April showers bring May flowers. And weeds. We refer to plants we don’t want as weeds. They pop up in locations where they don’t belong. They compete with the plants we actually want for sunlight, water and nutrients. In other parts of your yard, weeds look unsightly and can become a nuisance.
Control Weeds Before They Germinate
Since weed seeds need the right combination of soil temperature, water and sunlight to germinate and grow, weed control begins by creating undesirable growing conditions.
For a variety of reasons, including health and groundwater protection, turn first to non-chemical options for weed control. Spread a layer of mulch over the soil, especially on vegetable gardens and flower beds to also add organic matter and slow soil evaporation. A layer of rock or bark will have the same effect of blocking sunlight.
Chemical treatments are typical for cost-effectively managing weeds in residential parks and common areas. ELS applies seasonal pre-emergence residual herbicides for long-lasting weed management. Some pre-emergence products are available to homeowners for residential use.
Eliminate Weeds After They Emerge
For the weeds that nevertheless emerge, you can purchase various post-emergence weed killer products. Or, simply hand-pull or hoe the young weeds before they flower and set a new seed cycle. Applying simple household staples, like white vinegar, diluted rubbing alcohol or boiling water, are also effective methods for killing weeds. Just be careful not to accidentally damage the plants you wish to keep. YouTube videos are a good source for further instructions.
Weed Control in Turf Areas
If you have a lawn, this means that the best prevention against weeds is keeping your turfgrass dense and healthy enough to choke out weeds. Be sure to mow your variety of turf to its recommended seasonal heights and frequencies. Maintain turf vigor with routine, seasonal fertilization, aeration, and infrequent, deep irrigation.
If you choose to apply a pre-emergence residual herbicide on turfgrass at home, late autumn and early spring are generally the best times of year in Central Arizona. But plan ahead, because there are two different types of pre-emergence herbicides available for residential lawns, each with a different mode of action. Select the correct type and then follow all package directions carefully.
You know the saying “April showers bring May flowers?” Well, in Arizona this year it’s more like “March showers bring April flowers.” After all the storms last month, you probably noticed if there were any weaknesses in your yard’s drainage system.
Water follows gravity.
Remember that water follows gravity, until it reaches the lowest point, where it collects. It is these low points in your landscape that you need to address with a drainage solution when water becomes a problem. For example, your standing water following rains may breed mosquitoes, or overwatering land above a shallow water table may cause flooding. Here are some solutions to prevent standing water and drainage problems:
Dig a swale
Help water continue to flow by digging a swale that pitches downward from your current low point to an even lower point on your property. A finished swale might be a long, shallow trench finished with small rocks and plantings along it, for example, to help prevent soil erosion.
Add or extend gutters and downspouts
Add gutters along the edges of your roof to catch and channel rainwater down through downspouts. Trench in additional drainpipe lines to carry water even further, from your downspouts and away from valuable structures, like your house, into your landscape or toward storm drains in the street, for example.
As groundwater in the southwest becomes increasingly scarce, and more expensive, many homeowners will join the ranks of rainwater harvesters. Most often, this simple technique involves running water from gutters along the perimeter of your house into barrels or tanks with spigots or submersible pumps for storage and later use.
Plant a rain garden
If you have a low point in your garden that fills with water but doesn’t cause any immediate problems, you can take another approach and transform it into a rain garden or a focal area for your yard. Dig down and place a layer of rocks or add a liner to create a natural pond. Or, find native plants that thrive in that spot. It may take some experimentation because your plant choices will be guided by the size of the wet area, how quickly water percolates naturally into the soil, and how much sun the area gets.
Trench in a French drain to move water quickly and efficiently away from a structure or from any point on your property to an adequate drainage area. A French drain is most often made from connected lengths of perforated, flexible tubing sheathed in porous landscape fabric, which allows water to seep out without debris flowing into the pipe. Keep in mind that over time, you may still need to dig out and rebuild your drain if it becomes clogged.
If the area where water pools also happens to be the lowest point on your property, you may have no other choice than to build a dry well in that spot. A dry well serves as the endpoint in a drainage system. At its most basic, it can be a man-made pit filled with gravel, dug to a width and depth commensurate with the volume of water that collects at that point. Often covered by soil and turf or mulch on the surface, the large pore spaces between the stones allow large volumes of water to pass down deeply into the soil. Dry wells are the most common fix for soggy areas in parks and recreational turf.
