Xtremehorticulture

Avoid Salt Mayhem By Using Good Irrigation Managers

Determining the best irrigation schedule for a mixture of landscape plants is difficult enough but when salinity is involved, either in the soil or in the irrigation water, it complicates matters. Let’s cover some irrigation do’s and don’ts and see how salinity might affect the way we irrigate. Avoid Daily Irrigations Except for shallow rooted plants like lawns, annual flowers and vegetables in raised beds, daily irrigations should be avoided any time of the year. Many turfgrasses and annuals have root systems that extend into the soil 12 inches or less. During the heat of the summer and under desert conditions some of these plants may require daily irrigations. The deeper you should water. Lawns, annual flowers and annual vegetables have the shallowest roots and need to be watered the most often. The concept of irrigating nondesert landscape plants is focused on wetting the root system to its entire depth, allowing the soil to drain and re-wetting the soil again when half of this water has been used by the plant or evaporated. The Amount of Water Applied Varies with the Size of the Plant So we can see that the volume of water applied in a single application is directly related to the depth of the root systems of plants. When designing a landscape irrigation system we try, to the best of our abilities, to put plants with similar rooting depths on the same valve or station. Create irrigation zones in your landscape that reflect the needs of the plants in it. This is because the only way to water less or more often is to turn the valve to that irrigation line on or off. This is done with the valves. So each valve should represent different irrigation depths in your landscape; trees and large shrubs, smaller and medium size shrubs and small plants. Other valves could include annual plants and lawn and desert adapted plants which don’t need to be watered as often. You could even create another zone just for cacti. (This diagram originally appeared in Sunset magazine many years ago demonstrating Hydra zoning or mini oasis landscaping) More often than not we are handed an irrigation system with a mixture of plants that have a variety of rooting depths. When deciding an irrigation schedule for a single valve or station we generally have two options; set the number of minutes based on the average rooting depth of all the plants or let the plants with deepest root systems dictate the number of minutes of station runtime. Do We Conserve Water or Minimize Plant Problems? This decision depends on whether to conserve water or minimize landscape problems. When we decide to under irrigate some plants so the majority receive the correct amount of water, we may see some plant damage. If the under irrigation is not severe, we may see the slowing of plant growth, a decline in density due to leaf drop, leaf tip or burning of leaf margins. When plants are severely under irrigated then we begin to see branch die back and in some cases death. This is a mixture of a mulberry tree with cactus growing underneath it. Water the mulberry tree and the cactus gets over irrigated. Water only for the cactus, as this was done, and the mulberry doesn’t get enough water. Under irrigating, or applying less water than dictated by a plants rooting depth, can also impact safety issues. What happens if we under-irrigate large trees such as pines which have shallow roots to take up water but require deeper roots to anchor it in the soil? Current irrigation technology is based upon time management and varying how water is applied to plants. This technology varies the amount of water applied to plants by changing the number of minutes valves are open, increasing or decreasing the points of water emission or changing the rate of water applied at the point of emission. This translates to increasing or decreasing the number of drip emitters, bubblers, nozzles or spray heads or substituting old points of emission for new ones that have different rates of application. This is a highly sophisticated Hunter ACC irrigation clock. These types of irrigation clocks are expensive but give you a tremendous amount of flexibility. They wouldn’t be good for small landscapes but an excellent choice for large landscapes that have a lot of irrigation variability. Making these changes to an irrigation system that was designed by a professional and focused on the uniform application of water, more than likely will make the system less uniform and less efficient. This will likely result in substantially higher water usage. These types of alterations to professionally designed systems must be done with care. These six station inexpensive irrigation controllers are fine for most small landscapes that don’t require a lot of flexibility. When to Make Changes in the Irrigation System? There are some obvious cases where changes must be made. For example, changes must be made when some plants are receiving excessive amounts of water or not enough water while others on the same valve appear to be watered adequately. As plants get bigger, they need more water. When plants get bigger, their tops get bigger as well as their root system. Increasing plant size requires the application of higher volumes of water. Increased plant size dictates that the area irrigated under the plant also needs to be increased. Logic tells us we need to increase the amount of water by applying it to a larger area. Just because a few plants on an irrigation valve have grown larger seldom requires increasing the number of minutes of runtime. Other plants on the same circuit that received adequate amounts of water would then be over-irrigated for the sake of a few. Is Increasing the Number of Minutes the Right Decision? Of course increasing the number of minutes is the easiest solution to the problem but is it the right one? The quick fix of bumping up the number of

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Is ‘Last Chance’ Peach Good for Desert Climates?

