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Saturday, November 15, 2014

Scorpions Entering Home Since September

Q. I thought I would send this to you about scorpions in our neighborhood.  I live in the Coventry homes area adjacent to Anthem Country Club.  In the past 17 nights armed with a UV light, screw drive and instant light propane torch I have killed 205 scorpions around our house. So far we have only had two in the house, lucky us.  Is there a better way to control the scorpions than getting out every night and hunting them down? 
Bark scorpion
A. They have been trying to get in to warm locations since it started getting cold. All of these critters are cold-blooded so they will tend to migrate into warm locations when temperatures cool in the fall.
Homeowners threatened by having scorpions in their home or landscape may not get much comfort from this comment but these guys do a lot in controlling insects. They are insect predators. The good thing is they go after bad guys. The bad thing is they also go after good guys. They don’t discriminate between good insects and bad insects (from a human perspective).
There are different approaches regarding the management of scorpions. One method is total extermination such as you are trying to do. It will seldom be totally effective but it will reduce their numbers considerably.
Another management method is to put barriers down that prevent entry into the home. These also will not be totally, 100% effective but they should greatly reduce the numbers that enter the home. I generally recommend applying a barrier spray to the outside of the home, similar to the type of spray used to keep out spiders and cockroaches.
Actually scorpions are quite easy to kill with insecticides. They are very susceptible to them and often times are killed when they eat other insects that have come in contact with many insecticides used for spider and roach control. Any barrier spray application to the foundation of the home will work. I wrote a piece on this for Viragrow. I will attach a link to that publication.

Rosemary likes infrequent Waterings Or There Will Be Problems

Q. My Rosemarys are dying.  I planted quite a few thinking that I won't have a problem with them.  I lost two already that were planted about five years ago.  I just planted six more this last spring. What is going on? They get enough water and fertilizer.  I am afraid that I'll lose them all. The Rosemarys that died were planted on the east side about two yards away from the house.  They got a hole about 1, 1/2 feet deep and wide with mixed soil. They get sun in the morning and afternoon sun from the west.  The sprinklers go on only four days a week for 10 minutes in the summer, but in the winter I set the clock to go on only twice a week. It could be that there is bad drainage so close to the house. What else should I plant?  I noticed one Rosemary in the front of the house which is the west side, getting dry shoots, which I cut off.

Healthy Rosemary on top picture. Rosemary with problems on the bottom two pictures. The middle picture is most likely a water or drainage problem or possibly salinity.

A. It is possible that it is due to poor drainage but I still think your watering too often in the summer. They should be able to last longer between irrigations.

Posthole digger
Usually the soil surrounding the foundation is compacted for the slab’s stability. You could take a posthole digger and go down two or more feet and backfill this hole with amended soil and replant again.

I would dig a hole 3 to 5 times the diameter of the container you are planting anything in our soil. Three times a week in midsummer might be too often for rosemary unless you have really good drainage. It is not a desert plant but it does not like wet soil.

The soil amendments I am suggesting is really good for any plant, including desert adapted plants so you should be doing this anyway. It is hard for me to recommend something without knowing your needs, the site better and what is available.

The most common reason for Rosemary to die is because the soil stays too wet. You definitely do not want to water this plant daily unless the soil it’s growing in drains water exceedingly well.

The principal reason for the soil staying too wet is a lack of drainage. Typically if soils growing Rosemary stay too wet the roots will develop a disease called root rot and they die and collapse.

Shortly after that you begin to see the top die. Often times you'll see one or two shoots dying and then typically in the heat of the summer the whole plant suddenly dies.

Once the soil gets contaminated with this disease organism other plants susceptible to that disease and placed in that soil might also become affected. Replanting Rosemary in the same soil where it died is not a good idea.

It will like a place in the yard in full sun and hot. It will not like shady areas very much.
The next time you plant Rosemary make sure the soil is thoroughly mixed with compost to a depth of at least 12 inches. Rosemary originates from Mediterranean climates.

Mediterranean climates are characterized by hot and dry summers and cool and wet winters. Rosemary does very well in the heat and can tolerate the cold.

