Q. I really didn’t understand the “soil” here, did not dig large enough holes and didn’t amend the dirt when I planted my oleanders. It’s been 5 years and I’ve tried to correct their scrawny growth by adding plenty of mulch and fertilizing regularly but the growth continues to be weak.  Any suggestions how to encourage stronger growth? Its like backpedaling when you try to amend the soil after planting. Do it at the beginning and save yourself some grief and hard work. A. As a friend of mine would say, “Pay me now or pay me later.” At some point you will pay the price for good plant growth and modify the soil at planting time or later when it is more difficult. Amend Soil at Planting Time             Whether it is raw desert soil or imported “soil” brought into the development by the developer, soils in developments are typically horrible in the Las Vegas valley. Constructing planting holes at the very beginning and using amendments are extremely important for good plant growth. Its cheap insurance. Look at the size hole this guy dug for a 5 gallon mesquite tree. The brownish soil tells me it probably has 2% organic matter already but this mesquite tree will LOVE it. Just remember to mix the amended soil with native soil at the perimeter so there is no “hard edge” for roots to grow through. Oleanders like Wet Winters and Hot Dry Summers             Oleanders are Mediterranean plants. They grow well in a Mediterranean climate and soils but need some help when grown in the desert. The help is in the form of constructing a decent planting hole, using soil amendments that encourage good growth when the plant is young, and adding supplemental water. They love the heat and low humidity of our desert environment. Oleander is tough. If given enough water they can survive just about anywhere.             Now you have the job of amending the soil after it has been planted. Hopefully, your oleanders were planted with at least six hours of full sun every day. If not, prune any interfering trees so that they receive enough sunlight. Fixing Trees After Planting             Auger holes 12 inches deep around these plants so the holes occupy about half of the surface area. Fill these holes with a rich compost or make a rich compost by mixing a granular fertilizer like 16-16-16 with standard compost at the rate of two Grande coffee cups full for each cubic foot of compost.             Construct a donut around the plant for containing the irrigation water and hand irrigate for about two weeks filling the donut each time. After that, let your irrigation system take over. Prune it after about three to four years of growth and fertilize lightly each spring.

Q. I have a Chitalpa tree that faces west with lots of direct sunlight. The tree bark has separated from the trunk leaving the inner portion of the tree exposed. There are very few leaves on the tree. Help! Not the treaders tree but if chitalpa like this is put in a part of the landscape without enough water applied over a wide enough area under the canopy then the tree can struggle. A. The tree trunk has sun damage. Probably because the tree’s lower limbs were removed too soon. This sun damage has caused the bark to be easily lifted from the damaged part of the trunk. Sunburn has cooked the living part of the tree that faces West while the side facing East may still be alive. This is sunburn on a locust tree. This side is facing the sun, probably the south or west side. The tree is surrounded by rock and t his can reflect alot of heat and light back at the trunk and cause greater damage. Paricularly if the tree was limbed too high at the start.             Sunburn of the trunk can leave it exposed to other problems like wood boring insects (borers) and diseases like sooty canker. Let’s hope it is just sunburn on the trunk causing the poor growth. Locust tree has sunburn on the upper surface of its limbs.             My concern is that the tree might be surrounded by rock. Reflected heat from the rock can damage the trunk if the tree was pruned so the lowest branches are removed. Not a good idea when the tree is young and the trunk susceptible to sun damage.             When trees are young, leave the lowest branches attached to the trunk to help shade it from sun damage, particularly from the West side. Remove lower branches when the trunk gets older and develops a thicker bark layer that insulate it from direct sunlight. Tree wounds like this large one can heal by the cambium layer “rolling over” the damaged area and eventually burying it.             If there are no insect and disease problems, the tree will heal itself by “rolling over” its new growth on top of the damaged area. The tree just needs adequate water and fertilizer to do this.             Apply water to a large area under the canopy. This area should be at least half the area under the canopy. Apply enough gallonage so the applied water wets the soil to 18 inches deep. Although this tree can handle a rock landscape, water it as frequently as fruit trees and other non-desert landscape trees.

