Preparing for an Arizona Winter

Frost season in Phoenix typically runs mid-November through February. The frequency and intensity of frost varies in both rural and metro areas for a number of reasons including elevation and population density. Our cooler weather provides us with the opportunity to conserve one of the desert’s most precious resources; water.

Water Savings

From roughly Thanksgiving to the end of February, most desert and desert adapted plants do not require water. You can choose to reduce your watering schedule to just a day or two a week or even turn the controller off completely! If you choose to turn your controller off completely, it’s important to continually monitor your lawn for signs of stress and provide water when necessary  Once night time temperatures return to the upper 70s, you will want to start watering again. Since most plants go dormant during this time of year and you can find the emitter a little easier than when plants are blooming, late winter/early spring is an excellent time to check your irrigation system for any faults or malfunctions. Turn your controller on one zone at a time and verify that each irrigation head is functioning properly.

Protect your Backflow

When temperatures dip below 32 degrees Fahrenheit  your backflow is at risk for damage from freezing water that sits in the unit. Usually, the easiest way to protect your backflow preventer is to cover it with a towel or blanket, as pictured, on the nights that temperatures are projected to drop below freezing.  You can also choose to drain the water from your backflow if you are concerned about prolonged freezing temperatures or plan to be gone for several nights. For more information on how to winterize your home sprinkler system including your backflow, please visit the Colorado State University Extension website.

Frost Protection for your Plants

Cover plants susceptible to frost-damage with cloth towels, blankets, sheets or paper/cardboard boxes to insulate them. Plastic is not recommended for plant cover. Drape the paper or cloth all the way to the ground to help trap heat radiating from the ground under the cover. A nursery can help you identify material made specifically for covering plants. Remove the cover after sunrise each morning or when the temperature reaches 35 degrees.

Plants not native to the Southwest are most at risk for frost damage. These plants include Bougainvillea, Lantana, Winter Annuals and others. For cacti such as Mexican Fencepost, covering the tops of the posts with an old t-shirt, foam cup or wash cloth can help prevent frost damage. Watering plants the night before a frost can also help them stay warmer. Dehydrated plants are more susceptible to frost damage.

To Prune or Not to Prune?

If frost impacts your plant material, it is optimal to wait until the threat of frost has subsided to prune frost-damaged plants. Pruning away frost damage too early can result in additional damage to the plant if it is hit by frost again. New and un-established shrubs or ground cover plants are more susceptible to permanent damage and could be lost due to cold weather. Established plants with a sustainable root system can handle minimal pruning for aesthetic reasons throughout frost season.

When it comes to trees, some species like Ficus are particularly sensitive to frost damage. Many smaller trees may be lost all together and, unless particularly protected, significant portions of the larger trees may be severely damaged due to hard frosts. While it is hard to be patient, it is best to wait to see if new growth will come back. If you decide to prune the dead tissue, it will take years before it grows to its original size. If you decide to leave it, the green will eventually fill in, but you’ll be looking at brown dead tissue for several years.

No matter what steps you follow to prepare for cooler weather, it’s important to take proactive measures to prevent any loss of plant material, irrigation components and ultimately, your money, during the winter months.

For more information on desert landscape and plant care, check out Arizona Cooperative Extension. If you reside elsewhere in the southwest, contact your local Cooperative Extension office.


When the winter and summer rains are done, the Sonoran Desert comes alive with bright and vibrant wildflowers. To achieve this natural looking landscape you will need to know when and how to plant your wildflower seeds.wildflowercombo


Before planting, it is best to loosen the soil in the area you want your wildflowers to bloom. This enhances soil aeration and increases water permeability.

Time To Plant

The optimum soil temperatures needed for seed germination vary depending on species. Spring-blooming annuals such as poppies, lupines and bluebells should be planted October through December. Summer-blooming annuals such as Arizona poppy and devil’s claw can be planted in late spring or early summer. Seed planting also varies for perennials. Penstemons, evening primroses and blackfoot daisy germinate more readily in the fall. Summer growers such as datura, desert senna and desert plumbago germinate in late spring to early summer.


After you have prepared your soil, level the bed with a rake to create an even surface on which to sow your seeds. Your flowers will look more natural if the seed is broadcast randomly and evenly over the prepared beds rather than planted in rows. It also helps if you mix your seeds with sand or fine dirt for ease in broadcasting them more evenly. Read package instructions as some seeds may need treatment prior to sowing.


Dsc00043Water the seeds daily with a fine mist sprayer, keeping the soil evenly moist until they emerge from the ground. Once the seedlings emerge, water every other day, keeping a careful watch on the small plants and not allowing them to dry out. Once the plants are showing four to five leaves and are well established, a deep soaking once a week or less often will suffice.

For more information on wildflowers, please go to:



IMG_6087Have you ever walked by a shrub that looked like it was covered with spaghetti? No, it’s not cloudy with a chance of meatballs – the plant is infected with a weed called Dodder. Dodder is a parasitic vine that is extremely difficult to eradicate. What is a parasitic vine? It’s a weed that depends on a host plant for all of its needs.