Fig Tree in November with Yellow and Scorched Leaves

Q. Can you tell me what is causing the leaf scorching on my black mission fig tree?  Is this normal for the fall?  I haven’t seen any pests or other obviously signs of disease. As you can see, it is producing its third crop of figs so I think it is receiving sufficient water. The first two crops of figs were good and juicy.  It is currently receiving 8 gallons of water of each time it is watered; just watered once a week now (as of November 1st).  Previously, it was receiving 16 gallons of water per week (i.e., watered twice at 8 gallons each).   Two days after it was watered, I checked the soil at about a foot below the surface and the soil seemed moist (not soggy).

Readers fig tree, scorched leaves and fig crop
I read in your blog that fig trees rarely produce a third crop of figs in Las Vegas so should I remove all of the figs and allow the tree to store its energy until the spring?

A. The leaf scorching that you're seeing is soil related. This usually means either the plant is not getting enough water or there are salt problems. Because you are producing nice juicy figs I am guessing it's a salt problem. I would do two things to your fig tree.

First I would move the drip emitters further from the trunk, usually about 18 inches. As this tree gets larger it will need more emitters. This tree should have four emitters 18 inches from the trunk and spaced like a square with the trunk in the center of the square.

Secondly, I would cover the area under the tree with more wood mulch to a depth of about 4 inches and covering an area at least 6 feet in diameter with the trunk being at the center of that diameter or circle.

The fact that you are getting nice juicy figs tells me the plant is getting enough water. What I sense is that the roots are now growing beyond the planted area and are encountering salty soils.

I would take a hose and flood that area with water to begin to push the salts away from the roots. You don't want to push the salts back toward the tree but you want to push them away from the tree or you want to push them deeper into the soil below the roots. This requires water and enough water to wet the soil down to a depth of about 18 inches.

If you can temporarily construct a berm or donut around the tree about 6 feet in diameter that will hold water you can fill this donut two or three times with water from a hose and that will help to flush the salts away from the roots.

The other thing you can do is take one of those small stationary sprinklers that attach to a hose and turn up the water pressure so that it sprays water on top of the soil in an area about 6 feet in diameter and flood that soil to leach the salts.

This might require that you turn the sprinkler on for 10 or 15 minutes several times with about an hour between. Otherwise you might get flooding. Once the water begins to flood or puddle you won't get very good leaching.

You want and even application applied to the surface of the soil with little to no puddling, entering the soil and pushing the salts in the wave to a depth below the roots which is typically about 18 inches deep. Don't forget to fertilize your fig tree this next January.

Buying and Planting Italian Cypress

Q. Two of my Italian Cypress trees died so I am replacing them. What size do you suggest I buy and how to I prepare the area prior to planting and correct way to plant them?
Italian Cypress
A. Get the smallest plants you can find if that size is acceptable to you. I would start with five gallon plants if it were me. If I can find 1 gallon plants, I would plant them. If they are well cared-for they will catch up to five, 15 gallon plants and even larger in just a short time.
Amend the soil with about 50% compost and to a depth equal to the depth of the container. The soil should be modified a distance 3 to 5 times the diameter of the planting container.
It is more important to amend the soil on the perimeter of the container than the soil below the container. However, and this is a big however in our soils, if the soil is particularly hard to dig beneath the container then I would take a post hole digger and dig a chimney at the bottom of the container and fill that hole with amended soil to improve drainage.
Thoroughly wet the amended soil several times after you planted the trees. Five gallon plants should not need to be staked. With improved drainage they should be able to handle more frequent irrigations without problems.
If soils do not drain freely you will have problems with these trees in future years. Fertilize them once in January or February with an all-purpose tree and shrub fertilizer.
Put them on a valve with other trees and shrubs. They will do fine on the same valve with most of your landscape trees and large shrubs as well as fruit trees.

