Xtremehorticulture

Xtremehorticulture of the Desert

‘Interlaken’ Grape is a Close Alternative to Thompson Seedless

Leave a Comment / blackberry, desert, grape, selection /

Q. Can ‘Interlaken’ grapes take eastern, southern or western exposure?  What about blackberries? ‘Thompson Seedless’ dessert grape. Sorry, no pictures of ‘Interlaken’ but similar. Blackberries popping up through the mulch, after removal, where ever there is irrigation. Could be ‘Womak’ or possibly ‘Rosborough’ two varieties I would recommend for our climate. A. Both grapes and blackberries should be grown in full sun, away from hot walls, along with soil improvement, irrigation, and mulch. Put them at least 10 feet from hot west and south-facing walls so the heat from the wall during the summer doesn’t hurt them. Blackberries are more of a colder climate type compared to most grapes. Neither grapes or blackberries will do well in hot locations without the air mixing so it’s not so hot. ‘Interlaken’ grape is a seedless desert grape, similar to ‘Thompson Seedless’. In fact, ‘Interlaken’ grape has ‘Thompson Seedless’ genetics in it! For that reason, it should do well in Las Vegas. All blackberries like the cooler climates of the Pacific Northwest and do quite well there ripening in about one week or less. Research done in Yuma, Arizona, by the University of Arizona points out that a few blackberries have grown well in hot desert climates.   Based on that research I grew several varieties of blackberries. Both blackberry varieties ‘Womack’ and ‘Rosborough’ did the best in our dry intense heat. ‘Brazos’ was also recommended for desert climates but it developed leaf scorch during our hot summers. But ‘Womack’ and ‘Rosborough’ varieties didn’t. All suitable blackberries for our desert climate ripened in one day in May.

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If You Want it Green, You Will Like ‘Australian Racer’

Leave a Comment / Australian Racer, Groundcover, Myoporum /

Q. A neighbor suggested we look closely at Australian racer. It stays low and is green. Seeing it in place, we like it. What are your thoughts about it? Myoporum, or Australian Racer as it is known by local nurseries, was a ground cover substitute. As it got larger it would frequently die in the center after a few years. Its major problems are spider mites and root rot from watering it too often. A. “Australian racer” (Myoporum parvifolium) works as a sprawling groundcover as long as you don’t walk on it. It spreads in every direction about 6 feet or more (space plants at least 6 feet apart) but not considered a “desert plant” (mesic, not xeric). It handles the high and low temperatures of Las Vegas and used to be quite popular. It uses less water than a lawn but should not be watered every day. Ever. Water it as frequently as a fruit tree or eucalyptus. https://www.public.asu.edu/~camartin/plants/Plant%20html%20files/myoporumparvifolium.html             It’s negatives? If it’s watered daily, it will definitely get root rot and die. Watch this plant for spider mites during the heat. It can also be short-lived (maybe 15 to 20 years). When it is about 5 to 7 years old, cut the long and thick stems back or it develops stems without leaves toward the center. Use three to four drip emitters and wet the roots to about 18 inches deep.

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Roots of Plants Growing in Desert Landscapes

Leave a Comment / Uncategorized /

           Roots of plants do not grow separately. They grow together, all mixed up. Roots search for open spaces that are wet. They use the water for irrigated neighboring plants. Before now, we used to assess all the different plants’ water use and then add them together. Collectively they made up water needed by a landscape. But now, because we can’t separate the roots, we estimate the water use of a total landscape, not each individual plant and add them up. I fruit tree growing in a lawn obviously has roots which are mixed with the lawn. What do we water? We water for the lawn, not the fruit tree. Consequently the fruit tree will grow roots in the same soil space lawn roots grow. Plant roots growing in the desert follow water. Not entirely true because they’re looking for air as well. Air and water. A mixture. Ask any person growing in hydroponics. But water is their principal need. With rainfall it’s a lot easier. With rainfall, spinning a circle with an established plant lying horizontally, roughly describes where you can find its roots. In the desert it’s not that easy. The first rule of plants growing in the desert is that roots will follow water! Where water is applied, you will find the roots of plants. The roots of plants are roughly proportional to the height and width of the top of the plant if they get plenty of rain and the soil drains.https://www.openculture.com/2022/01/1100-delicate-drawings-of-root-systems-reveals-the-hidden-world-of-plants.html Plant roots are lazy. They use first, water that’s the easiest to get. The easier the water is to get at, the better. This is why trees growing in lawns have a mass of shallow roots! It’s difficult to get roots to grow deeper than “lawn water” but necessary. Shallow watering, as in a lawn, produces trees and shrubs with shallow roots. Tree and shrub root can grow deeper but they don’t have to. Trees and shrubs with roots deeper than the lawn are necessary. Deeper roots tolerate summer heat better. Trees growing in lawns have a mixture in the soil of lawn grass roots and tree roots. It’s because we water for lawn, not the tree. How to get deeper roots in Las Vegas? First, remove the lawn during cooler weather, starting in early fall and later. Use the weather app on your phone. September is usually okay but don’t remove lawns during June, July and August which are typically our hottest months. Secondly, move the irrigation emitters that are near the trunk. Soils are different but drip emitters starting 12 to 18 inches from the trunk are close enough. Emitters spaced 18 inches or more under at least half of the canopy is usually enough. As these trees and shrubs get bigger, they will require extra emitters. Space extra emitters the same as the others. There is a river a couple hundred yards from this mesquite tree. Tree roots go after water only if the soil is wet nearby. Avoid watering daily. It’s not necessary and it works against you. Every landscape is different, but there are normally only three types of plants that require daily irrigation in the summer: lawns, vegetables and annual flowers. Give trees and shrubs at least one day of “rest” (without water) before watering again. Do you want your plants to have shallow roots or deep roots? 