Q. I cut back my roses last mid-winter and they grew back just fine this summer. Later, all the leaves discolored, blotchy yellow. Any advice how to correct this and prevent it from happening next year? A. I would like to see some pictures showing me what you mean. But before I get into this, if you want roses in the desert I would go to the Rose Show on November 9. Rosarians are experts on growing roses in the desert. Some of them have 300 or 400 roses growing in their yards! They know roses. Come talk to them on November 9. When it’s hot, the roses use more water. When temperatures cool off, they need less water. If the soil stays soggy when temperatures begin cooling, the newest leaves begin to yellow. It’s an iron problem called chlorosis caused by suffocation of the roots.             I have seen this too many times! Rock placed on top of the soil contribute to a soil problem while woodchips won’t. Spraying the plants with iron fertilizer may be a temporary fix but not a long term one. Rocks covering the soil around roses eventually cause browning of leaves and dieback.             Roses like soils that allow water to drain from around the roots. To get this kind of soil there must be organics in the soil. Organics come from things that rot, not rock. Putting rock on top of the soil causes the soil to lose its organic content over time. But the slow digestion or rotting of organics like woodchips keeps the level of organics in the soil high over time. Expect your roses to look like this in a couple of years if you use rock.             The rotting of organics is caused by moist soil, plant nutrients in the soil like nitrogen, and warm soil temperatures. Rich compost has lots of plant nutrients like nitrogen and organics all bundled together. This bundle of organics and nutrients all rotting together helps keep a healthy balance of good chemistry that benefit the plant nutritionally and environmentally. Roses that grow this well will require compost and iron applications at a minimum.             To correct this yellowing problem requires some expense and work on your part. When temperatures start to cool off this fall, remove whatever is covering the surface of the soil. Mix iron chelate called EDDHA with some rich compost at a rate of about 2 ounces per cubic foot of compost. You can have roses in bare soil but amend this soil and improve it before planting. Notice the color. This color indicates it has at least 2% organics in it. Add EDDHA iron in January and a fertilizer.             Auger holes around the roses to about 12 inches deep and pour this compost and iron mix in the holes and irrigate the plants. Replace the surface cover with woodchips to a depth of 2 to 3 inches. Spray the leaves with a liquid iron fertilizer three times, three to four days apart.             In the early spring each year mix one ounce of EDDHA iron chelate in a bucket of water and pour it around your roses along with your favorite rose fertilizer. This should prevent leaf yellowing of roses in the future.

Q. I have vines producing melons during the summer. They wanted to split, and the taste was bland. But the same vine producing melons in the Fall were much sweeter! Can we conclude that when it is too hot sweetness suffers, and splitness reigns? Melons splitting due to irregular watering and lack of surface mulch. A. I wish it were that simple. It’s really a question of the type and variety of melon grown as well as time of year. Why Melons Split             During times of high water use some types of melons easily split. Splitting is usually an irrigation issue; soil gets dry followed by an irrigation. This happens frequently in the desert when growing in uncovered, bare soils. Water loss from the soil can be over 4/10 of an inch per day! This is about 50% higher than water lost from the same crops in melon growing regions. It helps if you make sure the soil is not dry when it enters the hottest time of the day.             Melon splitting is a variety issue complicated by weather and climate. If splitting is a problem with a variety, then select sequential planting times, or chose a different variety. It can make a difference. Write down your choices in a garden calendar and learn from these notes. Harvesting Melons             Never harvest melons that do not separate from the vines easily. Melons can be harvested early, and they will ripen, but they don’t get any sweeter than when they were separated from the vine. Not true of many tree fruits. You can have a fully mature melon that is not sweet if harvested too early. Melons Need Fertilizer             Melons are “hungry” crops and can deplete a soil of nutrients quickly. That’s why it will be necessary to add nutrients back to the soil at least yearly. Choose Varieties Carefully             Some varieties and types of melons just don’t perform ideally during our hot summer months. If you grow tomatoes, this might sound familiar. The heat is great for helping the plant make sugars but not in developing acidity. So, in the future keep good notes, pick varieties of melons that are consistent quality producers, plant them so fruits are harvested during cooler times of the year and wait to harvest until the melon slips easily from the vine.             Trials can be fun, but I would caution you about “putting all your eggs in one basket”. Rely on a proven variety that you like and combine it with something new.  And don’t rely on one season of growth. It can be a bad year. Three seasons are better and five are best.

