Use Orchid Tree in Mojave Desert Landscapes

Q. I bought an Anacacho Orchid Tree at the Springs Preserve plant sale. Everyone tells me it needs rapidly drained soil, so I will use cactus soil. Should I put a couple inches of compost on top to enrich it? 

A. Interesting plant you bought. Not used much in the Las Vegas area because it’s not available but more popular in Arizona and Texas. Native to the Chihuahuan Desert. It’s a good choice for a desert landscape here.I don't have a picture of one but you can look at it if you click on the post below.

Click here to see and read more about the Anacacho orchid tree

            It’s a small tree, roundish up to about 12 feet but can get 20 feet tall if well-managed and planted in rich, moist soils.

            Drainage is correct. The soil must have good drainage so with no drainage problems in your soils it should be fine. Avoid layering soil. This impedes drainage. A cactus soil is not necessary but amended soil throughout the planting hole will provide enough good drainage.

            Mix maybe 20% compost with the soil used for backfilling around the roots or use a ready-made soil mix. It is native to the Chihuahuan Desert which has more organics in the soil than soils in the Mojave Desert. Compost amendments improve drainage through the soil. Rich compost provides fertilizer. With a rich compost, no need to fertilize for about two years.

            Make sure the soil at the bottom of the planting hole drains water. That’s important. The hole should drain water overnight or sooner after filling it. If not, plant it on a mound.

            Avoid extremely hot locations in the landscape such as South facing exposures near hot, radiating walls. The southern exposure is okay but don’t put it close to a hot wall. This plant grows in desert canyons in the wild. What does that tell you? Deep watering, open spaces surrounded by desert soils and rock and possible protection from late afternoon sun.  

            Most cold winters it should be deciduous in Las Vegas unlike places with warmer winters. Not terribly pretty during the winter months but it should give you good floral displays if pruned during the winter and not during the months.

Lawn Grasses That Grow in the Las Vegas Valley

Q. Are there other lawn grasses besides tall fescue and Bermudagrass that will grow here?

I took this picture many years ago to show the difference in leaf texture between some of the old-fashioned tall fescue and Kentucky bluegrass. The newer tall fescue lawn grasses have a much finer texture than the older ones but they are still a little bit itchy compared to the soft touch of Kentucky bluegrass and perennial rye.

A. Many different lawn grasses will grow in Las Vegas, but the problems are availability and which cultivars or varieties to use. Most people want what’s available currently in the Las Vegas markets because they are in a hurry and that narrows your selection to mostly tall fescue, sometimes called “fescue” by some.

This is St. Augustine grass growing in the Las Vegas Valley. It was substituted for Bermuda grass when shade was a problem. Like Bermuda grass, it is a warm season grass which means it turns brown in the winter. The major reason most folks don't use warm season grasses in the Las Vegas Valley is because it turns brown in the winter. But they can use considerably less water than cool season lawn grasses.

            Las Vegas sits in, using landscape lingo, the “Transition” zone for growing lawn grasses. There are three identified zones in the United States for lawn grasses; cool season in the northern states and warm season in the southern states. Just like onions.

Click here for the lawn grass map

            We sit in a third zone between them both called, you guessed it, the “Transition zone”. We can grow both cool season and warm season grasses. It’s the same with onions. In our location we grow both northern and southern onions. The same is true of our lawn grass. That can be an advantage, it can also be a problem. Our climate is not clearly cool season and not clearly warm season and so we have problems with both.

For identification of cool season grasses I use a combination of things but one is the leaf veination as you see in this picture. Both tall fescue and annual ryegrass have identical veins that run the length of the leaf blade. Perennial ryegrass, in the center, has that strong midvein.

            The major limiting factor is winter low temperatures that can kill some lawn grasses.

            The warm season grasses include all the different varieties of Bermudagrass but also zoysia, St. Augustine, Buffalo, centipedegrass and others. The cool season grasses include tall fescues but also Kentucky bluegrasses and perennial ryegrass. All warm season and all cool season grasses grow here but heat tolerance is very important with bluegrass and ryegrass lawns because of our high summer temperatures.

            Cool season lawns can stay green 12 months of the year here. Warm season lawns turn brown during the late fall and winter months. Some can handle overseeding in the fall with ryegrass if  a green lawn is wanted through the winter, but some do not.

            The predominant lawns in Las Vegas during the 1980s and earlier were Kentucky bluegrass for high-end lawns and common Bermudagrass for low-end lawns. Heat tolerant perennial ryegrass started making appearances in the late 1980s. Annual ryegrass was used for overseeding common Bermuda during the winter while managed back to common Bermuda in mid spring.

