Xtremehorticulture

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

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Leaves of Crepe Myrtle Yellowing

Q. The leaves of my crepe myrtle are turning yellow some show signs I think of a specific mold on underside of the leaves. Please advise in your usual expert advice. A. When yellowing occurs at the tips first it usually indicates a salt problem. This is possibly due to a lack of water or not enough water applied during an irrigation. It is also possible water is not delivered often enough so the soil becomes too dry between waterings. It is also possible it might be watering too often and not letting the soil dry between waterings. Crape Myrtle growing at the research center with wood mulch, annual applications of complete fertilizer, iron EDDHA and foliar application of Miracle Gro Look closely at your watering habits. If you are watering by drip make sure you put lots of gallons down every time you water. For trees this is gallons of water applied each time. The number of gallons depends on the size of the tree. As the tree gets bigger it needs more water applied at each irrigation. NOT watered more often. Make sure when you water that it is not daily or even every other day. This time of year every three days is adequate but put enough gallons down, not a small amount. Estimate how much water is delivered each time you water. You can use the chart below if you do not know the gph (gallons per hour) of your drip emitters. For instance if your drip emitter delivers 10 ml of water in 9 seconds then you have a 1 gph emitter. Increasing the total water applied will flush salts from the tree. Number of seconds to deliver gph (3600 seconds/hr) (3785ml/gal, approx. 4000) Gph     10ml     20 ml    30ml    40ml     50ml    60ml    70ml    80ml    90ml    100ml ¼           36 sec. 72           –           –            –           –           –           –          –            – ½           18       36        54         72 1            9         18        27         36           45       54         63         72 2            4.5       9         13.5      18           22.5 3            3          6           9         12           15 4            2.25     4.5        6.75     9            11 5             – 6             – 7             – 8             – 9 10           –            –            –           –           4.5      5.4         6.3       7.6        8.1       9.0 If you suspect you are watering too often then increase the number of emitters (this way you do not need to increase the minutes). Increasing the minutes means everything else will get more (or too much) water. If you suspect you are not giving enough water each time then flush the soil with water several times to remove excess salts and rewet the rootzone deeply. Put a hose at the base of the tree and let the hose run very slowly around the tree near the emitters for several hours. Or build a donut around the tree and fill it several times a few days apart. Or buy a small inexpensive sprinkler that goes on the end of the hose and let it run for 15 to 20 minutes. Repeat every other day three or four times to flush salts. This could also be from a lack of organic matter in the soil IF the tree is surrounded by rock mulch. Buy some decent compost and apply it to the rocks under the tree and water it in thoroughly. Do this two or three times this fall and repeat it in the spring.

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Reviving Crepe Myrtle After Neglect

Crepe myrtle with annual fertilizer applications Q. I inherited an established crepe or crape myrtle tree when we moved into a bank-owned vacant home two years ago.  The landscaping was pretty distressed.  I replaced the rock mulch with bark and the drip system seems to be working fine.  The tips of the leaves are dry and brittle and it blooms very little. A. You are probably going to have to give this crepe myrtle a jumpstart. It is good you put down a wood mulch with this type of tree. I hope this is wood and not bark mulch.             Since it is summer now you want it to push some new growth so you can see the tree’s strengths. Fertilizer is okay to apply now to trees and shrubs.             Use a normal tree and shrub fertilizer and apply it a foot or two away from the trunk and close to its source or sources of water. Water it in with a hose.             Construct a moat or a doughnut around the trunk of the tree at least 4 feet in diameter and 4 inches tall. This is nothing more than an irrigation basin to hold water. Fill this basin with water from a hose once a week for the next four weeks. Let your irrigation system run normally during this time. Crepe myrtle trunk and bark             Let irrigations push the fertilizer into the root area of the soil over the next couple of weeks. At the same time, add an iron chelate along with the fertilizer. The best iron chelate is iron EDDHA. You can find it in most nurseries now.             When the weather cools off in the fall, around September, spray the foliage with Miracle Gro fertilizer used for the promotion of flowering. Try using a hose end fertilizer applicator so you can get it to spray that high.             If you can’t spray that high, apply it to the soil and water it in.             Next spring start pruning out the deadwood in the canopy. Don’t climb in the tree, but rather I would use a ladder. This is time-consuming because you will be cutting a lot of tiny branches along with some larger ones. Basically you are thinning out the canopy and getting rid of branches on top of each other or crossing each other.             I question if your tree is getting enough water. If it is a sizeable tree it will require 30 or more gallons during each watering. You will have to look at your irrigation emitters and the time on your irrigation valve to figure this out.

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Pruning Crepe Myrtle Correctly

Q. When is the right time of year to trim my crepe myrtle tree and what should be done? A. They usually do not require much pruning. I noticed from your picture that it is planted close to your house Your biggest problems would be branches growing toward the house and walking under branches that are too low.             Remove branches growing toward the house at a “crotch” (where two branches come together) and remove with a “thinning cut”. A thinning cut is the total removal of a entire branch, leaving no part of it coming from the tree.             Limbs that are too low should be removed if people need to pass under the tree. This should also be done with a thinning cut. Remove limbs high enough to allow traffic under the tree.             Aesthetically, trees look better if you restrict limb removal so the tree’s trunk is exposed for no more than one third of its height. A common problem in pruning large trees in this town is excessive limb removal. Once removed, large limbs and the aesthetics it brings, is lost forever.            Crepe myrtle tends to grow branches too close together and sometimes on top or crossing each other. Look for these common problems and remove one of the offending branches with a thinning cut, leaving no stub.             Lastly, remove any dead wood or weak growth. Using thinning cuts will help preserve this year’s flower production.