There may be other causes for your water drainage problems that may be more complicated to resolve. For example, your land may not have enough pitch, your soil may be compacted, or pavements and hardscapes may be impeding water runoff. Consult with a residential drainage engineer for help with these types of problems.
In the ELS Enhancements Division, we are pros at designing and installing drainage systems and performing drainage repairs for homeowners associations and commercial properties Valley wide. Invite ELS to care for your commercial landscape by sending email to [email protected].
When it comes to fertilizing plants, you can usually find your tree, shrub, and garden fertilizers at any nursery or hardware store, each one specified for all sorts of potential uses and purposes. But for many reasons, turf fertilizer is much less clearly understood by the general populace. What makes turf fertilizer different from other fertilizers, if anything?
Fertilizers, at the most basic level, are collections of nutrients that plants need in addition to water, sunlight, and carbon dioxide, in order to thrive. A “complete” fertilizer is one that contains each of the three most important elements for healthy plants: nitrogen, phosphorous, and potassium. Most of the liquid and granular fertilizer for trees, shrubs, and herbs will be some formula of a complete fertilizer. The ratio, typically written as (Nitrogen %) – (Phosphorous %) – (Potassium %), is important to note on any container, because different regions have soils with different amounts of each of these compounds. Additionally, every species of plant uses up its mineral supply at a different rate.
The Needs of Arizona Grass
The Arizona soil found in the Valley is known for being almost completely void of natural Nitrogen, and it just so happens that Nitrogen is the nutrient that grasses tend to use up extremely quickly. If your grass is looking sad, with patches of thinning or discolored foliage, there’s a high chance that your turf is running out of usable Nitrogen.
In order to ensure a good supply of Nitrogen for your grass, ELS typically recommends the use of Ammonium Sulfate. Ammonium Sulfate is a chemical compound that is not a “complete” fertilizer, but rather a nutrient that supplies exclusively nitrogen to the soil with the fertilizer ratio 21-0-0. We follow the Maricopa County Cooperative Extension’s recommendation of applying ½ – 1 pound of Ammonium Sulfate per 1,000 square feet of turf space, depending on how deficient the grass appears to be. The same ratio is recommended for your personal backyard spaces as well. For example, if you have 500 square feet of turf in your backyard, apply 0.25-0.5 pounds of 21-0-0 Ammonium Sulfate across the space, depending on how healthy your grass is looking.
How Often Do I Fertilize Arizona Turf?
Every yard space is different. Some yards have very poor soil drainage, some have more or less shade than others, some have more nitrogen in the soil than others. Because of this, you’ll have to adjust for how your grass behaves over the course of a year. The general recommendations, however, range from every four weeks to every eight weeks. The Maricopa County Cooperative Extension website with the University of Arizona offers a series of charts explaining the best fertilizing frequencies for different varieties and combinations of grass. Go to extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1817-2020.pdf to read the full explanation.
The most common grasses that follow rules for the examples provided are Winter Rye for the winter and Bermudagrass for the summer. Other, less common grass varieties may have slightly different fertilizer preferences, though these general rules pertain throughout most grasses.
Other Nutrients and Practices
While Nitrogen is the most important element to get into your grass, it’s not the only nutrient that could use an occasional boost. Sometimes, grass becomes deficient in iron, which leads to pale foliage and an overall sad look. To solve this, use iron chelate or other iron-filled supplements. The Arizona soil (and water supply) is often high in salts, which can clog up soil and hurt grass. For this, apply gypsum and “aerate” the soil using a tool called a “lawn aerator.” If you’ve recently overseeded, we recommend using a fertilizer that contains both Nitrogen and Phosphorous.
The ELS Maintenance Division is a group of experts who have been keeping turf spaces looking great around the Valley for nearly 50 years. If you have any questions or manage a community or commercial property that could use a new landscaping company, email us at [email protected] and we can get started.
Citrus trees have strong wood that requires minimal pruning. A healthy tree can bear the load of heavy fruit. A common misconception is that a heavily pruned citrus tree will result in new growth and improved fruit quality. In fact, the opposite is true; minimally pruned citrus trees can produce fruit that is of better quality than heavily pruned trees.
Spring is Citrus Pruning Season
If your citrus tree requires pruning, the best months in Arizona are February to April. Best is after the danger of frost has passed but before the tree flowers. Pruning between April and October can expose the tree to sunburn damage, and November to February exposes the tree to potential frost damage.