Q. Will the fruit from a ‘Last Chance’ peach tree be tasty in Zone 10 or should I pull it? ‘Sugar Lady’ peach, not late but a solid performer with high sugar content from Zaiger Genetics. A. Last Chance is called “Last chance” because it is a late peach variety. ripening in late September and October. That’s the time of year you want really thinking of peaches so much but your mind starts to wander over towards apples, pears, and pomegranates. That’s a long time to keep a fruit on the tree and protect it from bugs, disease and keep the tree well watered. Personally, I like the earlier peaches because I can get them off the tree earlier so I don’t have to worry about them. Another great performer that has been around for a long time is Early Elberta with that Elberta flavor everyone thinks about when they think about a peach. It is a chance Peachpit that sprouted from someone’s garden, not one that has gone under the scrutiny by professional breeders. At Zaiger Genetics for instance, the folks that developed most of the pluots and other specialty hybrids, it takes about 5000 crosses and five or six years for each tree to get one successful fruit tree on the market. That’s a lot of investment! One of my personal favorites, but not so much because it is a great tasting peach but what peach is better when you can eat it fresh off the tree in mid-May! OMG. Early peaches, whether they are grown locally or imported from a warmer climate, command a higher price because they are early. I think part of the reasoning about Last Chance peach was that it was late when there weren’t many peaches around. The same idea just backwards. I fell in love with this peach when I first saw and tasted it. Indian Blood peach. It’s and old variety. Apologies if anyone finds the name offensive but this peach…words cannot describe the flesh color when it is ripe, the floral aroma and mild flavor of this  subacid peach.  Can anyone spell S-O-R-B-E-T? The tree will grow fine and produce fruit in the desert. I’m sure of that. But I don’t know about the quality of the fruit. I understand that it flowers relatively early in the season, the first week of February, which may be a problem with freezing temperatures in February and early March. Some peaches can sail through this kind of weather and others can’t. We had 5 of these Stark’s Saturn donut peach trees in the University Orchard. It was there second year in the ground. It was July and hot. I saw three peaches on  this tree. Two had already been nailed by birds. But this day I reached down to pick it, tree ripened, fully, slight give to the skin when you lifted it off the tree. Some juice came out on my thunbnail. It was 110F. The juice dried in a few seconds….leaving behind sugar crystals!!!!! Need I say more? I have never grown Last Chance peach in the Mojave Desert but I understand it can have a slight puckery taste, astringent, when it is ripe. It was being marketed in the Antelope Valley near Lancaster California, in the Western Mojave Desert.              I would grow this peach tree just for the flowers! But the fruit is excellent as well. Red Baron. i put in 50 at Ahern Orchard in Las Vegas (Bonanza and MLK) for the floral show in the spring AND great fruit as well. If you like the fruit, keep it. You might get peaches the first or second year you put it in the ground depending on the variety. I consider ‘Last Chance’ peach more of a novelty fruit because it produces so late.              So, my favorites usually produce in late May through July. Two notable exceptions are the Indian Free and Indian Blood peaches that produce fruit with lots of unique appeal when fully ripened. Two very late peaches for the home gardener are Carnival and Fairtime. They are proven winners in production. I have never cared for the flavor of either one but they are late, Sept and October, but at least I know they can handle some late frosts.

