February 2015 – Page 2 – Xtremehorticulture

Shoestring Acacia Height Can Be Lowered

Large shoestring Acacia. Some are more upright than others while others are more rounded. This is because of how they were propagated, grown and location. Q. I have a tall (40-50ft) shoestring Acacia tree that is too close to the house. The leaves accumulate on my flat roof and clog the scuppers. This has caused interior flooding on occasion as the water overwhelms the vents and skylights. My question is, can this tree be topped or does it need to be removed. A. Yes, you can reduce the height of this tree. There is a pruning technique to lower its height called “drop-crotching” which is very different from topping. Topping is extremely damaging to trees while “drop-crotching” lowers the height of a tree while maintaining the tree’s form as much as possible. This shoestring Acacia was topped. This is NOT how we want to lower the heights of trees. The method we are looking for is called drop crotching. Most likely the reason it had to be lowered is because the signage was blocked. This was the fault of the designer or landscape architect. Topping was the fault of the tree butchers. Very large trees cannot be reduced in size to very small trees. There is a limit how much a tree can be reduced in size by drop-crotching. When lowering the size of very large trees dramatically, reduce their size over a period of several years rather than doing it in one season. This is not the same tree but it was done by the same pruning crewon a tree close by.. These cuts were made in the wrong locations on the tree with absolutely horrendous care. When drop-crotching a tree you need to find very specific spots to cut where the form of the tree is not totally destroyed. You would first identify the vertical branches providing the most height. Trace these vertical branches to lower side branches. Remove the vertical branches just above the juncture with the side branches. You would repeat this at all of the locations that contribute to its unwanted height. By pruning in this fashion, you will retain as much of the trees natural form as possible. A guide to drop-crotching can be found http://pubs.ext.vt.edu/430/430-458/430-458.html If drop-crotching is not acceptable then removal is the only other option. Related post http://xtremehorticulture.blogspot.com/2013/05/can-i-prune-my-shoestring-acacia-now.html

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White Crust on Soil Surface Is Alkali or Salt

Q. I dug up some of our native soil and amended it with 50% planting mix. The next day after it dried, this white substance appeared on the surface. Is this salt or alkali? I know my soil will effervesce when you pour vinegar over it. Salt deposit left on soil surface of the readers soil. A. Salt and alkali are pretty much the same thing. Alkali should not be confused with alkaline. Alkaline refers to pH. Alkali refers to salts. Soils that create bubbles or effervesce when vinegar is applied to them have quite a bit of calcium carbonate, or lime, present. Salt deposit left on drip emitters The old-timers who grew things in desert soils would refer to “white alkali” and “black alkali”. I think the word “alkali” has remained in our vocabulary, but not the difference between white and black types, and it is just as confusing now as it was then. White alkali refers to the white salt accumulation on the top of soils. These white salts were usually sodium sulfate, sodium chloride, and magnesium sulfate. Black alkali on the other hand left blackish spots on the soil surface usually composed of sodium carbonate and organic matter. It was understood that black alkali was more damaging to plants in soils than white alkali. Salt deposit left on soil surface after an irrigation In fact, when ranking these salts and their injurious effects on crops, sodium carbonate was considered the worst while sodium chloride (table salt) was somewhere in the middle and sodium sulfate the least injurious. When you had black alkali salts, many farmers would just give up and walk away from those soils. The salts in your picture look like white alkali. I would have to guess it is a mixture of salts containing calcium, sodium and magnesium and carbonates, sulfates and chlorides. You wouldn’t know unless you submitted the soil for a soil test. When salts accumulate on the soil surface it is best to take a flat-nosed shovel and scrape off the top inch or so and dispose of it. Then begin activities that reduce the salt content. Salt deposits left on block wall after water evaporates. Most salts are removed with water and flushing. Level the soil surface as much as possible. Sprinkle the soil with water to push the remaining salts deeper into the soil. The idea is to push the salts deeper than the roots of your crops. If the soil does not drain easily, there may be a high sodium problem. If this is the case, apply gypsum to the top of the soil and rake or rototill it in as deep as you can. Then begin your irrigations. Gypsum is used to remove sodium from the soil and replace it with calcium. Sodium is a bad player in soils and prevents drainage. Substituting calcium for sodium improves drainage. Also, mixing compost in the soil will help in the removal of salts and make them less injurious to plants. Learn more about salts, soil, water and irrigation of the desert http://xtremehorticulture.blogspot.com/2012/09/there-is-lots-of-salt-in-las-vegas.html http://xtremehorticulture.blogspot.com/2012/01/removing-white-salt-deposits-on-walls.html http://xtremehorticulture.blogspot.com/2012/01/lining-raised-bed-garden-to-prevent.html http://xtremehorticulture.blogspot.com/2014/11/how-to-clean-drip-emitters-that-are.html