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Native Desert Soil Is Productive for Vegetables

Leave a Comment / Desert soil, large vegetable area, native soil, no raised bed /

Q. My garden area is about 40 feet long x 40 feet wide. The soil is native. How much compost do I need? You will need at least a truckload, that’s 2 cubic yards. Continue to add compost as it needs it, probably every one to two years. A. If this is a light tan native soil, you will need between about 1 inch of compost, during its first year, laid on the top of this native soil and rototilled to a depth of 8 to 12 inches. You would need to order about 3 cubic yards of compost to accomplish this. If you are ordering by weight this amount of compost totals about 4500 pounds, but its weight depends on its degree of wetness. A standard pickup truck will carry about 2 cubic yards, dry, to give you an idea. In the following years one pickup load every one or two years will be plenty to boost production. Basil is growing with a rich compost and no extra fertilizer is needed. Straw is used as a mulch to conserve water and keep the soil cool. Native desert soil is used an enriched with compost. Depending on how “rich” the compost is, a small bag of starter fertilizer high in phosphorus (the middle number) may or may not be needed by rototilling, or soil mixing with a shovel, compost to that depth. These are very large plots growing eggplant in compost amended native desert soil with drip irrigation. These raised beds are without sidewalls, just the natural slope of the soil keeps it together. After the compost has been rototilled and water applied to this amended soil, the soil will become darker brown in color. Approximately one pickup load will need to be added to this area every year, or every other year, depending upon the garden soil texture and color. During the first season of growth, the amended native soil will be productive. It will take about three seasons of growth and watering before the soil is highly productive, each season getting better. Don’t walk on this soil except for planting and harvesting. Instead, created walkways between growing areas should be shoveled about 18 – 24 inches wide and the garden soil leveled. No sidewalls need to be constructed in this set up.

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Cutting the Roots of Asparagus for Planting Among Fruit Trees

Leave a Comment / asparagus, cutting the roots, intercropping with fruit trees /

Q. I see online some people cut the roots of asparagus before planting. I did this last year. Is it a good idea? I was thinking of planting asparagus at the base of fruit trees. It makes them easier to plant, but are there consequences? Asparagus can get 5 feet tall or taller after harvest. A. Your question is about cutting the roots of asparagus and what consequences might occur. I must guess since I don’t have much experience with that. They are both deep-rooted, so I don’t think there is a problem with irrigation and spear production provided the roots are covered with clean (no rocks) soil when replanted. It’s best to use clean soil directly above the roots. Rocky soil covering the roots may lead to the growth of “crooked spears”. The crown of asparagus will have to grow some new roots for storage. There is one major problem. It has to do with interference between the fruit tree and the asparagus. After the asparagus has been harvested, the shoots are allowed to “fern” up so they can gather energy for next year’s production and the roots can grow. These ferns can be 5 to 6 feet tall when they finish growing. I could see how these might grow up into the branches of the fruit trees. Ferns can be cut without any problems. Cutting the ferns will interfere slightly with the number spears you collect in the spring, but not much. Shade can be a problem when fruit trees are grown close together. This happens after about 4 to 6 years and it may be too dark for some plants. A minor problem (maybe??) is the amount of light available. As the fruit trees get larger, they will create more shade. The ferns will not collect as much sunlight in this location. Regarding the asparagus crowns competing with the fruit tree for “root space”, it’s true but not a huge problem if you don’t put too many crowns at the base of the tree and plant them where they will get light in the future. I think you are fine with 3 to 4 crowns planted there about 18 inches or so apart.