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Woodchip Mulch with Strawberries Might Be a Good Combination in the Desert

Q.  You have converted me to the doctrine of using woodchip mulch. Is there any reason why I couldn’t use wood chips in my strawberry bed?  My wife used to put strawberries in pots and they never did well.  Strawberries grown in Las Vegas Nevada, in Fall 2006 A. You can use woodchip mulch between strawberries. Apply compost right over the top of woodchip mulch and water it in to the soil when fertilizing. You will have to remove woodchip mulch at the end of two or three years when you pull out the old mature plants and replant with new ones. Plant strawberries in fall, not spring             Plant in mid-August, not in the spring. This is a mistake many people make. You may have trouble finding plants this time of the year since most information is focused on spring planting. But strawberries will struggle when temperatures get hot after planting in the spring. Strawberry demonstration plots prepared with compost in 2006 at the University Orchard             Improve the soil 50-50 with compost mixed with the existing soil before planting. I would include a starter fertilizer such as 0 – 45 – 0 mixed with that soil mix. A good quality compost can act as a fertilizer so don’t be afraid to apply it every three to four months after planting. Plant strawberries 12 inches apart             Here’s where I differ from what you might read. Plant them about 12 inches apart in rows 12 inches apart and remove runners when you see them. Some people also recommend removing the flowers as well. Planting in rows helps you find the berries later when the plants are full. Planting depth in A.             Plants should not crowd each other. You should see a slight separation between them for good production. Sunlight should hit the plant on all sides. Everbearing strawberry might work better             Select an everbearing type of strawberry rather than a main crop type. Main crop types produces only at one time of the year. Older varieties of ever bearing types like Ft Laramie, Quinault and Ogallala perform fine here during cool weather.             Everbearing types “trickle” their production throughout the year. This “trickling” makes them more productive here when the weather is favorable. They will produce fresh berries for 2 to 3 years before the plants need to be replaced. Strawberries do not set above 85° F             Strawberries will not set fruit very well when the temperatures are above 85°F. This makes hot, summer fruit production difficult with June bearing types of strawberries.             Keep plants alive during summer months until the cooler fall months return. Put them under 30 to 40% shade cloth draped on three-foot tall hoops during the summer months. Lay a frost cover over the top when temperatures are expected to freeze.             Water strawberries with in-line drip tubing running the entire length of the raised beds and spaced to 12 inches apart. Hand watering with the hose is very difficult. Keep soil moist but not wet to prevent root disease problems.

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When to Cut Asparagus in Las Vegas, Nevada?

Q. When is the best time to stop cutting asparagus here in Las Vegas? I have a bumper crop this year. A. There are a couple of ways to determine when to stop cutting asparagus. First way is when the spears start to get thin. If you have thin spears, it is a sign the stored food in the roots is starting to get in short supply. Winter color of asparagus in the Las Vegas Valley with light freezing temperatures.in December.             Stop harvesting. Let the ferns, tops, grow until late December and then cut them to the ground, fertilize with compost to get ready for the next seasons production.             The second way is a calendar method. Cut for about two to three months in early spring, let the ferns grow and cut these ferns to the ground in late December. Fertilize with compost and start the cycle again. Asparagus knife manufactured in Kosovo from a sample I took to new asparagus growers there.             By the way, remove the spears from below ground with an asparagus knife, not by snapping off the spears. An asparagus knife is like the old fashioned, forked dandelion remover. In a pinch, I use a long knife and push it into the ground, cutting the spear. Snapping the spears leaves a “stubble” on the soil surface which interferes with next year’s harvest and management.             Wash the spears and recut the spears to the proper length for cooking. Use the bottom parts of the spears, peeled, for asparagus soup.

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How Many Gallons of Water in an Inch?