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Reshaping Crapemyrtle After Bad Pruning

Q. There are 3 crepe myrtle in the back yard. One is very nicely shaped the other two were beside a patio overhang and side limbs were apparently removed to the height of the patio cover.  So we have 2 very TALL 20 ft  skinny trees with some green leaves at the top. I would love to prune the trees so they would grow out as opposed to up, thereby creating an umbrella shape to provide shade. Can I bend over the top branches and wire them to a more curved shape?  A. That is very unfortunate that these trees were pruned in this way.  I can understand your disappointment. Once that these lower limbs were removed you are correct, the form was destroyed. I doubt very much that any new growth would occur in the lower canopy area from larger diameter limbs. So you are right, you would be able to pull some of these larger diameter limbs into position to form a more rounded canopy. Let’s talk a little bit about how to do this. What you will try to do is to train the trees rather than prune them. Training is a different concept from pruning.  Pruning is the physical removal of plant parts. What you want to accomplish here is encouraging the plant to grow into a different form by manipulation that does not involve pruning or removal of plant parts in the beginning. You will be bending the branches into a different position that is more eye-appealing. This involves pulling or pushing existing growth into areas where it does not want to grow. When you pull or push plant parts into different positions, this will cause the tree to respond to this change in its shape. After this response occurs over the next couple of years , you will then begin pruning to maintain and encourage this change in its form. Timing when you pull  these branches into place will be somewhat critical. You will pull them into place when they are supple and can bend easily without snapping the wood. You are lucky. Crape myrtle bends well. The wood is sometimes used for bow-making. Bending the branches is best when the sap is flowing in the spring. Your visual cue for this is when you begin to see new growth this spring beginning in February. Do not wait too long or you’ll miss this window. I would gauge this opportunity from early February to about mid-March. The easiest would be to use non-abrasive cord, such as cotton clothesline, loop it around the branch you want to pull into place, pull it to the position you want and stake it to the ground. This position can be at any angle you want and in any direction you would prefer. Leave it tied in place for one growing season. That is enough. Once the branches are pulled and tied in place you will see a change in how the plant grows. You will see more growth coming from the upper sides of the bent limbs. This is a response of growth to new sources of light. We call this type of growth phototropic. Roots grow away from light and called negatively phototropic. Less growth will occur from the bottom sides of the limbs because there is less light there than before. As this new growth occurs from the upper sides of bent limbs is when you can begin pruning the tree — if you want. The branches that grow will “fight it out” for light and grow accordingly. You can remove wood if it is objectionable to your sense of proportion and balance. In most cases your pruning cuts will be “thinning cuts” rather than “heading cuts”. Thinning cuts remove entire stems or branches back to a crotch and do not leave any stubs or partial stems or limbs. Leave the strongest and healthiest growth if it is in a place that you like.

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Prune Crapemyrtle in Winter or Early Spring

Q. When is it best to prune crapemyrtle?  I’ve heard before winter, and again just before spring.  The last two years I trimmed back the branches (it is only about 5’ tall, about 1/3 of the way in late February.  What is right?  We live in Aliante. Crepemyrtle being evaluated at UNLV Center for Horticulture and Water Conservation in North Las Vegas. It is fertilized with an all purpose soil applied fertilizer, foliar applied Miracle Gro and EDDHA iron chelate along with a wood surface mulch. A. General rule of thumb on all flowering trees and shrubs is that pruning which affects flowering is always best done just after bloom so that the plant will have a chance to set flower buds for next season. If the pruning does not affect flower production, then prune in the winter.             Large limb removal should be done during the winter on all trees. If you are shearing it or in some way removing a lot of the ends of young branches then wait and do it just after it has finished flowering.             Large, heavier flower clusters and out-of-control growth results when branches are cut back severely. Flowers that result from these types of cuts can be so heavy that they bend branches toward the ground.  For this reason, do not cut the branches back to stubs every year.             Crapemyrtle blooms on new growth like oleander and pomegranate so it can be pruned in the spring and it will still flower normally throughout the summer. Summer shearing will affect flowering.

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Fertilizer Formula for Keeping Crepe Myrtle Healthy in Desert Landscape

Q. We have a crape myrtle tree in our southwest back yard. It gets plenty of water and I fertilized it last month with some Miracle Grow flowering fertilizer. At the time there were some burned edges on some of the leaves and some yellowing. Now it is really burned on the edges of all of the leaves with yellowing. HELP! Crape myrtle growing at Center for Urban Horticulture for 20 Years on Formula Mentioned Here A. A couple of things on your crape myrtle. I have kept crape myrtle growing in raw desert soil in good shape for 20 years at the Center for Urban Horticulture and Water Conservation in North Las Vegas. I used a combination of a general purpose tree and shrub fertilizer (16-16-16) plus an iron application combined with foliar sprays of Miracle Gro.             I don’t really endorse products but Miracle Gro is the one I used and have found to work just fine. You could just as easily use a different good quality foliar fertilizer for flowering woody plants. I apply the granular 16-16-16 in late January or early February using about 2 lbs. of fertilizer applied to the surface of the soil and watered into the roots without it washing against the trunk.             You can make some shallow holes in multiple places under the canopy and water it in thoroughly. At the same time, I also apply an iron chelate, iron EDDHA at the rate of a tablespoon or two scattered in the same holes and watered in so that none of it remains on the soil surface. It is light sensitive.             After about one month of new growth I then foliar fertilize the tree with a Miracle Gro spray or comparable product. I do both of these annually. You can do the same thing (except for the iron) by using a fairly large quantity of good quality compost annually. My guess is you either are missing the iron application, watering too often or not watering deeply when you do water.

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