How to Identify Dodder

To spot Dodder, look for long, slender, thread like stems that kind of look like spaghetti. It may also have bell shaped flowers that are cream colored. Dodder is a tricky weed because it grows and branches out to nearby plants very easily. Because of this ability, it often looks like a matted mess covering up a whole plant. The more vines there are, the more energy that is removed from the host plant. The loss of nutrients to the Dodder combined with the loss of light from the matted weeds can cause major damage to the host plant.

IMG_6077Dodder Challenges

One of the biggest challenges with Dodder is its seeds. Dodder is a flowering plant and its flowers will produce thousands of seeds which, when mature, will fall to the soil below. The seeds have a very hard coat around them and stay dormant in the soil until the right conditions come around to sprout. When it comes to getting rid of a Dodder infestation, it is the seeds that cause the greatest headache, which is why prevention is so important.


At the first sign of Dodder, pull it off the plant and throw it away. Check the infestation site often because the weed may quickly regrow so it’s important to keep pulling. If you see Dodder soon after it has attached itself to a host, prune the infected portion of the host plant 1/8 to 1/4 inch below the point of the attachment, otherwise the dodder can regenerate. If the Dodder is attached to a shrub or tree, pruning is only helpful if it is confined to one or two branches. Removing any more than that will most likely cause major damage to the host shrub or tree.

Because Dodder is extremely difficult to destroy once it has taken over a plant, it is important to try to end the growth cycle. Use a pre-emergent herbicide like oryzaline that, when added to the soil under the infested plants, will kill the seed before it grows. Currently, there are no post-emergent herbicides that kill dodder without also killing the host plant. If the infestation is completely unmanageable, removal of the host plant with its attached dodder may be the easiest solution.

Care For Your Ocotillo

Ocotillo_ImageOcotillo, Fouquieria splendens, is a slow-growing plant native to the Southwest region. Boasting tall slender cane stalks that bloom with bright red-orange, trumpet shaped flowers, the Ocotillo is a popular desert landscape plant requiring little maintenance.

Ocotillo Characteristics

  • A mature plant typically reaches 12 feet high and 10 feet wide, but can grow much larger
  • Thrive in full sunlight and attract hummingbirds
  • Deciduous, meaning they shed their leaves through the winter months and leaf out after periods of sufficient soil moisture
  • Can tolerate low temperatures down to 10° F before suffering serious injury or damage
  • Red-orange flowers blossom in the Spring

Planting Your Ocotillo

Soil LineAccording to the University of Arizona’s Cooperative Extension, transplanting is best done March through May. Plant a bare-root Ocotillo in dry, loose, sandy soil with light to moderate amounts of organic content to ensure root development. If your Ocotillo is marked on the South side, it should be planted facing South. To help the ocotillo from falling over or blowing down in a storm, large stones may be placed over the root area (2-4 inches from the trunk). Ocotillos need full sunlight in open areas where surface water does not collect.

Little Maintenance Required

ocotilloThe Ocotillo is highly drought tolerant and considered a low-water-use plant. It will require irrigation after it has been planted. Avoid over watering the soil, as too much groundwater will cause the roots of the plant to rot. Instead, water by spraying the cane of the plant and keep the soil moist. Water newly planted Ocotillos once a day (typically for 10 minutes) and established Ocotillos every month or so.

The Arizona Municipal Water Users Association (AMWUA) recommends the “Do no harm” pruning method. Essentially, the best method of care for your Ocotillos is to only remove dead or diseased wood. This is particularly true for Ocotillos in the ground for less than three years.

Some degree of growth set-back is expected after planting. Wait patiently – these plants often look like they are dead, especially in periods of drought. With minimal care and watering, most Ocotillos will develop into attractive and healthy plants when left alone.

University of Arizona Cooperative Extension Office
AMWUA Landscape Plants for the Arizona Desert Guide

Cactus Care

Cactus LCWatering Guidelines

Cacti have an amazing ability to store water and adapt to new environments. Over-watering combined with poorly drained soil is a recipe for cacti to struggle. The soil should dry almost completely between watering cycles. Check the root zone about 2-3 inches below the surface. If the soil is still damp, wait until it is dry before applying more water. Regularly checking the root zone before watering gives you a good idea of what your plants’ unique watering needs are.

As a general rule, cacti planted in well drained soil can be watered every 10-14 days for one hour (based on using drip irrigation) during the summer months. That amount of time allows the soil to dry thoroughly between watering, yet gives the plant enough supplemental water to survive the heat. As daylight decreases in fall, water should be reduced. As nighttime temperatures drop below 60 degrees, turn off the water completely. Most cacti can survive on natural rainfall alone during winter months.

These watering guidelines apply to most cacti. The one exception is Saguaro cacti. Saguaros should never be watered. If you have a Saguaro that appears to be suffering, consult with your local nursery that specializes in selling cacti.