Arizona Rosewood Good Choice for Desert Landscapes

Gopher Plants Dying

Q. What do think the problem would be with my three gopher plants? They seem to be getting enough water.
Readers Gopher plant
A. I am going to send you to a page at the Arizona State University for some general information.
This plant is a Mediterranean plant which means it likes soils that drain easily, hot summers within infrequent irrigation and cool rainy winters. Whenever I see branch die back on plants like this it usually indicates there is too much water remaining in the soil between irrigations.That is followed closely with root death caused by one of several plant diseases.

This means it is either watered too often or the soil does not drain very well or both. If this is the case, you will not solve this problem by simply giving it less water. You either have to take up the plant, amend that soil and replant it or move it to a new location that has improved soils and can handle frequent waterings.

Keep in mind, if this plant has a root disease you will be replanting it with that disease. If the soil is amended with high quality compost the plant may have a fighting chance of surviving through that disease.

If you cannot change how often the water comes on, you will have to change how rapidly the soil can drain the water. You will not change the soil by adding sand. This will make it worse. You have to use amendments such as compost, perlite, etc.

Once you have solved this problem you could cut this plant back to three or 4 inches in height and have it regrow again. Dead portions of the plant you can remove completely. Fertilize lightly in the early spring.

Tuesday, November 11, 2014

Pick Concorde Grapes When Ripe

Q. We had a nice sized crop of Concord grapes this past summer. The grapes were still a bit small compared to what I’m used to. They are more sweet than tart but I’m not sure how much longer to leave them on the vine. Any thoughts?

A. Grapes no longer develop sugar once they are picked. Other examples of fruit that don't ripen after picking are cherries and figs. Leave them on the vine as long as you can.
This is what Concorde grape should look like
Some fruits like peaches and plums continue to develop sugars and become sweeter after they have been harvested. When you pick grapes, figs and cherries, what you pick is what you get.
Bunches of grapes as well as the berries themselves ripen at different times. Usually a good time to harvest is when there is a small percentage of the berries that are overripe and beginning to shrivel.
Concord grape grown in the desert doesn't seem to develop the same color or sweetness that it does in New England.
Don't harvest grapes all at once. Harvest bunches which are ripe and delay harvesting those that are not quite ready. You may harvest 2 to 3 times a week depending on how hot it is.
The hotter it is, the faster they ripen. As grapes ripen, sugar content increases about 1% every 2 to 3 days. The best indicator is to taste them. If they taste good, they are ready to harvest.
Next year, remove smaller bunches so that remaining bunches are spaced about every 10 to 12 inches apart. Cut about one third off of the bottom of the remaining bunches. Do this when the berries are about the size of a small pea.
As long as the vines are getting plenty of water during fruit development and their thinned, you will get larger berries and bunches.
Just a note. Concord grape is a New England grape and will not perform the same in the hot desert climates.

Keep Green Bush Daisy out of the Rocks

Q. I put a Green Bush Daisy in late this last spring.  I got lots of blooms at first but now no blooms and the plant is yellowing.  What’s wrong? 

A. The Green Bush Daisy or Euryops should bloom for you all through the summer and stay dark green if the soil has been amended at the time of planting with compost and you apply fertilizers regularly.
If you put this plant in a rock landscape with very little soil improvement or have it surrounded in rock mulch then yellowing is quite common. It will do much better with improved soils and an organic surface mulch such as wood mulch.
For it to continue to flower through the summer, the soil should remain moist and not dry out. They will not like rock mulch at all if this is what you have.
Try adding some iron and good quality fertilizer such as Miracle Gro or Peters applied to the soil and watered in about once a month.

African Sumacs Pretty but Messy

Q. I have two 20-year old African Sumacs in my back yard that drop nearly all their leaves every summer.  Every fall they always come back.  Is this normal?  Beautiful tress but make a real mess! 

A. African sumac is a messy tree. There is going to be a lot of leaf drop and the female trees will drop a lot of berries. The seeds in the berries germinate easily and you may see seedlings popping up all over the place.
African sumac in Bloom in February

Sparrows and mockingbirds love the fruit from the female tree and help to disperse new seedlings all over your neighbor’s landscapes. The male trees produce pollen that is pretty allergenic usually around February or March. These are drawbacks to African sumac.
African sumac in Bloom in February

Best Small Apricot Is Gold Kist

Q. I would like to plant an apricot tree with my existing pomegranate and orange.  I would like one with the larger fruit and keep the tree to approximately six feet tall with regular pruning. Do you have any suggesting as to variety and where I can purchase one?