            The variety of a plant chosen, whether it’s a lawn grass or a vegetable, can be just as important as the kind selected. This is an important concept to learn.

Too Many Flies

Q. I have houseflies all over my lantana and roses! I find little black dots, which I guess to be eggs, on the leaves of those plants. I have sprayed with neem oil and Ortho Home Defense to get rid of them, but they keep coming. I don’t see damage to the plants, but I don’t want to have a fly breeding grounds in my garden. 

Flies are there for a reason. What do they need? Food and a place to breed. Flies usually indicate a manure problem and/or accessible food. Clean them up and the flies are gone.

A. Sounds like these flies are using your lantana and roses as a bordello. I don’t think the black spots are eggs. I think it is insect poop. Their poop from the sound of it.

            We will have to follow the KISS principle on this one. This means they are probably attracted to something to eat nearby such as dog food, animal poop, garbage cans, etc. Find the source of their food, control it and the flies will move on. That’s the only way I know to achieve long lasting, sustainable control. If you relied on sprays or traps it would be a never-ending battle.

Italian Cypress Gets Droopy from Watering Too Often

Q. I read your article in the newspaper regarding the effects on limbs from overwatering of Italian Cypress. I have 15 mature Cypress along a back wall. They are about 18 years old and 30 feet in height with 7 to 9-inch diameter trunks. They are watered 3 to 4 days a week in the summer, three cycles per day and 5 to 8 minutes per cycle. They each have three drip emitters with 10 gallons per hour. I’m afraid to change the watering cycle for fear the trees are used to more frequent watering.  I just don’t know.

When Italian Cypress has a droopy branches like this one, it is usually an indicator that it's getting watered too often. These are Mediterranean plants. They respond to water by growing more, similar to desert plants. When they grow more, this growth is frequently weak and can't support itself so it becomes "floppy". Notice this Italian Cypress is close to a lawn that requires frequent irrigation.

 A. Don’t argue with success if there are no problems. If the trees are healthy and you are happy with their appearance I would not change anything. Tree roots adjust to the location and number of emitters that are used. Once you begin changing this it requires the tree to adapt to the change.

            You are right. If you do change the watering pattern, do it in increments and don’t do it all at once. Do it gradually.

Italian Cypress should grow upright without floppy branches. It helps if they are surrounded by dry soil. Dry soil "pulls" water from the wet areas and helps them to dry out faster.

            But you should be aware of several things about watering trees. First, it is best if trees are watered less often but with more water. I think a saving grace for you is that you give one day of “rest”, without water, between irrigations. This gives the soil a chance to drain and the roots a chance to “breathe”.

            If soils around the roots of Italian Cypress are kept constantly wet, the tree can grow very rapidly. This is good, and this is bad. If Italian Cypress grows very rapidly then the limbs can become very long and weak. Limbs may begin to droop and not give the tree its characteristic rocket like shape.

            Secondly, the roots will grow near the surface of the soil, shallow, because they can’t get a good mixture of air and water to grow deeper. The soil is too wet. This may not help the tree anchor itself in the soil during strong winds. It might blow over easier. Perhaps the saving grace in all this has been a lack of applied fertilizer. I’m not sure.

            Thirdly, as trees get larger they need water applied further and further from the trunk. These additional drip emitters give the roots a chance to grow further from the trunk and provide better anchorage in the soil.

            Perhaps there are other plants growing close enough, or even a lawn, where the Italian Cypress can take on water. But only three emitters per tree, watering trees of this size, does not spread the water out far enough to give them strong support to keep them upright in strong winds.

Rosemary Dies When the Soil Is Kept Wet

Q. Last January we had our yard professionally landscaped which included 4 rosemary bushes near a west facing block wall. The bushes were thriving, doubling in size until the middle of summer. Unfortunately, three have died and the fourth nearly gone. Can you offer some suggestion as to how I can stop this problem from spreading?

Rosemary is a tough plant. It can handle some very tough locations. But it cannot handle soil that is constantly wet. The roots of this plant suffocate easily in wet soils, particularly during the heat of the summer.

A. Rosemary is susceptible to root rot diseases if the soil is kept wet. This can happen if it is watered too often, planted in soil that does not drain water easily or covered in rock so it never dries out. Plant death from root rot is frequently seen during the heat of the summer. This is not a problem that should spread beyond the rosemary.