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‘Iceberg’ Roses are Older But Worth Planting in Las Vegas

Leave a Comment / iceberg, Las Vegas, rose /

Q. This may be a bit too amateurish for your column, but I need help with ‘Iceberg’ roses. I pulled the rock away and fertilized this past spring. I thought the roses I planted in pots would do better, but they don’t.  I ask the nurseries when I go but get conflicting information. Why are there holes in the flowers?  When I see dark leaves that look diseased, I pull them off.  When I deadhead and trim back (5 sets of leaves), I sanitize the shears to not spread any potential disease from bush to bush.  Is there anything else you see? Iceberg roses are an older rose but still valuable for planting in Las Vegas. A. Whenever I hear roses, my thoughts go to plant location relative to the house and soil enrichment. They are the most important. Make sure that any type of rose is a good 3 to 4 feet from any hot wall. Roses grow best in full sunlight with plenty of air movement or on East or North sides of homes in the hot Mojave Desert.             During the planting season (never summer), the soil should be amended with compost and covered with a 2 to 3-inch layer of wood chips. The best woodchips to use are those that are chipped from local trees rather than a “bark” mulch. The true iceberg rose is a floribunda type that is worthy of containers in Las Vegas. Here it’s planted in a container but the soil must be changed, or at least renewed, every three or four years.             The old-fashioned “Iceberg” rose is a bush rose (considered a Floribunda type), 3 to 4 foot tall and bearing medium-sized, white flowers in the spring and fall months here. Iceberg roses are pruned at the same time as other roses, usually in late January. The iceberg rose has been bred to be a climber (10 to 12 feet) in more recent years with the same color flowers and scent as the original 1958 rose.            I don’t see a problem with this Rose except a lack of fertilizer and water. Diseases and insects of roses in our Mojave desert climate include powdery mildew, iron deficiency, bacterial galls, spider mites, thrips, and cane borers. Try fertilizing 3 to 4 times each year during the cool months, in the first fertilizer application (spring) include an iron fertilizer, and water the plant twice a day during the heat of the summer months and it’s in a small container. If you suspect an insect or disease, ask for a Rosarian on the Master Gardener helpline, describe the problem you are having with your roses and follow their advice.

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Roots of Trees Follow the Water in the Desert

Leave a Comment / big trees vs small trees, rootw, water /

Q. You posted pictures about watering with the depth of a plants root system. How do trees survive in lawns then? Suggested root depth of different plants and how much water to give them. This makes it easier to see that taller plants have deeper roots and need to be watered as such. As the roots get deeper they also get wider. This is why big trees use more water than little trees.  https://wateruseitwisely.com/saving-water-outdoors/plant-watering-guide/ A. Some trees survive in lawns and others don’t. As a rule of thumb, mesic (nondesert) trees will survive in lawns while xeric (desert) trees will not. For instance, ash trees (mesic) will survive in a lawn. Xeric (desert) trees will die if they receive water too often. Xeric trees such as Foothills Palo Verde will struggle in a lawn. Mesic trees are better suited for lawn areas than xeric trees. Roots of trees will go where there is plenty of water even if it’s in you or your neighbor’s yard. It goes without saying that large trees should not be planted close to walls. Plants are lazy, including their roots. Roots grow best where can get water mixed with air and get it the easiest. That concept pertains to both mesic and xeric trees. Daily watering during the summer means the roots of (mostly) mesic trees growing in a lawn area will have roots all through the soil surface. There they can get a mixture of both air and water the easiest. Roots growing in lawns well head to the surface of the lawn because that’s where they find a good mixture of air, water, and fertilizer. Removing the lawn also removes this distribution of water and air. Instead, these trees must survive on the water provided through drip emitters. That is a change from watering the lawn to watering shrubs. Is that enough water? Is the water provided in the right distribution? Is the water provided to the tree in the right spots? You will find out usually next summer when it gets hot. By the way, surface mulch (rock or wood chips) helps stop the water from evaporating from the soil during the heat of the day. Golf course superintendents well water new trees with a water truck even if they’re growing in grass. Besides water, roots of tall pine trees provide stability for the tree during wind. A general rule of thumb is to water deeply according to its height. For instance, tall trees growing without a lawn should be watered to a depth of 3 feet to provide the tree stability during windy weather.

