline. In California they call it “Ash Dieback”. This disease, so far, is found only on ash trees, causes branches to slowly die in the canopy over several years. So lucky you! You can see this disease in many ash trees in the Las Vegas Valley.  But these dieback symptoms are similar to drought. Because this ash is growing in a lawn and probably getting enough water then this dieback is suspicious. This might be ash decline. Deep water it once a week for three or four weeks and find out. Deep Water and See if it Grows Better             Before giving up on it, try applying more water to the base of it in a larger area. Along with its normal water application, do this once a week with a hose and sprinkler and see if that helps reduce the problem. I use a mechanical water timer that costs about $12. I adjust the water delivery from the sprinkler to about the same size as the tree canopy and water for one hour. The water should wet the soil 18 – 24 inches deep when you water. Do this weekly for one to two months. If the tree starts growing more than you must apply more water to the tree.  Most ash trees are “mesic” and not “xeric” which means they should be given enough water when planted in a desert landscape. As any plant will, they will take water where they can get it. Are there enough drip emitters providing water to this tree? Even if you count the plants watered nearby? Maybe when its small but not when it gets bigger. If the tree does not respond with new growth, it probably has ash decline. Remove the tree. Applying a fertilizer once a year just before new growth is enough for trees. This would be February in the Mojave Desert. Note: I am no longer answering ash branch dieback questions here. I posted a page to it in my blog. I will respond to queries to me in an email but not post an answer.

Q. We would like to plant fruit trees but don’t have much gardening experience. Can we plant during the summer months? Are there types of fruit with a tougher skin so birds can’t get them? My wife loves avocados, so is that a possibility for someone without a green thumb here? Avocados come in all shapes and many different colors. These avocados were from Zimbabwe where it is warmer than Las Vegas. Las Vegas and the Mojave Desert is a bit cold for avocados so pick a variety that stays small and known for winter cold tolerance. A. I would not plant anything but palm trees, Bermudagrass, cacti and succulents from May through mid-September. Even good gardeners prefer not to plant during the hot summer months if they have a choice. Nurseries are pretty dead compared to spring. Good Gardeners Plant in Spring and Fall             Why? Anything you plant now is slow recovering from planting because of the late planting date, heat, and low humidity. If you see something you just can’t say “No” to, then buy it, put it in the shade and plant it as soon as possible. Plant in the morning when temperatures are cooler. After removing it from the container, transfer it to a wet, prepared planting hole as quickly as possible. Have a hose ready and plant everything wet, wet, wet. Plant in the spring and fall. fall months it is harder to find fruit trees you want but patience is good. Start Slow with Fruit Trees and Avoid Birds, Don’t Fight With Them             If you are new to gardening and fruit trees, start with a single fruit tree. Purchase a 5-gallon container tree or larger. Apricot is a good choice and harvest the fruit when they start turning a color and you see the first signs of a bird nibbles. This is a fresh bird peck in peach. Harvesting the fruit a bit earlier would forgo most bird damage when birds are not interested in your fruit yet.             You have 2 to 3 weeks to harvest everything from the tree so don’t take it all at once! Fruit will ripen first in the hottest part of the tree and work toward the coolest. So pick the fruit first that is farthest along. Picked fruit will ripen on your kitchen counter (or garage, or back patio and covered so the birds can’t get them) and still taste the same. The fruit doesn’t need light anymore to ripen and taste good. Apricots don’t have to be soft on the tree (which by the way is a little later than when birds first start pecking them) to be “tree ripened”. Avocado is ‘Advanced Gardening’ in the Desert             Don’t start with an avocado tree unless you are an experienced gardener. I am not going to get into the “why” here, but I will guarantee you failure if you don’t know what you’re doing. Search my blog for answers. Apricot or plum is much easier to grow here than avocado.

