This podcast will teach you how to correctly select, plant and care for roses in our hot Mojave Desert climate.

Listen to this podcast so you know how to protect your tender plants from freezing temps.

October 29 There are some freezing temperatures projected by the National Weather Service for the Las Vegas Valley over the next few nights. Temperatures may drop as low as 28F in some lower parts of the valley. What makes this worse is that landscape plants are not prepared for freezing temps. They need time to prepare and progressively lower temps help them to do this. Sudden freezes are the worst and cause the most damage! Where are the Possible Problem Areas? Any lower parts of the valley where cold air has no where to drain or if it does drain, it drains slowly. Think of water. Cold air settles into low spots or pockets. But we really dont know how cold it will get. The NWS is telling you this so you have time to prepare and they usually are very cautious in their predictions. This bougainvillea froze back at the peak of its beauty Wind Makes it Worse If this cold air is combined with wind in your spot it will make it worse. Wind can channel between buildings and picks up speed in those spots. Wind removes any heat that might linger around and helps drop temperatures to freezing. Skies with good cloud cover and no wind usually don’t allow freezing temps if there is a threat. Look at the sky and cloud cover before you go to bed. Cloud filled skies mean warmer temps on the ground. Cloudless skies mean a greater chance of freezing. Plants and Plant Parts That Might Freeze Bougainvillea, a tropical plant that loves the heat of the desert, will freeze at 32F. It just does. Other tropical plants that freeze like this are tomatoes, peppers, eggplant and most of the hot weather vegetables. Plants that still have flower buds may lose them. Flower buds are very sensitive to freezing temps. They are more susceptible to freezing temps as they get closer to opening. If you have plants like Camelias that are loaded with flower buds, they may drop. Citrus too. Make a mental note which plants have flower buds. Flower bud drop due to a light freeze and damage to the edges of new leaves are signs of a light freeze. Summer Fertilizing and Freezes Never, never, never apply nitrogen fertilizers to plants that are tender after August 1. Nitrogen fertilizers push tender new growth that is more susceptible to freezes than phosphorus and potassium. This includes compost! No compost applied to freeze tender plants after July 1. The fertilizers contained in compost are slow release and last longer so stop applying them earlier in the year to tender plants. Fertilizers with anything in the first number, nitrogen, should not be applied after August 1 to winter tender perennial plants. Vegetables are fine because you will pull those to plant Fall vegetables. Protect Tender Plants Covering the plants with a freeze blanket or crop cover gives you about 5 degrees of protection. Thats all. Temperatures may get as low as 28F so freeze blankets or crop covers will work provided cold air does not get inside. So fasten them to the ground tightly to prevent wind and cold air from entering the inside. Apply them  to plants when the ground is still warm in late afternoon. Don’t wait until night because you are relying on heat from the ground to get captured under the frost blanket. Crop covers or frost blankets give you about five degrees of protection.

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.