A. I hesitate a little bit just because I don't know what you're going to find in apricots locally. Selection of apricots is quite limited here in Las Vegas. You might have to order online if they even have left. You might find some Fall leftovers in the nurseries.
Winter form of 15-year-old Gold Kist apricot
One of my favorite apricots that stays about 6 to 7 feet tall and requires little additional pruning when trained early in its development is Gold Kist apricot grafted on to Nemaguard rootstock. This is a normal sized apricot tree. The fruit is excellent.

African Sumac Needs More Water As It Gets Larger

Q. We planted an African Sumac tree three years ago that is showing a lot of new green leaves now. Could you please let me know how much water it needs? It was deep fertilized at the beginning of spring.

A. Are you sure you aren’t seeing flowers? These trees flower in late Fall and into the winter months in the Northern hemisphere.
African sumac flowers
You realize that trees require more water as they get older and larger. So at three years of age they require more water than when first planted. I would normally add another emitter at this age to give it the extra water it needs.
In another three or four years it will require again more water than it requires now as it gets even larger. You would add another emitter again at this time to deliver more water. You should avoid increasing the minutes to give it more water.
Two drip emitters will not be enough for a tree this size
With that in mind, I would estimate that after three years in the ground your tree should receive about 10 to 15 gallons each time you water if planted from a 15 gallon container. I can't give you that estimate in minutes because I don't know how much water the plant is getting in one of its minutes.
You should determine how much water is being delivered to the tree. I'm not sure if you're using drip or not but many emitters state the number of gallons per hour that it is delivering or they are color-coded.
Add all these gallons together and divide by the fraction of the hour you are watering; 15 minutes you would divide by 4, 30 minutes divide by two. Do not water landscape trees and shrubs daily. This time of year once a week should be adequate.
You can fertilize the tree yourself. Place some fertilizer underneath each emitter or use fertilizer stakes such as Jobes next to each emitter.
Jobes tree spikes

If you are watering in a basin around the tree, sprinkle fertilizer in the basin and water it in and save yourself some money. Don't put fertilize closer than a foot from the trunk.

Don't Give Up on Petunias Because They Don't Flower

Q. I had two planters of petunias that stopped blooming and the leaves had lots of little holes. You told me that Tobacco Budworm was at fault and suggested applying Dipel or Thuricide.  After several applications we had lots of blooms on the petunias.  At the end of this growing season should we replace all of the potting soil in the planters with new soil in the spring?  Many thanks!

A. This insect can survive here through the winter in the soil. If these are potted plants then you can replace the soil but cultivating the soil several days before planting will help to expose them to birds.
I would watch for this problem in the future. These insects have wings in their adult form so they will fly into your flower bed from the neighbors. The two things to look for are the holes in the leaves and those little black specks which is budworm poop.

Next year in May or June start looking for that on your petunias and other susceptible flowers. I would not give up on petunias and Nicotiana just because of budworm. Put down a couple of protective sprays of Bt, Spinosad or any synthetic pyrethrin spray in April and May.
The fact that you put down Bt (Dipel or Thuricide) and had a reduction in the past problem tells me that it is working for you. Next year switch to Spinosad. The year after that use a permethrin spray. The year after that switch back to Bt. Keep rotating your pesticides.

Desert Greenhouses Should Be Tall and Shaded

Q. We would like to grow vegetables year-round for ourselves and family unless it is too expensive. We have power (110) available and plan to do as much construction ourselves as possible. We were thinking of constructing the perimeter with a 3 foot high block wall and then enclosing the top with some type of metal hoop structure with a translucent skin. Inside the greenhouse, the floor plan would be 3' wide and 3' high raised planters around the perimeter, and a 3x3 down the middle. We are getting too old to be on our knees. We have water available on a timer. We aren't sure about the hoop structure or the HVAC. What do you think?