This picture of Rosemary was taken in the middle of winter. It's one of those plants that blooms a lot and attracts honeybees when there isn't much else around that's flowering. It's a good plant to have near fruit trees that are early bloomers in the spring. It will handle about the same frequency of irrigation as fruit trees.

            Landscapers set the irrigation clock to water frequently after planting. This can be important during the first two or three weeks while plants get established in their new location, but irrigations should be less often once the plants begin growing. They assume that someone will adjust the irrigations later and not let them run daily.

This is what Rosemary will start doing when it's getting watered too often. First you see a small stem start to die, and then the center starts to die and then the whole plant dies. You drowned it. It's dead.

            Some soils do not drain water easily. In these soils it is best to plant on raised mounds or mounded soil so plant roots can grow into the surrounding dry soil in these raised areas. Use a similar soil to the existing one, just amend it with planting mix or compost.

            It is common for landscape soils to be covered with 2 inches of rock. Because the surface is covered in rock they are called “desert landscapes” which is arguably not true. Keep rock or any kind of surface mulch at least 6 inches from the base of the plant when it's young. Surface mulch will keep the soil from drying out and may contribute to the loss of plants if they are watered frequently.

            What to do now? You will probably plant again. Don’t plant in the same holes because the soil in these holes have a buildup of disease organisms. Plant at least 12 inches from these locations and reroute the irrigation. Water them daily the first week to get them established and then begin watering less often. In this case too much applied water is not important as how often it is applied. Water less often but give  them a generous amount when you do.

Consider Miniature or Genetic Dwarf Fruit Trees for Small Size

Q. I am interested in planting a fruit tree in my yard. After reading your blog, I was thinking of a fig tree, however I have been told that they can get very large. I wanted to stay under 8 feet tall and not difficult to grow. When should I plant it and where?

Fig trees like this one can be cut very short when they are older and they will still sucker and sprout, regrowing again.

A. Fig trees will grow very large but they can be severely cut back near the ground, if needed, and they will grow again. But I don’t think you want that kind of work and maintenance. There are some smaller fig trees like Black Jack fig but generally figs are large trees.

            Fruit trees that fit your description are called miniatures or genetic dwarf fruit trees. They stay very small but produce a lot of fruit of normal size. In my opinion, fruit produced by miniature fruit trees do not taste not as good as some fruit from regular fruit trees but pretty good for the casual backyard producer.

Genetic dwarf fruit trees, sometimes called correctly miniatures, stay small without a great deal of pruning but there are not hundreds of varieties to pick from. This is Apple Babe, a miniature apple tree growing in the Las Vegas Valley.

            The problem is terminology; the terms used to describe these types of fruit trees. The terms thrown around in nurseries casually are “dwarf”, “semi dwarf”, “miniature” and “genetic dwarf”. I just looked online and these terms are confused in most, if not all the online fruit tree nurseries. I’m assuming they’re confused in local nurseries as well.

This is a genetic dwarf or miniature peach tree growing in the Las Vegas Valley. There aren't as many varieties to pick from but they offer a fruit tree that stays small but still requires pruning for good production.

            A dwarf or semi dwarf fruit tree can be created by grafting a dwarfing rootstock onto a normal fruit tree. This could be called a “dwarf” or “semi dwarf” fruit tree. They will not meet your eight-foot tall criterion in most cases. The possible exception could be apple trees.

This is Gold Kist apricot on a semi-dwarfing rootstock. Many apricots are not large trees anyway but when put on some rootstocks they stay relatively small. This apricot did not need pruning for four years and was still very productive. An excellent landscape tree.

            Miniatures are sometimes the same as semi dwarf. Miniatures are sometimes genetic dwarfs. It depends on the nursery and their definitions of these terms. Sometimes nurseries create these names for marketing purposes and, in my opinion, cause a great deal of confusion.

When considering fruit trees for containers you might want to look closely at genetic dwarf fruit trees as a possibility.

            In most cases you are looking for what is called a “genetic dwarf”. But like I said, sometimes these are called miniatures. The only real way to know is to find out their true mature size. Nurseries think that small size can be a big selling advantage.

            If the term “dwarf”, “semi dwarf”, “miniature” or “genetic dwarf” is used in its description, check its mature size. It may not be exactly what you think it is. If the mature size is not listed, don’t get sucked in by the marketing. Assume it is larger than you think.

            The very small sized fruit trees that I refer to as miniature or genetic dwarf can be found in almond, peach, nectarine, and apple and vary in height from 6 to 12 feet tall.