Regular Maintenance with Minimal Pruning
Citrus trees produce the least fruit in areas of the tree canopy that are most shaded. Thus, your citrus tree may only need to be pruned in the spring to thin out those deeply shaded sections inside the tree canopy, opening them up to sunlight for fruit production.
Year-round maintenance of citrus trees involves regularly snipping off suckers and removing branches that are weak, diseased or dead. As with other trees, a limb that crosses another should also be removed to prevent damage to and consequent disease in the other limbs it touches.
Citrus trees, like roses, are most often grafted varieties onto a base rootstock. Shoots growing up around the base of the trunk or in nearby soil are rootstock suckers that should be removed. They are characteristically thorny and will not produce the desired citrus variety.
Thorny, unproductive varietal branches higher up in the tree can also be removed as part of regular maintenance.
Protect Cuts with Paint
Especially for large cuts, protect the exposed citrus wood by painting it with a 50%/50% mix of latex paint and water. Never use an oil-based paint on citrus.
Want to know more about how you can maintain the investment in your landscape and improve its value? Call ELS at any time at (602)-243-1106 or fill out a request a bid form on our website at www.elslandscapeaz.com
Love your citrus trees even more by growing tastier fruits. There are steps you can take to make your citrus fruits taste better.
Fertilize for good-tasting fruit
Fertilizing your citrus tree correctly is the key to good-tasting fruit. Different citrus varieties require different amounts of fertilizer. For simplicity, use a citrus mix fertilizer to fertilize your citrus trees three times a year. Feed oranges, mandarins and grapefruit in January/February, March/April and May/June. Fertilize lemons and limes in January/February, March/April and August/September.
To calculate the right amount of fertilizer to apply to your trees, use this citrus tree fertilizer chart from University of Arizona Cooperative Extension. Always follow package instructions carefully.
Give your tree enough water
Properly watering your tree is the next most important factor for growing good fruit. Ideally, you would water your citrus tree deeply and evenly, at times when a moisture meter reads moist at 6 inches below the soil surface. This method accounts for the water-holding capacity of your specific soil and avoids detrimental salt buildup.
Generally, citrus trees consume more water in spring than in fall. Different varieties of citrus trees have different needs. To give you an idea, grapefruit and lemon trees require 20% more water than orange trees, while mandarins require 10% less, according to University of Arizona research. Also noteworthy is that citrus trees planted in grass or with ground cover need 20% more water than trees in bare soil. This is because the grass limits the amount of water that reaches the tree’s roots. Use the number of drip emitters with a flow rate that best matches your desired total water application rate (via frequency and duration) for your tree’s needs.
Both underwatering and overwatering can negatively affect citrus quality. Good practice is to learn from this irrigating citrus trees guide how much water your citrus tree variety needs, and then watch your tree for signs of water stress in dry periods and limit overwatering during wet weather.
Other issues that can affect your fruit quality
If you are applying the right amount of fertilizer and water and your fruit still tastes bad, you may have other issues with your tree. Since most commercially available citrus trees are grafted onto rootstock, it’s possible that the part of your tree producing bad-tasting fruit could be a growing from the rootstock instead of from above the graft, which is a thicker, scarred section of trunk near the base of the tree.
Another good clue is that sucker branches growing from the rootstock usually have more spines than the branches growing from above the graft (also called the bud union). Suckers should always be pruned off. If a sucker grew into a mature leader on your citrus tree, that part of the tree will never produce good fruit, and you probably need a new tree.
Soil and water salinity can also affect the quality of your citrus fruit. Refer to our blog on soil testing for more information on laboratories that can measure salts in your soil or water.
It’s also possible your citrus tree has a disease. You can consult with a nursery professional or local cooperative extension office about the various symptoms your tree is showing.
For more expert insights on growing and caring for thriving trees, invite ELS to care for your commercial landscape by sending email to [email protected].
Most of us grow up hearing our parents yell at us that money doesn’t grow on trees. The sassiest of us called them liars because money is paper, and paper comes from trees. What is indisputable, however, is that trees are tangible assets in the urban landscape that increase in value over time. Generally, the bigger and older the tree, the more valuable it is.