A. I am hoping you are already good vegetable gardeners. Jumping into greenhouse production without being a good gardener will result in failure. I would recommend that you don't even attempt it unless you have solid vegetable growing experience already.
Temperatures in small hobby greenhouses are very difficult to manage properly. Greenhouses in the hot desert should be as tall as possible to get the heat off of the crop.
If you are hoping to save money by constructing a greenhouse and growing your own vegetables, you won't. Those vegetables will be expensive.
On the other hand, they could be better quality vegetables if grown correctly. The reason I say could is because you can get some very good quality vegetables in many of the grocery markets at different times of the year.
I personally believe that you should try heated hoop houses first before you invest into a greenhouse. Inexpensive hoop houses will help you understand the management practices you will need to adopt to make growing vegetables under protected culture a reality in the desert.
Shade is important in the summertime in desert greenhouses.
Hoop houses allow you to start your growing season 6 to 8 weeks earlier in the spring and extend this season 6 to 8 weeks in the fall. Doing this allows you to grow vegetables all year long here.
In fact, you can grow vegetables all year round here without any hoop house. You will not be able to grow any vegetable you want at any time of the year but you can grow vegetables in their appropriate season.
There are a lot of things that are going through my mind that you could try if you want to build your own greenhouse. It is not going to be cheap. In the hot desert you want these houses to be as tall as possible to get the heat up and off of the crops instead of captured under the canopy or roof.
These houses have to have very good ventilation. They need to have at least one air exchange every minute so you need excellent ventilation. This is usually done with exhaust fans that are sized so that you get the correct air movement and ventilation in the greenhouse.
There are two exposures that I think will work for you depending on the type of greenhouse. The first is an east facing greenhouse that receives protection from late afternoon Sun in the summer months. The house is oriented North and South. This exposure would require a minimum of six hours of full sunlight during the summer months. In the winter months it is best to get as much sun as possible.
Hoop houses like this one covered in shade cloth can be a valuable ally for quality desert vegetable growing.
You could keep it cool enough in the summer months using a swamp cooler and a ventilation fan or fans pulling the cool air through the house.
An alternative for an east facing house is to construct the North end wall as a very large evaporative pad with ventilation fans in the South end wall. The west wall would be a solid, insulated wall.
The Chinese style greenhouse is a south facing greenhouse with the North wall a solid block wall that can capture heat during the winter months. Extending from the top of the North wall is a shade cloth of about 30 or 40% shade that shades the vegetables during the summer when the sun is directly overhead.
Plastic covered houses in Egypt.
In the winter months when the sun is at a lower angle the sun will shine directly on the vegetables. This greenhouse usually has a solid wall about 3 feet high along the east, south and west sides. Hoops or lumber is used to construct the supports for the greenhouse clear “skin” on top of this low wall. Ventilation is from the East to the West wall. The house is oriented east and west.how to make a greenhouse, 
I hope this helps you a little bit. Perhaps I should put together some classes but like I said, it will be expensive to build these. My recommendation is to start with the hoop houses.