There is no need to apply fertilizer to cacti planted in the landscape. Cacti planted in pots do occasionally need some fertilizer. In that case, use tomato food (8-20-10) unless you can find specialized cactus fertilizer at a nursery. Apply the fertilizer once a month during the summer months only.

Cacti Challenges

Cacti suffer and often die from three main sources: soil borne pathogens, insects and animals. Pathogens, mostly fungi, affect cacti in many different ways. Normally you will see brown depressions form at the affected area. In some cases, the affected areas can be treated by a fungicide. If the disease has spread to the point where it is highly noticeable, it is better to remove the cactus before the disease spreads to neighboring plants. Proper watering is the key to preventing the spread of soil borne pathogens.

Proper watering also plays a key role in discouraging insects from damaging cacti. Insects are opportunistic and need moisture to survive. Saturating your soil with water is an open invitation to an insect.

Animals, particularly rabbits, find some varieties of cacti tasty and can cause significant damage. The best way to prevent animal damage is to limit access to the plants. Install wire mesh around cacti, especially while they are young. Or simply find a different location to plant your cacti.


Planting and Caring for New Plants

Whether you want to add new plants to your yard or you’re replacing plants you lost to winter’s freezing temperatures, now is the time to plant to give them the best chance of surviving the summer heat.

Shrub and Tree LandscapeIdeally, new plants should be installed when nighttime temperatures are over 55 degrees for a prolonged period of time and daytime temperatures are less than 90 degrees. For our desert landscape, plant replacement is most successful in the early spring because temperatures and humidity allow the plant to establish itself in its new environment before the harsher summer weather arrives. Certain tree species like acacia salicina and the desert willow demand spring planting because they establish new roots very slowly.

When choosing your new plants and trees, ask yourself these following questions:

Is it the right plant/tree for the right space?

How big is your plant or tree going to be in its mature size as it relates to its space? Does it have thorns that could grow into the common areas and sidewalks?  Do the roots have enough space to find the nutrients it needs? Expect trees to have root systems that reach out underground has far as its canopy extends.

What kind of light does it need?

The closer that the plant is to those hard surfaces like sidewalks and brick walls, the more sun and heat it will absorb. Be cautious of placing plants near these reflective surfaces.

How much water does it need?

Young plants will need more water as they root out looking for nutrients in the soil. Look for signs of distress like wilting or curling of leaves, leaves losing their color, and dead stems as signals of needing to water more. Also consider possibly using mulch or fertilizer to boost the young plant’s growth.

A young tree will need to have more emitters located near its trunk initially. These emitters will need to be moved from the trunk on a yearly basis to encourage the spread of the roots as the tree matures.


BougainvilleaThe Bougainvillea, a versatile, evergreen desert woody vine, flowers several times throughout the year and is native to the Brazilian coast. The most common type of Bougainvillea plant in the Southwest has vibrant reddish pink flowers; however some varieties have more pink, salmon or purple blooms. This resilient and drought tolerant plant grows in a variety of different manners, including climbing vines and bushes, and can be trained to grow in various shapes and in many different sized spaces.

Before the Frost Comes

During the fall months, balanced pruning is needed for your Bougainvillea plant. Pruning should be done to keep the plant from encroaching on walkways or to keep the plant within its boundaries. However, you want to make sure not to drastically prune before frost season so you do not expose sensitive parts of the plant to the freezing temperatures. When the frost blankets the ground, the large portions of the plant that remain will turn a brownish black color and the leaves will drop, leaving just the stick portion of the plant for the winter. If you prune your plant excessively in the fall, there will not be much of the plant left when the frost damage is pruned away next spring. To ready your plant for the winter months, stop watering it around Thanksgiving for the winter and start watering again around mid-February when the daytime temperatures return to the 80s.


In the colder months, it is recommended that you not prune your Bougainvillea plant to help protect it from frost damage. For younger plants, you may want to cover your Bougainvillea with a light cloth or sheet on nights when frost is a threat. If your plant suffers frost damage, you should wait to prune it until spring when the frost threat is gone since the damaged portions of the plants act as insulation for the rest of the plant throughout the winter.

When Spring Arrives

Now that the frost has gone, it is time to prune your Bougainvillea to ready it for the new growing season. You can choose to do a light prune, like you did in the fall and trim just the extremities of the plant or a hard prune which means you cut the plant down to almost the base to stimulate all new growth. When pruning, be sure to wear protective clothing as the Bougainvillea is a thorny plant. When daytime temperatures consistently reach the 80s again, you can begin regularly watering your plant material.

Planting New Bougainvillea

When installing a new Bougainvillea plant, you should keep a couple of things in mind. Since Bougainvillea can grow in a variety of space sizes, be sure to consider the fine root system of the plant and plant it in well-drained soils to prevent root rot. These plants prefer direct sunlight for at least 5 hours a day and because of the plants’ constant blooms, it might not be the best plant to plant near a pool.Bougainvillea After Trim

Bougainvillea Before TrimBougainvillea Cut Back in Fall