Q. After reading about the many desirable qualities of screwbean mesquite trees, I am determined to plant two of them in my yard. However, today I searched the nurseries and discovered there was none to be found. One nursery offered to order them for me. I would rather see what I am buying. Do you know of any place that carries them?  Do I have to start my own from seed? Seed pod of screwbean mesquite A. Screwbean mesquite is a very nice small desert tree native to southern Nevada but not in high demand by the public. So, the local nurseries typically don’t carry them.  It’s a “chicken vs egg” problem in marketing and sales. Some nurseries will order them for you and that’s nice they offer that service. You may or may not be able to see the tree ahead of purchase going this route. Ask. Screwbean mesquite is an excellent small Nevada native tree that does not need much water to get to its mature size. This tree can be found at the Las Vegas Springs Preserve.             Locally, try the State Forest Nursery at Floyd Lamb State Park and check the availability there. (Update: they had them available). They have a website and post plant availability, but it doesn’t hurt to give them a call since not everything is posted. Contact the Nevada State Forest Nursery Screwbean mesquite trunk             On to propagation. The tree is easy to propagate from seed, cuttings or marcottage but for the inexperienced probably seed propagation is the easiest method. Just remember, all tree seeds in the Mesquite or Legume family will have a hard coating surrounding the seed that prevents accidental germination. You must damage this seed coat for good germination. The dried brown seedpods are where the seed can be found in midsummer             Pick seed from pods hanging from good looking trees in midsummer or when the pods are brown. Open the pods and pick ten of the largest seeds you can find. Damage the seed coat with sandpaper, small file or razor blade with as little damage to the seed as possible. Soak this seed in warm water for a few hours to get germination started.             While you’re waiting, fill a clean nursery container with potting soil to within one inch below its top lip. Plant the seed one-half inch deep and two to three inches apart. Keep seed moist but not wet. Don’t water too often!

Q. I have a Kumquat citrus in the ground for 8 years. During the last 2 years a lot of leaves fell off in the Fall leaving some branches leafless. Yet some branches stayed green with new shoots coming out. What might be the cause of the problem? A. Its very helpful when pictures are included with the comments. Sometimes pictures change everything! The tree, from the pictures you sent, looks dense and full, with a few “blind” shoots here and there. The tree might be too dense. Leaves need sunlight and produce a net energy for the tree to stay productive and healthy. Rather than leaves producing energy for the tree, leaves growing in total shade will be dropped from tree limbs because the tree must exp   end energy to keep them. Open the Canopy by Pruning             I would open the tree canopy to admit light to the inside. This will encourage fruit to develop throughout the canopy rather than just at its edges where there is light. Do this by total limb removal; “thinning” cuts. Prune so that limbs are four to six inches apart, not growing on top of each other. Look at the Ground             A trick to know if there is enough light penetrating the canopy is to look at the tree’s shadow on the ground at noon during midsummer. The shadow created by the canopy should have speckled light throughout it. If an area of the shadow is totally dark, then this is the area of the tree that needs to be pruned to admit more light. Admitting more light allows better fruit production throughout the tree canopy and removing a few limbs here and there during the summer does not hurt the tree. A dense shadow on the ground under the tree at noon during the summer indicates no light is entering the canopy to cause fruit buds to form. Time to do some light summer pruning!             Otherwise you might be giving the tree water and fertilizer, particularly nitrogen, too often.  Water when the soil moisture is starting to dry. On a soil moisture meter this would be an average of “5” on a ten-point scale at a depth of about 4 to 6 inches and measured in three different locations.   This moisture meter does not have its tip in the ground so it is reading the dry air at zero. Never water daily. Apply water to at least half the area under the tree canopy and apply enough water to get it 18 inches deep.

Q. The leaves on my 3-year-old almond tree, planted in a container, started to dry out quickly due to problem with drip system.  To compensate, I hand watered but apparently not enough.  Once system remedied very small new leaves starting to grow.  Will this tree survive the coming cooler weather?  I watered heavily and applied a tree and nut fertilizer. Almond trees flowering in the spring A.  I have seen this before on young almonds planted in the ground and it is usually, like you stated, an irrigation or drainage issue; the leaves dry up, turn brown and drop from the tree before winter. Once the leaves are without water for a day, the amount of hand watering you apply will not save any of the leaves. The leaves are goners. But the buds already formed for next spring will grow instead. Usually no flower buds, just leaf buds. That’s what happened to your tree. Almond regrowth in September after pruning a 12 year old tree 24 inches from the ground in August. It produced nuts the following year.             The tree will have no problems surviving the winter, with or without fertilizers, if the soil is moist and drains water. That’s not the issue. They used up buds saved for next spring. That’s the issue. Hopefully there is enough time remaining for the tree to grow new buds before it gets cold. If not, you might see a delay in leaf development and flowering next Spring. Almond nuts splitting and starting to dry before harvest.             Trees grown in containers are more finicky than those planted in the ground because the roots don’t have access to as much soil mass. The limited soil volume in containers makes watering and applying fertilizers more complicated; the tree runs out of both more quickly. Watering and fertilizer applications are in smaller amounts but applied more often to compensate for the small amount of soil. ‘ Almond Neplus Ultra in bloom in Las Vegas with size control             Almonds put on a beautiful floral display in the Spring. I can see why you wanted it in a container. Hopefully, you planted a dwarf almond like Garden Prince or All in One and used a large container. Remember it needs to be repotted every few years to keep it vigorous.