Major Cause for Gardenia Death

Q. I have a gardenia that is approximately four years old. It has bloomed yearly and was doing great until all of a sudden, literally, about 75% of the leaves turned yellow and fell off. It is on the patio, outside, where his always been in the shade and I water daily.
Gardenia with leaves yellowing.
A. I think your gardenia has developed root rot. This is fairly common in guarding. The symptoms of root rot is yellowing leaves and leaf drop. Frequently the plant dies a relatively slow death unless it's in the heat, then it could be rapid.
You didn't come out and say it but it sounds like the plant is in a container. When we grow in containers, the soil organic matter part of it (this is the part that helps keeps the soil loose and gives good air exchange to the roots) begins disappearing at a steady rate. It will be in a critically short supply by the third year. As soil organic matter disappears over time, the open spaces that help with drainage and air exchange, diminishes.
Gardenia with dark green leaves, a sign of health.
At the very beginning, a container soil may contain as much as 50% of its volume in pore space. Over three years this pore space could drop to only 20 or 15%. Basically the soil collapses, losing its pore space.
Collapsing soil becomes more dense, water drains through it more slowly, the soil stays wet longer, salts may begin to accumulate and the roots begin to suffocate. Soil diseases attack the weakened roots, roots begin to die, leaves begin to yellow and drop from plant.
This is why soils in containers need to be renewed every two to three years depending on the type of plant. Since gardenia is very susceptible to rots and grows much better in aerated soils, I would not go longer than every other year.
If the Gardenia is not too far along in leaf yellowing and leaf drop, you might be able to save it. Go to your favorite nursery or garden center and purchase a good quality container soil, enough to refill the container.
When you are there, purchase a chemical fungicide containing Subdue. Subdue fungicide does a good job in controlling several of the root rot disease organisms.
Applying a fungicide alone will not solve the problem so you must repot the plant as well. The plant can be put back in the same container if it is sanitized on the inside or use a different clean container.
Remove the plant from the container during the cool temperatures of the morning and out of direct sunlight. Once the plant has been removed from the container, repot it quickly because the tiny feeder roots die quickly when exposed to the air. Place the plant on a clean surface and gently wash the soil away from the plant roots.
Thoroughly clean the container and sanitize the inside of it with a 200 ppm solution of bleach and water. This would be about on tablespoon of bleach in one gallon of water. Rinse the container and wipe out the excess with a clean rag or towel. Let it air dry in the sun for a few minutes to let the chlorine disappear. Or you can use a clean, fresh container.
Once you have carefully removed as much soil from the roots as possible, repot the plant and use tap water to resettle the soil around the roots and remove air pockets. You will apply the subdue fungicide according to the label and water it into the soil of the repotted plant as a soil drench. Follow label directions.

Fertilize the plant as you would normally and watch for new growth to come from leafless stems that are still alive. Once every two years remove about one third of the soil from the container and replenish the container soil.

Plunge Fresh Fruit into Icy Water after Harvest

Q. I did what you told me to do to ripen the plums and it worked but they were mostly still very tart. Why did you tell me to put them in cold water after I picked them?

A. When you harvest fruit in the heat of the summer, the fruit will have a lot of excessive warmth or heat. The heat is from the environment as well as the fruit's respiration. We call this heat, field heat.
This heat can be very destructive to fruit harvested in the field and cause poor keeping quality. For this reason we want to remove this heat from the fruit as quickly as possible very soon after harvesting.
            One way to do this is just plunge the fruit into icy water for a few minutes and get it closer to room temperature. After it cools to room temperature, you can let it continue to ripen at room temperature.

Olive, Vitex or Crape Myrtle. Which is best?

Q. You helped me out a couple of years ago when I had questions about growing tree roses.  Now I would like your opinion on some tree varieties. This fall I would like to replace a couple of sumacs in my back yard. I really like three trees: olive, chaste and crape myrtle but I can't find anything online that compares these three trees.  Do you have a favorite?  Can you give me some pro's and con's compared to each other?

