Category: trees in desert gardens

Best native shrubs for relentless desert heat

Here we are in September with weather that used to belong to July. With weather this hot it is too early to plant shrubs and trees in your garden. Wait until the daytime high air temperature is 90 degrees Fahrenheit or less. That 90F temperature is a useful indicator that the soil has cooled off enough. Hot soil can kill a newly installed plant within days.

Now, however, is not too early to plan adding tough native shrubs to help minimize the effects of the blistering heat next year.  (And it will be blistering hot next year. You can count on it, as the climate changes.)

While you may think “I need to plant big trees to cool my garden”, in fact, shrubs can definitely help by shading smaller areas and the lower sides of your home. Shrubs also keep the ground beneath them cooler and your overall garden at a lower temperature. The shade shrubs cast can create a haven for small wildlife like birds, lizards, bees and other insects.

So here are a few favorites, most are evergreen and all, but two, are native to the U.S. Southwest. (And those two are tough Aussies!)

1. Texas Ranger (Leucophyllum frutescens)

Also known Texas Sage, is a staple in desert landscaping due to its low water needs and striking silvery foliage. Imagine how glorious a hedge of these will look as this hardy shrub bursts into a display of purple blooms when the summer humidity gets high. It thrives in full sun and poor but well-drained soils, making it an ideal choice for low-maintenance gardens. Whatever you do, do not trim your Texas Ranger into a lollypop shape. It is naturally a loose, open, and graceful shrub that reaches up to 6 feet in height and will live for as long as 30 years. ProTip: trying to bring on blooms by watering the plant, won’t work.  It takes the increased humidity of the monsoon for the Texas Ranger to flower.

Desert Willow Chilopsis linearis

2. Desert Willow (Chilopsis linearis)

Desert Willow (Chilopsis linearis) can be grown as a small, messy tree or multi-trunk shrub. But messy as it is, the Desert Willow is popular because it will survive on its own with no extra water or fertilizer required.  Grows two to three feet a year and reaches a height of 15 to 20 feet and will live for over 40 years, if planted no higher than an elevation of 5,000 feet. It can be found in the wild in all the major Southwestern deserts from Chihuahuan to the Mojave to the Sonoran and the Colorado desert. As a desert native it needs little care and will produce red, pink, white, and purple flowers for months on end, but, I repeat, it is a messy tree dropping those long, brown seed pods for you to clean up. Now read about the next tree, a tidier hybrid of the Desert Willow.

3. Chitalpa trees (Chitalpa tashkentensis)

Chitalpa trees can grow as large, multi-stemmed shrub or a single-trunk tree. Unlike its cousin the Desert Willow, Chitalpa trees were created by scientists to be sterile and do not have those long, pointy seed pods. Their leaves are wider and create more shade. For that reason, the Chitalpa, like its cousin, is often planted as a street tree that blooms for months on end without supplemental watering. This hybrid thrives in endless sunshine and grows very fast to 30 feet tall. It’s said to live up to 150 years which seems a bit unlikely to me, but it you can be sure it will be growing where you plant it even after you are no longer gardening. Hummingbirds and bees love its pink or white orchid shaped flowers.

4. Jojoba (Simmondsia chinensis)

Jojoba (Simmondsia chinensis) has been an ignored shrub of the Sonoran Desert and Baja. The oil from the seeds was used for centuries by native Americans to treat skin conditions such as psoriasis and eczema.  A few decades ago, young women who were advocates of natural skin care “discovered” it and the oil was added to many skin and hair care products as a hydrating agent as well as having skin health benefits. But, skin care aside, it is simply a nicely shaped, round shrub that grows to a height of three to six feet with gray-green leaves year ‘round with seeds that go from green to dark brown. Oil is relatively easy to express from the seeds. It is highly drought-tolerant and reputed to live for decades.

5. Littleleaf Cordia (Cordia parvifolia)

Cordia parvifolia is a low maintenance plant which is not common in hot, dry gardens – but it should be. It is very drought tolerant once established. Ideally, it should be planted in locations with full sun and will produce large white flowers for months on end from early spring to fall with supplemental irrigation. This native of the Sonoran and Chihuahuan deserts is a dense shrub with arching branches that grow up to 6 feet tall and wide, making it suitable for hedges or as a standalone plant. You may have to call around to garden shops or plant nurseries to find it and you may end up finding it at a native plant nursery. In a pot it is disappointing, but plant it in the ground and this shrub with its white flowers becomes a beauty.

6. Feathery Cassia (Senna artemisioides)

Feathery Cassia, a native of Australia, is smaller shrub with feathery leaves that can tolerate very high temperatures. Known for its wispy, gray-green foliage and bright yellow flowers, which bloom in late winter and early spring, this plant provides seasonal color while maintaining year-round interest. Its flowers are also very fragrant attracting bees and other insects. Feathery Cassia grows up to three to four feet tall and wide, making it suitable for smaller spaces or as a border plant. It thrives in full sun and well-drained soils, needing little water beyond what falls from the sky once it is established.