Q. Is it possible to mix Kentucky bluegrass, ryegrass and Bermuda for year-round greenery and thickness in a lawn? This is the textural difference between Kentucky bluegrass and an old fashioned tall fescue, probably Kentucky 31. A. The short answer is no. But if you are satisfied with a hodge-podge for a lawn that will slowly change over to Bermudagrass in full sun, or where irrigation is weak, then this combo is fine. It depends on the level of quality you are willing to accept in a lawn. Most people want a beautiful lawn and this approach will not produce a beautiful lawn. This is a winter picture of bermudagrass (brown) that has invaded tall fescue lawn area. The irrigated area is too narrow to support lawn grasses and the mowing height was probably short enough to encourage bermudagrass growth. Its the winter so bermudagrass is dormant.             I understand the temptation. Our valley and the Mojave Desert lie in what is called the transition zone for grasses used for lawns in the US. The transition zone in southern Nevada is not too cold for warm season grasses like Bermudagrass and not too hot for the heat tolerant Kentucky bluegrasses, perennial ryegrasses and tall fescue. The transition zone is a perfect place to grow all the grasses but grow them poorly. This is an old map from the Lawn Institute (no longer available online) showing the basic turfgrass growing regions. Green is best for growing cool season grasses like Kentucky bluegrass and ryegrass. The red zone is best for the warm season grasses like bermudagrass and centipedegrass. The yellow zone is ours…the transition zone where both types of grasses will grow.             These grasses are not managed the same either. Common bermudagrass can be mowed less than an inch, hybrid bermudagrass less than half an inch. But Kentucky bluegrass and tall fescue should be mowed at least 2 inches tall. Perennial ryegrass has the most versatile mowing height since it can be mown as low as hybrid Bermuda or as tall as bluegrass or fescue. Your selection of a mowing height will favor grasses that grow best at those heights. Turfgrasses for Urban Mojave Desert Landscapes             The winter months favor the cool season grasses like bluegrass, ryegrass and fescues. The summer months favor the warm season grasses like Bermuda. But bermudagrass is aggressive and will choke out other grasses unless you do something about it. This will require work and money on your part. Lawn Establishment in the Mojave Desert             Golf courses in Las Vegas were pioneers in using a mix of hybrid Bermuda and heat tolerant perennial ryegrass together during the 1990s. But this mixture was managed yearly. If it weren’t, the Bermudagrass would take over. The Bermudagrass was thinned out and heat tolerant perennial ryegrass, like Palmer and Prelude varieties, were sown back into it in the Fall. These management practices guaranteed a solid stand of Bermuda and rye during the summer months. Maintaining Tall Fescue in the Urban Mojave Desert Landscape Maintaining Bermudagrass Lawns in the Mojave Desert