Economic and Ecological Worth
To assess the value of a tree, let’s first ask whether we are after its economic or ecologic worth. Economically speaking, one measure is a tree’s perceived contribution to the value of the property on which it is located. Other economic benefits of well-placed trees include providing protection from the weather. Tree canopies provide shade from the sun, and evapotranspiration cools the surrounding air. Tree canopies can slow down winds and reduce the amount of heat a building loses, particularly through its windows. For a homeowner, that sun and wind protection can add up to real savings from lower cooling and heating costs.
A tree’s worth in ecologic terms is even more interesting. Arborists and other scientists geek out on measures that include stormwater runoff interception, energy savings, air quality improvement and CO2 reductions. Trees serve to control urban pollution by reducing stormwater runoff and are considered a rainwater harvesting technique. They intercept and hold rain on their leaves, branches and bark, increasing soil infiltration and storage of rainwater through their roots. They also reduce soil erosion under their canopies by diverting and slowing rainfall before it strikes the soil.
How Trees Work For You
Trees phytoremediate water, taking in trace amounts of otherwise harmful chemicals from the soil and transforming them into less harmful substances that they use as nutrients or store in their tissues. Trees can reduce the level of air particulates and ozone because their leaves absorb ozone, nitrogen dioxide and sulfur dioxide and generate oxygen during photosynthesis. They can also reduce atmospheric carbon by sequestering CO2 in their roots, trunks, stems and leaves while they grow, and in wood products after they are harvested.
To quantify and predict the economic and ecological value of one or more trees, use the clever modeling tool from i-Tree Design. This tool uses the tree’s location, species, diameter and condition to let you model your built structures and predict the value of specific tree species over a 1 to 99-year period.
Still, we humans usually plant trees for far simpler reasons—reasons that are rooted in neither economic nor ecologic value. We simply like how they look. They add curb appeal, design interest and sometimes privacy to our yards. We like them for bearing fruit, seeds or nuts. We like how they flower or change color with the seasons. We enjoy them as a source of recreation, like for a tree house, a rope swing or a hammock. And we admire how they are the simplest of homes, supporting local ecosystems of bees, birds and squirrels.
Whatever the value you desire or derive, invest in your landscape and property through proper tree selection, placement, pruning and nourishment.
Soil testing is a good way to assess the health of your soil and make any necessary improvements to soil fertility for more productive plants. Soil testing provides a snapshot of your soil’s current nutritional and material composition.
A big factor in your test will be the pH (acidity/alkalinity) level of your soil, which affects whether or not nutrients already present in your soil are available to your plants. Search the web for “soil pH and nutrient availability” images, which illustrate how pH corrections can improve what your plants access.
There are basic self-test kits available in garden centers and home improvement stores that can be helpful in measuring pH and for identifying nitrogen, phosphorous or potassium (NPK) deficiencies. Or, you can submit a sample to an independent laboratory for a more detailed report that can including other micro- and macronutrients, as well as cation exchange capacity (CEC), organic matter content, and soil structure. Here are the basic soil sampling steps to get your soil analyzed.
Collect a representative sample
From the area you wish to sample, like a planter bed, vegetable garden, lawn, or even a single pot, create a composite sample of the area’s soil. Use a professional soil probe or dig down 6-8 inches into the root zone to collect several small soil samples. Deeper samples are useful for measuring salt buildup. Collect the samples when the soil is the driest and mix them together. Then, per your specific lab’s instructions, use a clean, dry bag or container to package up the consolidated sample, minus any plant roots or rocks.
Submit your consolidated sample for analysis
There are many choices for soil testing: home test kits from garden centers, test-by-mail services, cooperative extension services, or independent laboratories, which cater to agronomy industry professionals and whose reports can seem highly technical.
The lab you choose will give you specific instructions for submitting your sample for analysis. Follow the instructions carefully to ensure the accuracy of your results.
Understand your results
For many homeowners, this is sometimes the most intimidating step in the soil testing process. For most self-test kits, a color chart will help you read whether your pH and NPK levels are over, under or within range. Mail-order services generally include results together with written reports that help to explain the nutrient levels and advice for why and how to correct. Testing laboratories catering to industry often test for a broader range of micro- and macronutrients, but the reports may list numeric results with little interpretation. A good beginners’ resource for understanding soil test results is at https://extension.psu.edu/soil-test-results-whats-next-guide-for-homeowners.