Q. I planted a rose bush facing south as a memorial for my Dad and I want to know how to help it along. It has holes in some of its leaves and a few yellow leaves. I saw one grub and I got some stuff to get rid of grubs.  A. Roses in a southern exposure have not had many problems provided they stay healthy.  Select a Good Variety First-Off Varieties of roses suited for desert environments handle hot locations well and may bloom throughout the entire winter if planted in the right microclimate. Like all roses, they don’t flower well during the heat which may start a month early (May) in southern exposure is like yours. List of desert roses. Aphids heavily feed on roses in the spring during cool weather before the flowers open. They start early and are aided in their transport from rose to rose by ants. Look at Your Rose Often             Look at the color of the leaves and the quality of its new growth to judge its general health. New growth should be vigorous and the leaves dark green. These are two signs the plant is healthy and growing. Hopefully, you amended the soil at planting, then use organic mulch on the surface of the soil surrounding them, fertilize them three times a year and water when they need it to keep them healthy. Even though leaf cutter bees damage rose leaves and petals, I like them. You can encourage leaf cutters with 1/4 to 3/8 inch holes drilled in 4×4’s. The females use the holes for laying eggs. They are solitary bees, not social bees like honeybees so they don’t need a hive. Disease and Insects             In dry environments like ours, roses have few disease problems and insect problems are rare, mostly occurring in the spring. We may see aphids and flower thrips in the spring and occasionally cane borer but it’s nothing to be alarmed about. You will handle these problems when you see them. Grubs feeding on the roots in the spring may occur and a systemic insecticide drench applied around the roots once a year will take care of them, and aphids, at the same time. This isnt rose but it doesn’t matter with leaf cutter damage. They always make the same size and shape holes in soft leaves and flower petals.             The size, shape, and position of holes in the leaves tell you a lot about which insect may be causing this. Most commonly it is leaf cutter bees. We may see the same damage on vegetables, basil, and other plants with soft, tender leaves. The strategy is the same. We leave these insects alone. They are good pollinators and so we choose to live with that kind of plant damage and understand its meaning. This isnt rose but iron chlorosis looks the same. Its always on the newest leaf growth and gets worse the newer the leaf. The available iron has been limited for awhile. In the spring, soil applications of iron work. In summer and fall you will have to spray iron on the leaves multiple times to get it to work. So get your precautionary iron soil application done early. Nutritional Problems             As far as yellow leaves go if they appear on older, bigger stems, ignore it. If these yellow leaves occur and new growth in full sunlight then we may need to look a little deeper on why.

Q. Now that it’s getting hot, my roses have stopped blooming. Should I keep feeding them or wait until the weather cools and they start blooming again? Can it hurt them when feeding in temps over 100? A. Roses are typically fertilized three times a year and avoiding months when it’s hot in Las Vegas, (June, July, and August). For convenience I suggest fertilizing on three holidays when cooler: Valentine’s Day, Memorial Day, and Labor Day. Rose fertilizers are typically high in phosphorus (middle number which in this case is 12). You can use any high phosphorus fertilizer as long as it has some nitrogen and potassium in it. Continued use of high phosphorus fertilizers are not the best idea, So substitute high nitrogen and high potassium fertilizers in the spring and fall months to push growth and keep it healthy.             On the Valentine’s Day soil application, include your favorite iron fertilizer as well. If you apply iron to the soil, only one application is needed. Generally, do not fertilize any plants during the hot months. If fertilizer must be applied during these months, apply it at half strength.

This is not a condemnation or anything bad about Indian products, just showing you that USDA is trying to protect the integrity of its organic branding. 90% of the time or better, the US organic label means the product was grown compatible with the USDA organic standards. Reminder to Certifiers and Importers: India Requires a Certificate of Inspection for Exports to the United States The National Organic Program (NOP) reminds certifiers and importers that India requires a Certificate of Inspection for the export of organic products to the United States. The Certificate is to be issued by a government-accredited certification agent via India’s TraceNet system. This final export transaction certificate is provided to the U.S. importer to validate the organic status and volume of the exported products. All certified operations receiving organic products exported from India are to obtain the Certificate of Inspection to verify organic status, in accordance with 7 CFR § 205.103, Recordkeeping for Certified Operations. U.S. organic regulations require certified operations to maintain records concerning the production, harvesting, and handling of organic agricultural products; and to make such records available to their certifying agent.  The NOP considers these Certificate of Inspection an essential record to demonstrate good control processes for businesses importing organic products from India. Additional information about this requirement is available on the NOP webpage for organic trade with India: www.ams.usda.gov/services/organic-certification/international-trade/India.