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Mulch Recommendations for Fruit Trees

1 Comment / What kind of mulch should I use around fruit trees, why mulch fruit trees / xtremehorticulture

Q. Please provide me with recommendations for types of mulch for fruit trees. A. By definition, mulches lay on top of the soil surface and are not mixed with the soil. There are organic mulches such as wood chips and there are inorganic mulches such as rock and plastic. Most mulches shade the soil surface, help to conserve water and reduce weed problems. Results in one year of fruit trees planted with and without surface wood mulch. Mulches made from wood decompose over time as long as moisture is present. Decomposing wood mulch enriches the soil. Rock, plastic and bark mulches do not. Their purpose is primarily to add beauty and reduce weed problems.In the case of plastic inches that are exposed to sunlight, they are intended to warm the soil early in the spring for faster route and plant development. Even if you have rock mulch, pull the rock mulch away from fruit trees and apply 3 to 4 inches of wood mulch in the an area as large as possible underneath the tree. Any wood mulch, not bark mulch, works well around fruit trees. The best kind is a mixture of different types of wood and decomposes in 2 to 3 years. You don’t want to use only bark mulch if your purpose is soil improvement. Decaying wood does take nitrogen from the soil but this is not a problem as long as trees and shrubs are fertilized annually. Wood and rock mulches help keep the soil cool, conserve water and reduce the work required for weeding. Only wood mulch enriches the soil. Rock mulch contributes to mineralization of the soil which means it contributes to the depletion of organic matter, it doesn’t add to it. Some of the best mulches for fruit trees are woodchips from a variety of trees but excluding trees with long thorns such as many of the mesquite trees, athel and salt cedar and palms. Palm trimmings decompose very slowly. Woodchips from trees with long thorns end up puncturing the bottom of a sneaker or vehicle tires. Just about any wood source will pose no problems including eucalyptus, cedar, and even oleander. An excellent mulch is also the residue left behind from stump grinders. Plastic mulches are used primarily for vegetable production and should not be applied underneath rock or wood mulch for weed control. Never. Learn more about mulches http://xtremehorticulture.blogspot.com/2014/05/can-i-use-chipped-pine-for-mulch-around.html http://xtremehorticulture.blogspot.com/2014/06/wood-mulches-for-desert-soils-are.html http://xtremehorticulture.blogspot.com/2013/07/come-and-get-your-mulch-at-unce-orchard.html http://xtremehorticulture.blogspot.com/2011/07/apple-tree-planted-in-rock-mulch-q.html

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Pruning Globe Mallow and Bird of Paradise

Leave a Comment / desert bird of paradise, How to prune globe mallow, how to prune Mexican bird of Paradise / xtremehorticulture

Q. We have a very old globe mallow shrub that looks bad after a frost. When and how should it be pruned to bring it back to its former glory? Do Mexican Red Bird of Paradise need regular pruning? How can one tell what and where to cut? Globe Mallow growing in extremely poor soils in Las Vegas. A. Globe Mallow can be a spring flowering perennial which means it can live for over two years provided it does not get damaged. Growing in the desert without irrigation it can be rather scrubby. But with a small amount of water and fertilizer it can be a beautiful woody shrub that can grow 2 to 3 feet tall and 3 feet wide. Close close-up of the flower of globe mallow growing under stressed conditions. If the globe mallow is looking kind of old and ratty you can cut it down to an inch of the soil and totally renew it or you can selectively cut down some of the older stems and renew it slowly. If you want to keep it bushy from head to toe then take about one third of the oldest wood out now, next year take another third and the following year take another third. This will renew it over a three-year cycle and help keep the foliage and flowers from top to bottom. You would do this pruning immediately after it finishes flowering. Flower of the desert bird of Paradise Mexican red bird of paradise usually gets a pruning to the ground every few years because of hard freezes. You have a couple of choices, much like your globe mallow. You can cut it to the ground or selectively remove one third of the oldest wood to the ground and in a three-year cycle. You would do this pruning during the winter months or before new growth starts in the spring or after flowering is finished.