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How to Get Rid of Snails in a Lawn

Leave a Comment / Light, slugs lawns, snail lawns, water /

Q. I have some snails in my lawn. How do I get rid of them? Snails like it wet and darker than most lawns. A. The best way to control snails (or slugs) in lawns is to give the lawn more light. Snails hate light but they like to eat!  Snails and slugs eat young plants and microscopic plants such as “large enough to see” algae. The worst situation for snails and slugs is lawns growing under trees producing shade. The bigger and denser the tree gets, the more shade it produces. Dappled shade produced by the branches of trees may need to be thinned if it gets too dense. Snails and slugs hate sunlight, prefer shade, and wet soil. Right now there is enough light for the lawn as well as snails and slugs….if the lawn is kept wet. In cases like that, get rid of the lawn, or both, but in the desert never favor the lawn over the tree. A good-looking fescue lawn uses a lot more water than nearly any tree and usually requires daily applications of water in the summer. Fescue lawns in the shade of a tree might still need 6 or more feet of water annually to look good. Many of our trees in full sun will need anywhere from two to 5 feet of water applied under their canopy. Xeric trees like acacia need less water, annually, than mesic trees like pistache or vitex. Snails and slugs in lawns There are baits made for snails and slugs. Those baits usually contain iron phosphate which is low in human toxicity. But it is a pesticide. Sluggo is the old tried and true chemical control for snails and slugs. If you are into organics, then you might not want to use Sluggo. Your only options are to increase the light and trapping. During times of high light levels snails and slugs look for places to “hide” so laying out boards or other places so they can hide during the day provide places where they “collect”. Their numbers can be reduced if you are willing to dispose of them after they collect during the day such as under something.

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Temperate Fruit Trees Like it Colder and Moist

Leave a Comment / cool weather, fruit trees, soil organics, temperate /

Q. I was in Moab, Utah, when I ran across this apricot tree. It’s doing very well. I’m guessing the reason they are doing so well is because of the high organic levels in the soil and cooler temperatures? Temperate fruit trees like apricot, peach, nectarine, plum and apple prefer cooler weather that elevation provides, organics in the soil, and watering like any other mesic tree. A. You’re right. Fruit trees prefer to grow in soils with higher organics than most desert soils unless those desert soils were “farmed” and extra water was needed for farming. Fruit trees also prefer to grow in cooler temperatures than provided by hot deserts. At about 4000 feet of elevation, the Moab area is higher in elevation, so it has cooler temperatures than our 2000 to 3000 foot elevations. Growing of citrus though, in either location, is borderline. Moab is still worse than our 2000 feet of elevation. Neither place is like Yuma or Riverside for citrus.

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Vitex or Monk’s Pepper is Not Xeric but Mesic

Leave a Comment / low water use, mesic, small tree, vitex /

Q. Our vitex has done well for over 20 years but it is starting to thin out. What gives? Vitex or Monk’s Pepper tree is mesic in its water use. Similar to oleander, it prefers to grow under mesic conditions (can handle a lawn for instance) but can also handles dry soil, to an extent. It prefers a fruit tree water environment so it can handle a  well-drained lawn. A. Hard to get blue flowers anywhere. Well Vitex, or Monk’s pepper, is a mesic tree that can have blue or white flowers. Yes, it is a mesic tree and not from the desert but it still is considered low in its water use. It is from Mediterranean regions like oleander and European olive. But it’s one of those strange “cats” that doesn’t like poorly drained lawns. It can’t handle drainage problems very well. 20 foot tree for the Phoenix area That may be the source of your problem with that tree. If the tree was planted in a low spot and, if all this rain added even more water to this low spot, on top of your irrigations, then water-soaked roots during the heat may be the source of your problem. Summer heat is more of a problem than cold weather regarding rotting roots. Recommendations but be careful planting in the desert, its different I was reading recently that vitex can be a short-lived tree. 20 years was the maximum life it was given in this reference. I don’t know if I agree, but you can winter prune it and extend its life. Trees, particularly small trees like vitex, can have an extended life by heavily pruning it in the winter. Many trees have a “root to shoot” ratio and the new growth will come back like gangbusters until that old root to shoot ratio is reached. Contrasting the information above, adding some compost to the soil at planting time can will make this tree live longer. Don’t be afraid of doing this. Amend the soil with compost at planting, water it like you would any other landscape tree. Prune it so that the trunk shades itself. Lightly fertilize it in the early spring with a fertilizer containing lots of nutrients including nitrogen.

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