Amend your soil
There are so many possible variations for what your soil remediation may involve that we cannot cover them here. Still, no matter your soil test results, adding organic matter to your soil is the best remedy for poor soil. The process may take several years to improve your soil, so start now by adding compost or top-layering with various organic matter like mulch, manure, grass clippings and leaf debris to decompose into your soil. You can even start making your own compost from kitchen peelings and plant debris. A good sign your soil is improving is an increase in earthworms and beneficial funghi, microbes and nematodes.
For immediate corrections to macronutrient NPK deficiencies, look to common fertilizers to correct for the levels you need. You will find the amendments you need at local garden centers. Follow package instructions carefully for proportions and mixing.
Everything is coming up roses. Here in the Valley, January is the ideal month for pruning roses. It’s also time to get your bare-root roses into the ground and to relocate any established roses planted in an unfavorable location.
Rose pruning season begins once the danger of frost has passed, when daytime temperatures are below 70 degrees Fahrenheit, and while roses have ceased blooming. Prune roses before Valentine’s Day, when temperatures rise and bud eyes swell with new growth.
Know your rose
The purpose of pruning roses is to stimulate new spring growth and to achieve the greatest number of quality blooms. Most roses respond best to drastic pruning, so don’t be nervous. It’s always best to first confirm the types of roses you have—hybrid tea, floribunda, miniature, climbing, rambling, groundcover, etc.—so you can prune your rose to its best potential shape and size. This article focuses on pruning bush roses like hybrid teas and floribundas.
Cut for shape
Begin by using sharp, clean loppers and pruning shears/secateurs sterilized with isopropyl (rubbing) alcohol to prevent spreading plant pathogens. For bush roses, the objective is to achieve a vase-shaped plant (open in the center) and to have 5-12 remaining canes that are roughly knee height, 18-24 inches tall; more vigorous, established plants may have more canes.
While you are cutting, take note of discolored or diseased leaves or insects present to properly address any problems. Seal cuts with commercial cut sealant or school glue. Lastly, clear all clippings from underneath the rose to prevent mildew and disease.
What to prune in winter
Here are general rules of thumb for what to remove in the pruning process:
At least one quarter to one third, but no more than one half, of the previous year’s growth
Dead or diseased canes
Crossing, rubbing canes
Limbs less than the thickness of a pencil
Old, unproductive canes
Suckers below the graft union (on hybrid teas)
What to prune in other seasons
At other times of the year, keep your roses in shape by snipping off spent blooms just above the next lowest leaflet of five leaves (i.e., deadheading) and by removing any dead or diseased canes.
Love trees but hate the mess they make? In this month’s post, we are featuring desert-adapted evergreen trees you can enjoy in your Arizona landscape, with minimal maintenance. Although it’s rare for trees to produce zero litter, you can count on non-deciduous trees to produce minimal debris.
As always, match the right tree to the right location to maximize your enjoyment of the trees you select.
To help you select the most suitable trees for your landscape, we have listed the main characteristics of some of our favorite low-litter species, followed by more detailed descriptions.
Willow acacia (Acaciasalicina): 30’ high, 20’ wide; shade tree for narrow spaces
Detailed Descriptions of Low-Litter Trees for Arizona Landscapes
The African sumac (Rhus lancea) is an evergreen tree with a wide, rounded canopy that spreads to 20-30 feet high and wide. It features dark brown, cracked bark and 4-inch-long leaves that are dark green on top and silver underneath. On female trees, its yellow spring flowers produce green berries that many bird species enjoy. It tolerates heat and poor, dry, salty soil.
Arizona rosewood (Vauquelinia californica) trees are slow-growing shrubby evergreens that grow to about 10 feet tall. They feature dull, dark green serrated leaves and clusters of short-blooming white flowers between late April and early May. Performing best above 2,500 feet in elevation, Arizona rosewood grows in partial or full sun but yellows in the hottest Valley temperatures.
The Brazilian pepper tree (Schinus terebinthifolius) is a dense shrub that can be pruned into a small tree that can reach 30-40 feet high and 20-30 feet wide. The Brazilian pepper features clusters of flowers 2-3 inches long in a long flowering season, September to November, with glossy fruits that ripen to red clusters of peppery edible berries.
Blue Arizona cypress (Hesperocyparis arizonica, formerly Cupressus arizonica) trees are native to the southwestern U.S. but do not always perform well below 6,000 feet in elevation. They are fast-growing, reaching 40 feet in height and 30 feet in width. Planted together, they can form a windbreak or a privacy screen along fence lines.