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Forcing Tulips to Bloom Again

Leave a Comment / forcing tulips to Bloom, how to plant tulips, tulips and the refrigerator, Will tulips grow in the desert / xtremehorticulture

Q. I recently purchased tulips already in a container and they bloomed for almost 10 days. The roots were sitting in water, and I had to add a little each time so their roots reached the water. How can I save the bulbs for later planting next year? Can I keep them cold all year until next year? A. This is the beginning of February and you are not too late to plant now if you are able. Could you plant them in some containers and enjoy them that way rather than planting them in the ground? When tulips bloom, they are exhausted. They consume a lot of energy stored in the bulb to push the leaves and flower out. They need many weeks or months after that to rebuild that corm to its original size or even larger. So after bloom the leaves must remain attached to the plant while they rebuild the corm. Once the corm has rebuilt its size, everything green could be cut back and slipped back into the refrigerator for six weeks. They can be then be repotted again and forced to bloom. You can repeat this cycle several times as long as they rebuild the corms each time and receive eight weeks of chilling in the refrigerator. You can do this to nearly any spring flowering bulb. It would be very difficult to keep them for a year in a refrigerator or even specialized containers for that length of time because of storage diseases primarily. It should not stop you from trying it though. They will bloom again as long as they have about six weeks of cold temperatures. Give it a try!

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Trumpet Vine Adds Color to Desert Landscapes

1 Comment / desert, Does trumpet vine grow in Las Vegas, Mojave Desert, why is my trumpet vine not growing. / xtremehorticulture

Trumpet vine is commonly used in much colder, arid climates. It is not a true desert plant but can tolerate arid environments and poor soils. It does really appreciate amended soils, wood mulch and regular irrigations. Fertilize once a year in February with a fertilizer that promotes flowering of woody plants. It is a climber and under the right conditions can be extremely aggressive. Restrain with pruning the longest and most aggressive. Usual complaints are that the vine grows slowly or poorly. Make sure it receives enough water and mulch the base with wood chips. It may not do well in extremely hot microclimates. Trumpet vine over a wall in Las Vegas

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Prune Mexican Petunia Similar to Lantana

Leave a Comment / How to prune Mexican Petunia / xtremehorticulture

Q. I have a Mexican petunia (Ruellia) that is about 4 years old. In 2013 the freeze caused all of the stems to die back. I cut all of them off at ground level and the plant grew back nicely and flowered beautifully. Apparently, this winter the plant has very little dieback. Should I cut all of the stems off at ground level or just the ones that have frost damage? Will it flower from the existing stems or does it only flower from “new wood”? A. Mexican Petunia is considered an herbaceous perennial which means it freezes to the ground if it gets too cold and grows back from the base. It is summer flowering so the flowers develop on new growth. Flowers will develop on new growth from older wood as well as from new growth at the bottom. You have two choices. You can prune it to the ground again just as if it froze back. It will grow from the base and flower just like it had in 2014. That’s the easy way. Your second option is to keep it at this height and remove anything dead or weak to the ground. Next, you would cut the remaining stems back to a height where you want it to branch. Cutting it back or shearing it will cause it to grow more densely above where it is sheared and flower. The second method will give you a taller plant if you want one. If you need to keep it small, then use the first method. Remember to fertilize it now with an all-purpose fertilizer for promoting flowers such as a rose fertilizer, fruit tree fertilizer, tomato fertilizer or something similar. How to prune Lantana

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Avocado May Shock When Moved Inside

Leave a Comment / Growing avocado indoors, growing from seed, how to grow avocado, what causes leaf Browning on avocado, what causes leaf scorch on avocado / xtremehorticulture