Q. You posted a graph on your blog of inches of water plants use each day during each month during the year. How many gallons is an inch of water? Potential evapotranspiration for the Las Vegas Valley over 12 months in average inches of water used per day. Numbers across the bottom stand for months; 1 = January, 12 = December. A. I bet you want to know in minutes! That’s one problem when talking about irrigation. Irrigation clocks measure the volume of water in minutes. We apply water as a depth or in gallons, not minutes.             An acre-foot of water is roughly 325,900 gallons. An acre inch is roughly 1/12 of that which is 27,158 gallons. One inch of water in a one cubic foot container is 7.48/12 = 0.62 gallons.  Taken from my manual, Basic Horticulture             One inch of water applied to pure sand penetrates to a depth of about 20 inches. Fine sand, 14 inches deep. Fine sandy loam, 10 inches. Silt loam, 7 inches and clay loam, 6 inches.             The amount of water to apply is determined by the depth of its roots. The shallowest rooted plants are lawns, annual flowers and annual vegetables. We assume the depth of their roots is less than a foot. The next deepest-rooted plants are 2 to 4 foot tall perennials with a rooting depth of 12 to 18 inches. And finally, trees and large shrubs are the deepest with an effective route depth of about 24 inches.              Larger plants are given more water but watered less often because their “gas tank” (water held in the soil available to the roots) is much bigger. Plants that are shallow rooted like lawns, annual flowers and vegetables are watered more often because their “gas tank” is much smaller.             It is very important to group these categories of plants (lawns/flowers/vegetables, medium sized plants, trees and large shrubs) on separate irrigation valves. In this way they can be watered separately and at different times. Fourth and fifth categories, desert plants and cacti, could also be argued.

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Grapevine Not Leaving out This Spring. Dead?

Q. I have four grapevine bushes. We had a freeze these past two years. Two of them are doing fine, however, two others have not produced new leaves since last year. Does that mean they are dead? How would I check if they are dead? This grape was from a previous reader in Canada but a dead grape vine is a dead grapevine, right? A. Some grapevines are more tender to winter freezing temperatures than others. Some of the European wine grapes, or those with wine grapes in their heritage, may possess less tolerance to freezing temperatures. We refer to these grapes as “vinifera” type grapes. Thompson Seedless, for instance, is in this category and many California table grapes.             Most of these grapes will not tolerate temperatures much below 20° F. Expect them to freeze to the ground while other, hardier grapes may sail through the winter unharmed.             If you don’t live in wine grape producing areas, I prefer to grow grapes on their own roots rather than grafted onto a rootstock. If they freeze to the ground many of them will regrow from basal suckers. If they are grafted on a rootstock, then you might as well throw it out.             Cut the top of your grape back, close to the ground. Let it sucker from the base. Select the strongest sucker and re-tie it to a grape stake with nursery tape. Remove the other suckers.             If you push its growth hard with water and nitrogen fertilizer, you can reestablish it back on the trellis in one growing season. With some grapes I have been able to regrow it on the trellis and have it set fruit during first year of establishment.

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Never too late To Prune Lantana

Q. I put off pruning my lantana. They bloomed until about a two weeks ago. Now, they are starting to cycle through the dying and rebuilding process. Can I prune them back now, the normal way, and still have good growth? A. So, I take it, you did not prune your lantana this winter because it did not freeze. Or you just forgot. Now you are wondering if it’s too late to prune. No, it’s not too late. Do it now even though it’s starting to grow again.             Lantana is what we call an herbaceous perennial in our climate. Winter temperatures are usually cold enough that the top freezes to the ground each winter. Spring pruning removes the top, close to the ground, and it regrows again from its base or crown. This winter it did not get cold enough.             You know it has the potential to grow from its base. Cut it back hard to within 1 inch of the soil surface and it will “sucker” below these cuts. Give it some fertilizer and water after you make the pruning cuts.