Italian cypress (Cupressus sempervirens) trees require direct sunlight and are drought-tolerant. Their vertical, conical shape makes a strong, vertical focal point, reaching 30-50 feet high and 5-8 feet wide. Cypress trees shed small amounts when the old, interior growth ages. They can be planted in a row to provide an imposing wind break or natural barrier.
The carob or locust bean tree (Ceratonia siliqua) is an evergreen native to the Mediterranean and the Middle East. Reaching 30-40 feet tall and 30-40 feet at maturity after 20-50 years, it features a broad, hemispherical crown, sturdy branches, and a deep taproot. Female and some bisexual varieties produce summer flowers and 6-inch-long edible seed pods that taste like chocolate.
Cascalote (Caesalpinia cacalaco) or Mexican bushbird is a native Mexican evergreen tree that likes full sun and grows in a vase-shaped form to 20 feet tall and 15 feet wide. It grows in full sun in well-drained soil and has bright green leaves and seed pods. It attracts hummingbirds with its very showy yellow flower spikes, winter through spring.
Cherry laurel (Prunus laurocerasus) is an evergreen shrub or small tree is useful as a privacy screen. It attracts butterflies and bees with its fragrant, cream-colored flowers, followed by red berries that attract many bird species. It grows 20-25 feet tall and 20-30 feet wide but can be trained into any shape. The cherry laurel tolerates full sun and full shade but performs best in part shade.
Chinese pistache (Pistacia chinensis) is a large tree with showy orange and red leaves in late fall which it drops all at once, once a year. Chinese pistache is dioecious, which means each tree is either a male that produces pollen that has little or no allergenic qualities, or a female that produces inedible berries that are attractive to birds. It is fast-growing and enjoys full sun and fast-draining soil. At maturity, it reaches 30-35 feet in height and 20-30 feet in width and is very drought-, wind-, and heat-tolerant.
Indian laurel fig
Indian laurel fig (Ficus nitida), also called Chinese banyan, is a fast-growing, medium-sized evergreen, native to Asia and Hawaii. It features tropical-looking foliage that is glossy and dense. Its spring flowers are inconspicuous. It tolerates air pollution and grows 20-30 feet high and wide.
Desert ironwood (Olneya tesota) is native Sonoran Desert evergreens. The oldest know specimen is over 2,000 years old. It features green leaves and lavender flowers in late spring that mature into bright red berries. Ironwood can reach 15-30 feet tall, 15-20 feet wide, and can grow in rocky, infertile soil, but it requires full sun and 6 inches or more of annual rainfall. Its wood contains compounds known to have anti-inflammatory properties.
Leather leaf acacia
Leather leaf acacia (Acacia craspedocarpa) is a dense evergreen shrub that can be pruned to a small tree that grows slowly to 10-13 feet. Its rounded leaf petioles are silver and leathery. Native to Australia, it grows in full or reflected sun and blooms with yellow puffy flowers, spring to summer. It tolerates poor, dry, rocky soil and is frost resistant to 18 degrees Fahrenheit.
The live oak (Quercus virginiana) tree is a broad, evergreen shade tree. It differs from typical oaks in that it is a medium-fast grower that is drought tolerant once established. It grows in full sun, 40-80 feet tall, spreading 60-100 feet wide. It features large, dense foliage for deep shade. It has subtle green flowers in spring.
The mastic tree (Pistacia lentiscus) grows as a large shrub or small tree that is 15-20 feet high and 20-30 feet wide. It can be pruned into topiary shapes, and its resin can be chewed to clean teeth. It tolerates poor soil and hot, dry growing conditions. Spring flowers develop into small, red berries that ripen to black.
The mulga acacia tree (Acacia aneura) is native to Africa, Asia, Australia and North America. With silver, needle-like foliage and gold flowers in mid- to late summer, the mulga is great for color contrast. Mulgas are slow growers but reach 15-30 feet in height and 15-20 feet in width and have roots that grow to 35 feet. Mulgas lose their leaves only in extreme drought conditions.
Neem tree (Azadirachta indica) is an evergreen tree native to the Indian subcontinent. It is widely used for medicinal properties and in cosmetics, producing white or yellow flowers in spring that develop into vibrant yellow fruit that attract birds and insects. It grows 30-40 feet tall and 10-20 feet wide. A neem tree is sensitive to frost and needs frost protection.