7. Lantana (Lantana camara)

This native of the African tropics and popular in Australia, has spread around the world because it thrives in hot climates and blooms with colorful flowers for months on end. In the U.S. Southwest the Lantana camara, the upright version of this shrub, can become an attractive hedge. (In places like the damp U.S. SouthEAST it has become an invasive plant to be eradicated if possible.) Please note that for a hedge or a taller shrub you want to get the Lantana camara, not the low-growing, mounding Lantana montevidensis, also called trailing Lantana. Planted densely, as shown in the photo, the upright version will grow to 6 feet tall and as wide as 5 feet and can be trimmed into a tidy hedge. And as for flower colors — they seem to be endless! Mix them up.

8. Creosote (Larrea tridentata)

Why no photo for creosote? When doing research for this post, I asked the artificial intelligence ChatGPT for a list of native desert shrubs suitable for residential gardens to see how its list compared to mine. The first on its list was creosote. What?? Creosote is basically a weed in most Southwestern deserts. In Tucson there are actually neighborhoods with acres and acres of creosote “forests” dense with volunteer plants that are about 5 feet tall. They provide privacy to homes built in the back of the property decades ago, but no one planted the creosote bushes; they just grew. Creosote’s one claim to fame is that it/they can live for centuries. It’s true. New plants spring up from the roots of the older ones forming an ever-widening circle of creosote. One creosote circle in the Mojave was dated to 10,000 years old! Maybe one day ChatGPT will “read” this and realize that it gave bad advice. Don’t plant creosote.

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Growing a backyard orchard

Imagine stepping into your backyard and being greeted by the sight of thriving fruit trees ladened with succulent, sun-kissed fruits. A dream? Not at all. It takes a little planning and some digging but you can easily start a backyard orchard this weekend in your desert garden.

On left, green figs and on right, ripe peaches. Both would be delicious fresh from the tree in your garden and on your table. (Photo of peaches on tree by Czapp Botond on Unsplash.)

Not all fruit trees are created equal

First you need to select the right varieties suited to arid conditions in order to create a successful backyard orchard. Opt for drought-resistant and heat-tolerant species such as pomegranates, figs, quinces, citrus trees (like oranges and lemons), and stone fruits like nectarines, apricots, plums, and peaches. These varieties have adapted to thrive in the challenging conditions of a desert environment.

(Note that citrus trees do not do well in low desert locations like Phoenix. And fruiting olive trees and mulberries are banned in Las Vegas, NV and Pima County, AZ.)

If you want to branch out, consider adding nut trees like pecans to your orchard. Keep in mind, however, that pecan and other nut trees (and fig trees) grow very tall and may put the rest of your garden in the shade–literally–blocking out almost all sunlight.

Soil Preparation and Watering

Desert soil always poses challenges, so you need to start your mini-orchard by improving the soil structure with organic matter, such as compost. This should enhance water retention and nutrient levels. Adequate drainage is also crucial to prevent waterlogging, especially in desert climates where heavy rains can be sporadic but intense.

To install your fruit trees dig a hole that is only as deep as the root ball, and be sure that it is three times as wide. This will allow roots to spread out, grow faster, and anchor the tree better.

After the young fruit trees are installed it is important to set up a drip irrigation system to ensure a slow, steady release of water directly to the root zones, minimizing evaporation and wastage. Use mulch around the base of your fruit trees to further retain moisture and regulate soil temperature.

Protecting Against Extreme Temperatures

Desert climates are notorious for their extreme temperature fluctuations. To protect your new fruit trees consider installing shade cloth during the hottest parts of the day. It can be just something as simple as an old sheet or length of burlap draped over the top of the tree. As you can see in this photo from the Tucson Mission Garden, this cloth cover will shield the trees from the intense sun and reduce stress on them. Additionally, planting trees in locations that receive some natural shade during the day can provide relief from the harsh afternoon sun.

Pruning and Maintenance

Regular pruning is essential for shaping your backyard orchard and promoting healthy fruit production. Pruning regularly and tightly also lets you plant trees much closer together so you can grow more fruit. For example, nectarines only produce fruit on new growth so they should be pruned annually. On the other hand, pomegranates need almost zero attention. And fig trees, if left unpruned, will grow to 20 to 30 feet tall and cast deep shade.

Prune during the dormant season, typically in late winter, to remove dead or diseased branches and encourage new growth. Avoid over-pruning, as some fruit trees in desert climates may benefit from a bit more foliage for sun protection.

Timing Matters and Size Doesn’t

Fall or early Spring are the best times to plant trees — or almost any long-lived tree or shrub–in a desert garden. By planting now you will allow the new trees to acclimate and establish strong root systems before the scorching heat of summer arrives.

If you have any doubts about planting a backyard orchard because you think the space is too small, I hope you can visit the Tucson Mission Garden. You will see fruit trees planted densely and producing fruit, especially figs, abundantly. And then think of how good your own home-grown fruit will taste in a summertime fruit salad.

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Fixing that neglected side yard

It’s long. It’s narrow. And a home’s side yard is usually given little attention. Perhaps the original builder or an earlier owner spread a layer of rocky mulch on the soil and added a few stepping stones along the unused passageway from the front to the back of your home. But often it is not even considered part of the garden.