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Tangerine Leaves Curling

Q. Please help me to recover my tangerine tree leaves curling inwards. Most have very small black spots on them. l observed the leaves and don`t see any insects. l do deep hose watering during hot summer days. Picture of tangerine leaves curling and dropping A. There are lots of reasons for citrus leaves curling. This problem is near legendary for citrus leaves but the reason is usually environmental and not from insects or disease. I’m not saying it can’t happen but it’s less likely. Citrus troubleshooting guide Arizona Cold weather             Since this question was sent to me at the end of winter, cold weather comes to mind. Cold temperatures can cause leaves to roll. Some say cold weather can cause leaf spotting as well. If leaf rolling was during the summer, guess what? High temperatures can also cause citrus leaves to roll. Watering             Moisture stress can cause leaf roll and leaf drop. When timing irrigations, make sure the soil is no longer wet when the irrigation water is applied. In the same token, make sure the soil does not get too dry between irrigations. Dry and wet soils can cause leaf rolling.             What’s more important, in my opinion, is overall tree health. Plants in poor health are more susceptible to problems than those that are healthy. Soil problems             In the picture you sent, I noticed the condition of the soil surrounding these trees. The soil looked pretty bad, even by Las Vegas standards. Poor soil conditions leads to poor plant health in the future.             Good soil health begins at the time of planting. I realize your tree has already been planted but soil improvement surrounding the roots at the time of planting is a huge future investment in plant health for years to come. In the future, excavate the planting hole 3 to 4 feet in diameter and 18 inches deep at the center. Mix good compost with your excavated soil at a rate of about 1:1; for every shovelful of soil, mix one shovelful of compost. What to do?             What can you do now? Put a half bag of compost on the soil surrounding the tree. On top of this, put a 4 to 6 inch layer of woodchips and water it in. Woodchips, where irrigation water is present, improves the soil health where most of the feeder roots of your tree are living. Spreading good quality compost at the base of trees for its fertilizer content             Improving the soil improves water, fertilizer and nutrient uptake by these roots which in turn improves the overall health of the tree. Soil improvement using this method helps remove some irrigation problems that could be causing leaf rolling. Overall, this means fewer problems for your citrus in the future. Community mulch pile at the University Orchard North Las Vegas             Get these woodchips free by visiting Cooperative Extension locations south of the airport or in North Las Vegas at the University Orchard in the Aliante community. For more information about these free woodchips call the extension hotline at 702 – 257 – 5555.

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Compost’s Role in Landscapes

            Using composts as soil amendments in vegetable gardens has been a no-brainer in the past. We knew it contributed to soil organic matter content. Most vegetables benefited from high levels of soil organic matter so we had no problem adding it to vegetable beds. How much organic matter is enough?             We were taught in school that productive agricultural soils generally contain from 2 to 5% organic matter; some required more than others depending on what was grown. In soils with adequate amounts of organic matter, additions were not needed. But that concept of “one size fits all” when it comes to organic amendments is being challenged and the challengers are winning. We have been educated that the ideal soil has 5% organic matter in it. But is that really enough for all plants?              We were told by scientists that landscape plants would not benefit from the addition of organic matter and that amending the soil at the time of planting was not necessary. Those of us working in arid and desert soils of the West and Southwest quietly challenged that generality and continued to add organic matter like composts to our landscape soils. We could see the benefit. What is a “healthy soil”?             Research during the past 20 years has challenged some of our previous thinking.  In many of our soils, regular additions of organic matter and its decomposition to humus is a necessary step in maintaining a vibrant and “healthy” soil and productive plants. Terms like soil health, soil food webs and soil ecology have become mainstream now. We have always been told that a healthy and vibrant soil contains lots of worms. But does their presence really indicate that’s all that’s needed?             Composting is the process used to convert organic matter into humus and employs many of the same microorganisms that perform the same function in soil. The concepts are very similar. The major difference is that composting provides a greater degree of control over organic matter breakdown than if it were left to an unregulated soil environment.             Fungal and bacterial colonies, earthworms and soil inhabiting insects feed on organic matter. Microbial slimes and gums are produced when organic matter is converted to humus. These byproducts of composting and organic matter breakdown help cement soil particles together. Most mushrooms are “saprophytic” which means they “feed” off of dead things, not living things. The presence of mushrooms in a soil is one sign that something in the soil is decomposing or breaking down. This decomposition is important for recycling, building organic matter and renewing life in the soil.             This altered soil structure is filled with voids that permit the entry, percolation and exchange of water and gases. Improved soil structure or “tilth” is a major benefit from the breakdown of organic matter or the addition of compost.             Byproducts from the decomposition of organic matter and the feeding by soil organisms improve the soil further by altering the soil chemistry and providing organic compounds that stabilize nutrients and assist in chemical reactions necessary for plant survival. Some companies capitalize on the idea that compost adds “life” to soils like this ad campaign by Viragrow, Inc.             When organic matter declines, humus levels decline as well. “Soil health” declines and with it landscape plants suffer. The rate of decline depends on many things including the type of soil, climate, management, nature of the organic matter and other factors. Renewing soil organic matter with compost             If deteriorating soil health is not caught soon enough, large volumes of quality soil organic amendments, such as compost, are needed in a process called soil remediation to bring the soil “back from the dead”. Compost additions to soil improve it by adding aeration, improving water retention while also improving drainage at the same time, and rebuilding life in the soil.             With these additions we see the improvement in soil health reflected in our landscape plants; more vigorous and healthier growth, more tolerance to environmental extremes, small amounts of fertilizer achieve greater results, less water is needed and plants experience fewer pest problems. Managing soil health             As managers of plants we must also manage our soils. The percentage of organic matter in a soil, and thus its humus content, is terribly important. Most soil test results provide the soil organic matter content.             But, is knowing the organic content of our soils enough? To know how much and when to put it back, it is best to know how fast it disappears. Knowing the rate of organic matter decomposition is a powerful management and budgeting tool. With this type of knowledge we understand how often and how much compost to budget for to maintain soil and plant health.              Similar to the composting process, the most powerful external factors controlling the conversion of soil organic matter into humus and its eventual disappearance are moisture and temperature. If soils are kept moist, accumulated soil temperature is the driving force in the loss of soil organic matter. At higher temperatures, soils decompose organic matter faster than in cooler soils. Hot, moist soils need additions of organic matter more often than cool, moist soils. Compost used as a fertilizer             Organic matter releases the nutrients it contains for plant uptake only when it decomposes. By decomposing, plants benefit as well as the macro and microorganisms that live in the soil. Decomposing organic matter also helps support beneficial soil bacteria, fungi and earthworm populations. The decomposition process of organic matter contributes to the breakdown of soil minerals which in turn further release the native plant nutrients they contain. There are enough nutrients in compost that it can act like a fertilizer. Composts very in their nutrient content so it is difficult to claim them as a fertilizer. Some contain more nutrients than others. It depends on the components used in making the compost.             In ways not well understood yet by scientists, the addition