Red cap gum
Red cap gum (Eucalyptus erythrocorys) is a fast-growing Australian-native evergreen that likes full sun. It has 4-inch-long silver-blue leaves and grows to 30 feet high and 25 feet wide, serving as an effective screen. It features red buds followed by yellow clusters in the summer.
Silk floss tree (Chorisia speciosa) is a lush, dense tree, native to Brazil and Argentina. It likes full sun and grows to 30-60 feet in height and 20-30 feet in width. It features an eye-catching spiny trunk and deep green 5-inch-wide leaves. In the fall, the tree drops its leaves and produces showy, pink, lily-like flowers, and then produces seeds and cotton-like fibers in the seed capsules.
Texas mountain laurel
Texas mountain laurel (Dermatophyllum secundiflorum, formerly Sophora secundiflora) is a small, shrubby evergreen native to the Chihuahuan Desert. It features dark green leaves and beautiful hanging clusters of purple flowers in spring. It is frost-tolerant and grows in full sun to 8 feet tall and 6 feet wide.
The Texas olive (Cordia boisseri) is a medium-sized evergreen that features multiple trunks and a growing size of 40 feet high and 25 feet wide. It has narrow green leaves and produces white blossoms from February to April that attract hummingbirds. Its fruits are edible, but the seeds have been known to cause serious illness in humans. It prefers moderate summer temperatures but can withstand freezing winter temperatures.
The weeping myall (Acacia pendula) is an Australian native evergreen that resembles a weeping willow, with graceful, draping grey-green foliage. It creates dense shade and features pale yellow balls in spring and winter. Frost- and drought-tolerant, the weeping myall needs full sun and is slow-growing, reaching 15-30 feet in height and 15-25 feet in width at maturity.
The willow acacia (Acaciasalicina), an evergreen native to Australia, is an excellent shade tree for narrow spaces. It likes full sun and grows to 30 feet high and 20 feet wide. Its spring blossoms are puffy and cream-colored.
With a little knowledge and planning, you can protect your landscape plants—and your investment—from frost damage. In Arizona, we can get frosts from about Thanksgiving to Valentine’s Day.
As a rule of thumb, it’s important to know that younger, dehydrated and actively growing or flowering plants are most at risk for frost damage.
As the weather cools, plants naturally “harden off” by slowing their new growth and ceasing blooms. Therefore, it’s important to protect landscape plants both from frost and from budding or blooming too soon before the danger of frost has passed. Still, the faster the drop in temperature, the lower the temperature and the longer the exposure, the more at risk any plant is to frost damage.
Select frost-tolerant plants. Native plants will fare the best in all temperatures, whereas tropical plants may suffer in the cold. To find a plant’s temperature hardiness, search https://www.amwua.org/plants, AMWUA’s Plants for the Arizona Desert
Keep soil appropriately moist. Although water requirements for different plant species vary year-round, it’s important to know that frost damage can be more severe in dehydrated plants. And, although it seems counterintuitive, it’s beneficial to water plants before a predicted frost because water releases energy in the form of heat when it cools, thereby warming the foliage above ground.
Cover at night. Each night a frost is predicted, drape over sensitive plants a cloth that touches the ground, allowing warmth from the ground to fill the resulting dome structure. Remove the cover in the morning so the ground warms up again the next day. If you need to keep plants covered for multiple days, look for purpose-designed frost cloths or frost blankets. Do not use plastic because it freezes.
Choose warm locations. Frost-sensitive plants will be better protected when they are sheltered, when they are exposed to full daytime sun (south and west sun are best) or when they are located near rocks, walls or benches, which radiate daytime warmth.
Resist pruning. Pruning stimulates new plant growth, which can be even more susceptible to frost. Do not prune frost-damaged plants until spring, after the danger of frost has passed.
Wrap tree trunks. For young citrus and other frost-sensitive trees, loosely wrap the trunk from the lowest foliage down to the ground using multiple layers. Leave wrapped for the winter.
Add heat. Add incandescent lights or string lights below the foliage because their heat radiates upward. LED lights do not generate sufficient heat for this purpose.
If the weather forecast shows low nighttime temperatures, refer back to these 7 tips to prevent frost damage to your sensitive plants. You’ll be protecting their shape and giving them a head start on budding and blooming when spring comes.