Q. You mentioned on your blog that chelated iron won’t green up yellow leaves when it’s applied to the soil outside of the spring months. Why does this happen? We are a major tree company and see this sometimes. Also, how long should it take to see leaves become green again after we treat the tree with iron? A popular iron fertilizer that takes the shotgun approach is Kerex. It contains EDDHA chelate in small amounts along with iron oxides, iron sulfate, Milorganite and other ingredients that are a hodgepodge of fertilizers.  A. Two methods are used here to green up yellow leaves. It has a lot to do with the chemistry of the soil, more specifically how alkaline it is, whether it is an iron problem or not, and the type of chelate used in the iron fertilizer. It can get hard to predict if it will work or not. You will see later I will sometimes “shotgun” it if I am confident the yellowing is due to iron and the problem can be corrected. This, Sprint 138, manufactured by BASF, is an excellent EDDHA iron chelate and works great but it is expensive. One 5 lb bag is typically over $100. Less expensive EDDHA iron chelates are manufactured by China but I wonder sometimes about their quality. I have seen mixed results with off brands.             If I have the time, I will start with a spray bottle of iron fertilizer to see if an iron application will work or not. Spraying this liquid mixture on yellow leaves will tell me if the yellowing is due to iron or not. But it takes about 24 hours to find out. This is a 1 lb cannister of EDDHA iron chelate but manufactured by an unknown source and marketed by an American company. It costs considerably less than Sprint 138 and works sometimes, and sometimes not.             If the leaves change to a darker green in 24 hours, then an iron fertilizer application will work. Otherwise it’s a guessing game. For some people, 24 hours is too long to wait for an answer. This is another iron chelate labeled Sprint 330 and contains a different chelate called DTPA. It works IF the soil alkalinity is measured less than a pH of 7.6. Most desert soils are not that low in pH and so it does not work in many soils. It costs about half the amount as Sprint 138 so its tempting to buy.             Here’s where it can get tricky. If it is early enough in the year and the tree is still producing new leaves, I can apply an iron fertilizer to the soil, and it should work. If it is later in the growing season and the tree has, for the most part, stopped growing and preparing for next years growth, then the only thing that will work is spraying the leaves with a liquid iron fertilizer. This is another iron fertilizer made from acidified mine tailings that contain iron. If the pH of a soil is low enough then iron will be available to the plant.             If an iron fertilizer is applied to the soil, then the choice of iron fertilizer to use can become critical. If the soil is in rough shape and neglected, then use an iron fertilizer containing the chelate EDDHA. I would, in fact, use that iron chelate fertilizer whenever trees and shrubs are surrounded by rock. Because this can be a guessing game, I only recommend iron fertilizers that contain the EDDHA iron chelate. Its more expensive but I am more confident it will work under most circumstances. Another way of correcting yellowing due to unavailable iron…iron sulfate. It will work as a foliar spray if the iron spray solution has a pH of about 7 or a little above. Works great on lawns. But it will stain fruit, concrete walks and pools.             If the soil is in good condition, then usually any iron fertilizer containing an iron chelate should work. If you are price sensitive and always buy the least expensive product then, because of the soil chemistry, your selection may or may not work. I understand the reasoning, but it is a gamble. Sometimes you win, sometimes you lose. Iron sulfate staining grapes Iron sulfate staining concrete             If you see leaf yellowing about halfway through the year or later, then soil applications wont usually work. You must spray the leaves with a liquid iron fertilizer to cause the leaves to change from yellow to green. This can mean multiple applications of an iron spray. Please read my directions on how to make liquid iron applications to the leaves on my blog to improve your chances of success. Iron fertilizer containing HEDTA chelate plus 3% water soluble nitrogen and potassium for foliar spraying. If the yellowing isn’t due to iron, then the nitrogen will green it up.             What to do? I usually do both treatments, shotgun it, if there is a problem and I want the best chance of success. Two applications can be cheap insurance. If spraying works, it will cause the leaves to turn green overnight. Soil applications might take up to a week to see a change in leaf color and then it will be only in the new growth.             But applying the right iron fertilizer before the leaves come out in late winter or early spring can pay some dividends if you suspect leaf yellowing might occur.

Q. We have a palm tree that is getting taller and is now starting to lean. Should we be concerned about it falling over? A couple different tree trimmers have told me not to worry, but I’m not sure of their judgement. Leaning palm A. If the water is applied to the soil out a distance 5 to 6 ft from the trunk in all directions and two feet deep, I agree with your landscape professionals and not to worry about it. Roots grow where there is water. If water is only available to palm roots two feet from the trunk, then the tree will have a problem staying upright as it gets taller. Ever hear of hurricane palms? These are palm trees that were nearly blown over in typhoons or strong winds and continued to grow leaning. This is a coconut palm near our Family Farm, MoCa Family Farm, in Batangas, Philippines. It was nearly blown over in a typhoon but kept on growing…only at an angle.             One of the jobs of plant roots is to anchor the tree in the ground. Your job is to provide water far enough from the trunk so its roots can grow and anchor the plant. If roots can grow out deeply and several feet from the trunk, the roots will provide enough anchorage for the palm tree to stay upright.