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Smelly Potting Soil in Oven Disputed

Q. Earlier in March you talked about fungus gnat problems in potting soils. You recommended baking the potting soil in the oven. But I’ve heard this stinks up the whole house! I might try it in a gas grill outside, but not inside. Potting soils are lightweight soil mixes that usually contain peat moss and perlite as part of the soil component to minimize weight and maximize porosity. A. I used to think the same thing about baking potting soil in the oven. The common response by gardeners is not to do it for that very reason; it stinks up everything! But we tested it recently and it worked just fine as long as the temperature of the oven was below 180F. I think the smell problem occurs when the temperature of the oven is set too high.             I prefer “solarizing” potting soil in sealed, clear plastic bags for a couple of days to kill fungus gnats. The temperature of the soil does not have to be as high as it does to kill everything in the soil, a.k.a soil sterilization. If the temperature of the potting soil reaches 140 – 150 F for 30 minutes, through and through, it’s enough to kill insects.             To sterilize potting soil, completely ridding it of all insects as well as harmful microorganisms, the temperature must reach 180° F for 30 minutes throughout the soil. Attaining this temperature by solarizing is doable if there is plenty of sunshine, the soil is moistened, placed in a clear plastic bag and left in the sun long enough.             To be on the safe side, I solarize the soil with one side facing the sun the first day. Then I turn the bag over and solarize the other side on the second day. I check the temperature with a temperature probe through the plastic bag to make sure the temperature was high enough.             I would not recommend putting potting soil in a gas grill and firing the temperature up high. Low temperatures in gas grills are harder to control. Excessively high temperatures will “burn up” the organics in the potting soil. That’s when it gets stinky.             This cool, overcast spring presented some real problems. Cool temperatures and overcast skies did not allow solarization to reach the temperatures needed inside the bag. I enlisted the aid of a brave volunteer with an oven that had accurate temperature controls. She placed a half bag of potting soil on cookie sheets and into a domestic oven.             The lowest thermostat setting for the oven was 160° F. The temperature inside the oven stayed around this temperature for 30 minutes and the soil allowed to cool inside of it. Voilà. No fungus gnats and no off smell.

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