A. These three trees are dramatically different from one another in many ways, are used for different purposes in the landscape and have different watering requirements. All three will work here, Crape Myrtle being more difficult to manage than Olive or Vitex.
Crape myrtle growing in desert soil
Comparing all three trees, crape Myrtle provides the most year around beauty in the landscape. All of them are relatively slow in getting some size so you might shop for some larger trees if you want some instant impact after their planting.
Olive is the only evergreen tree in the group. I would classify European olive as primarily a 25 to 35 ft. shade tree that can take tremendous abuse. This tree will rebound if pruned badly so it is a relatively safe tree to have if you contract blow and go landscapers to do your property.
The other two trees will not rebound like an olive if they are pruned badly. In my opinion, Crape Myrtle might be ruined.
If you need something that creates shade, screens, or privacy all year round and is easy on water use, then you might consider olive. As you know we can only plant so-called fruitless olive in Clark County, Nevada. So you will be restricted to either Swan Hill or Wilsonii. However, you can add Monrovia nursery’s Majestic Beauty (Monher variety) to the fruitless list as well.
I have had numerous complaints about fruitless varieties producing fruit as they get older. It is believed this happens because these are grafted varieties and the top is lost at the bud union. The rootstock continues growing which is a fruitful olive and the tree becomes an olive tree that produces fruit with a fruitless tag. Others believe tags are mixed up in the nursery.
Crape myrtle trunk, young tree
In any case, don't expect your fruitless olive to be totally fruitless. If you need this tree to be totally fruitless, pick something else. Olive is relatively pest free. It requires minimal maintenance.
Both olive and Crape Myrtle get to be similar in mature size, around 25 to 40 feet. It will do well in a lawn or a rock mulch desert landscape. You would use this tree if you want a rock solid landscape tree that can handle a lot of abuse.
Crape Myrtle can also be spelled Crêpe Myrtle. In other parts of the country they come in a wide range of mature sizes ranging from 3 feet tall to 25 feet tall. Their flower color ranges from white to pink's, to reds, two lavenders.
Selection in Las Vegas will be much more limited but shop around. I have been surprised seeing selections in Lowe's and Home Depot. It is flat-out gorgeous tree if cared for properly. That is the key.
European olive
It is what we call a specimen tree, a showstopper when in bloom and even in the winter when it is leafless. It is meant to be a focal point for landscape. A larger tree will provide shade as it gets older but it is really meant to stimulate conversations and to draw your eye because it says, “Look at me!” when it is blooming.
Olive flowers
Crape Myrtle is a beautiful tree when it is blooming but I would argue that the texture of its trunk and its silhouette in winter rivals its flowers. The exfoliating character of the trunk is gorgeous up close.
If pruned properly its winter silhouette without leaves can be beautiful as well. The combination of flowers and uniqueness of its trunk and winter silhouette provides year around beauty.
This tree needs to be pruned professionally by certified arborists or by a knowledgeable homeowner. You do not want blow and go landscapers to touch this tree!
It will require special fertilizer applications including iron. It will do best with wood surface mulches but it can grow in desert landscapes as well. In desert/rock landscapes crape Myrtle will require more care to keep it looking good over the years.
There are dwarf varieties 3 to 6 feet tall, semi-dwarf varieties 7 or 8 feet tall, all the way up to full size which is about 25 feet in height. Most sold here are full-sized but shop around and you may get lucky finding other types.
Locally I have had complaints that trees were mislabeled and customers received a different flower color from what they expected. The other complaint was how they were planted.
Be very careful of companies that advertise free planting. This tree needs to have plenty of soil amendment go into the planting hole at the time of planting. When planting is free, the holes are dug way too small, very little soil amendment is used and the type of soil amendment used his lousy.
If I were buying a boxed, specimen Crape Myrtle I would want to see that the flower color matched the nursery tag and I would have the hole dug to my specifications by an outside party and buy my soil amendment separately from the plant purchase.
I would be placing this near a patio, a sitting area outside the master bedroom, near a place for people congregate in the backyard, or where you want people to look in the front yard. It has few pest problems.
Vitex or Chaste tree is a smaller tree than the other two. None of the three trees are trees that originate from deserts. However, all three will perform in a desert landscape reasonably well.
Vitex in bloom
On the positive side of Vitex is its flowers. It is sometimes called the Lilac chaste tree because it's floral display does resemble lilac and it is a good alternative to lilac in hot deserts.
Vitex is considered to be either a large shrub or small flowering tree. It can be grown either way. When in bloom it does attract butterflies with flowers ranging in color from lavender to mauve to off white or light pink.
Vitex in winter form
However there are some newer varieties with the improved floral color and with very long flower spikes up to 12 inches in length. You will have to look around for these superior varieties. There are just too many to list but a partial list can be found at http://www.plantintroductions.com/vitexanewbeginning.html  
The leaves and seeds are aromatic. It must be pruned carefully when young to give it good form or its winter look may not be the best. It can look kind of ratty in the winter if not pruned well.
It is good in a dry landscape, a show stopper from May to about September. Use as summer focal point. Few pest problems but could be damaged by blow and go landscapers if allowed to prune it.