Q. Last year I grew an avocado outdoors from its pit. As the temperatures began to dip I transplanted it to a pot and brought it inside. The older leaves have begun to turn brown and dry up. I fertilized it once since bringing it indoors. I water it lightly every other day as the leaves begin to curl up due to lack of water. A. The main reason leaves drop from an avocado brought inside is the change in light intensity or duration. Moving it from a soil to a container can cause leaf drop as well. Leaf drop can be caused by a watering problem. A fourth possibility are pests like mites. Avocado. Picture from the California rare fruit growers. Plants grown outside develop a different type of leaf than plants grown inside. The change in light intensity causes leaves grown outside, called sun leaves, to drop. The plant begins to add new growth with a thinner, larger leaf called a shade leaf. Disruption of the root system can cause leaves to drop. We call this transplant shock. It is also possible that the change in watering could cause leaf drop. Avocados are prone to mite problems so if there are mites on your interior plants it’s very possible they were transferred to the avocado. What to do? Make sure the avocado gets as much sunlight as possible. A south facing window is probably best. You need to provide several hours of sunlight to keep it healthy and prevent it from becoming spindly. Spider mite damage on interior foliage plant Water the soil in the container until water comes out the bottom. Do not water again until you can feel a dramatic change in the weight of the container. Another method to judge the moisture in the soil is to use a pencil or soil moisture meter. Push a pencil in the soil and see how easily it pushes down. A pencil is more difficult to push in dry soil than wet soil. You will feel the end of the pencil after you remove it to see how moist it is. A third method is to use a soil moisture meter you can purchase at any nursery or garden center. Mites are common problem for avocado. There are two methods you can use to inspect the plant for mites. First, take a white piece of paper and slap a yellowing leaf against its surface. Pick up the piece of paper and look at it carefully under a bright light. If you have good eyes or a magnifying glass you’ll see very small mites the size of a pencil dot crawling along the surface. You can also drag your fingers lightly across the surface of the paper and the mites will leave a red smear. Use a horticultural oil and spray the plant from head to toe to suffocate mites. Oils work well against active mites as well as soap sprays.

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Snails, Disease and Shade Are Related

Leave a Comment / How to control snails, lawn thinning, powdery mildew of rose, shade from trees / xtremehorticulture

Q. I have been noticing tiny little snails climbing up my red brick planter during the fall. I have thousands of those shells all through my planters and yard. My roses have now developed powdery mildew disease which they never have in the past. My lawn is thinning I think because of the snails. I have shade in my yard because of some older mulberries. I sent you some pictures of my yard. Readers yard with shade A. After seeing the pictures and reading your description I think that the shade is contributing to a number of things going on. Increased shade causes plants and the soil to stay wet longer. Snail shells from another readers question Staying wet longer favors snails and slugs. Increased shade increases the probability of powdery mildew and other diseases. Increased shade causes lawns to thin and eventually fail as well. You will see an improvement in everything if you remove some lower limbs of the trees. Limb removal will allow more light on your property and improve the roses, reduce disease problems, thicken the lawn and reduce snail problems. Cool season lawn grasses like fescue and ryegrass needs direct sunlight at least five hours a day or filtered sunlight so that no more than 50% of the lawn is shaded. Shading lawns and flowering plants more than this is going to hurt them. Shady lawns are not vigorous enough to withstand any kind of traffic. The lawn will thin and bare soil will appear in the more shaded areas. Plants that flower, like roses, have fewer blooms and the blooms will be poor quality in the shade. Powdery mildew loves the shade. Powdery mildew also likes splashing water. If there is overhead irrigation that is splashing on the leaves of roses and they are shaded, it will spread powdery mildew from rose to rose. Snails are difficult to control. The usual control methods are trapping and baiting. Trap snails by placing wet newspapers or cardboard between the plants. When the sun comes up, snails and slugs like to have parties under wet paper or cardboard. Powdery mildew on rose Pick them off of the underside of the cardboard or from the ground and put them in a plastic bag for disposal. If you do this on a regular basis, say weekly, you will start to put a dent in their population. Snail and slug baits also works well on snails. These are typically spread around the plants periodically and according to the label. These can be purchased in most nurseries and garden centers or online.

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Persimmons Will Grow in the Mojave Desert

9 Comments / How to grow persimmons, which is the best persimmon to grow, Will persimmons grow in the desert / xtremehorticulture

Q. I recently received a large bag of home-grown Fuyu persimmons given to me, grown in California. Will the Fuyu Persimmon tree survive our Las Vegas climate? If the tree will grow here? A. Nearly all of the persimmons will grow in this climate. I wouldn’t recommend the variety called ‘Hachiya’ but Fuyu, giant Fuyu, Coffee Cake, and most of the others will grow here if they are planted correctly in amended soil and not part of a desert landscape surrounded by rock mulch. Immature Hachiya persimmon. Hachiya may not be the best type of persimmon to grow in the desert unless you are in a backyard situation, protected from the wind and plenty of moist air. The fruit is good quality but the fruit may sunburn because of our high light intensity. It is important to surface mulch them with wood mulch, fertilize them once a year, prune them in a very similar manner to most other fruit trees and irrigate them as you would any other landscape plant. Giant Fuyu which does well in the desert

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