I have to confess that I ignored my current home’s side yard. A previous resident had, in fact, covered the 10 foot wide strip with reddish brown rock mulch. No stepping stones, however. There are pockets of grass where baby Mourning Doves huddle together and, in another corner, one rugged, volunteer Lantana plant survives. On one side of this passageway is a 6 ft. tall wood fence and on the other, the pale, sand-colored stucco wall for my living room. No windows — thank goodness.

Then, one day this last summer when it was once again 110 degrees fahrenheit outside here in Arizona I realized how much cooler that side of my home–the south side–would be if I planted something tall and shady there–a tree that was very drought resistant and wouldn’t die in relentless 100F+ heat.

Two drought tolerant trees for shade

My first thought was to install a Palo Verde tree in late October or November, when Fall planting season starts. I love this Arizona native’s brilliant yellow blossoms in April but once the flowers are gone, it would only provide a light screen effect with its leafless branches. Not much help countering the blasting sunlight in summer.

Then, I thought, what about another favorite of mine, the long-blooming Chitalpa (Chitalpa x tashkentsis)? Its branches would be ladened with pink flowers for months on end. And Chitalpa trees have leaves to cast more shade than the Palo Verde. Better yet, they grow fast and are so tough that in Las Vegas and Tucson they’re planted as street trees.

But I had to face reality: the passageway is only 10 feet wide and both the Palo Verde and the Chitalpa should be planted a minimum of 15 feet away from the side of a house.

So, a tall, skinny tree was called for–like an Italian Cypress (Cupressus sempervirens) which I know grows in Los Angeles and the Mojave desert. I haven’t seen many of them here in Sonoran desert gardens. A friend in Vegas planted a wall of them but looking at her garden now, maybe that is not the solution–especially when I check the price for 5 or 6 trees. I’ve been told that they suffer from red mites and if not watered deeply they will die.

Thanksgiving and cooler weather arrived and I stopped thinking about shady trees for my side yard. But in that doldrum week between Christmas and New Year, I began to consider it again.

Tough shrubs are a shady solution

Shrubs, I decided. Big, leafy, drought tolerant shrubs–maybe 5,6 or 7 feet tall–planted like a wall of shade next to the house. They will never grow tall enough to shade and cool the roof, but drought tolerant shrubs could block some of the blasting sunlight heating up the stucco. (Yes, Yes, I know I wrote about shrubs to cool concrete block walls last January. I’m now following my own advice.)

lantana hedge in Pasadena

Texas rangers (Leucophyllum frutescens) and upright Lantanas (Lantana camara) immediately came to mind. Both bloom often throughout the year, usually after some rain falls.

With some strategic trimming colorful Lantanas, like the ones in a hedge in Pasadena, can be encouraged to grow to 5 feet high. The Texas Rangers, however, I plan to leave untrimmed. I hate what commercial “gardeners” do to these beautiful, loose shrubs: whacking them into a lollipop shape with most of the lovely purple flowers cut off.

I’ll plant in February when we have had more rain and the soil is beginning to warm up. Now to figure out what to do to my back yard where a neighbor’s small tree died last year. It shaded both our yards and cut off the view from two homes behind us. Maybe that’s the right place for a Palo Verde or Chitalpa. I’ll let you know.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

Visit my author’s site to see the books I’ve published.

Should you get gardening advice from an A.I.?

You’ve probably already heard about ChatGPT, the new artificial intelligence program by OpenAI that is being called “scarily good.” Well, okay, I thought, maybe it is scarily good about techy stuff but how good is it with gardening advice? So I asked it this fairly basic question.

chlorosis shrub leaves

What causes plant leaves to turn yellow with green veins?

Here is what ChatGPT answered:

“Leaves on plants that turn yellow with green veins is a condition known as chlorosis. Chlorosis is caused by a lack of chlorophyll, which is the pigment that gives leaves their green color. The green veins on the leaves indicate that the plant is still producing some chlorophyll, but not enough to fully color the leaves.”

Okay — so far so good, I thought. And it continued…

“There are several causes of chlorosis, including:

  1. Nutrient deficiencies: A lack of iron, manganese, zinc, or other essential nutrients can cause chlorosis. This is often due to a lack of these nutrients in the soil, or a pH imbalance that makes it difficult for the plant to absorb them.
  2. Disease: Some plant diseases can cause chlorosis, such as leaf spot or rust.
  3. Pest infestations: Pests such as spider mites or aphids can suck the sap from the leaves, causing them to turn yellow.
  4. Environmental factors: Extreme heat, cold, or drought can stress plants and cause chlorosis.”

Item 2 is where ChatGPT begins to slip off the track. Leaf spot or rust do not look remotely like chlorosis; they are orangy yellow round spots on leaves not yellow leaves with green veins. Spider mites and aphids can damage plants but the effect is also spotty leaves–smaller spots–not leaves yellowing.

Then Chat GPT goes for the solution:

“To fix this issue, you need to find the root cause of the problem and take appropriate action. A soil test can help you determine the pH and nutrient levels in your soil and make recommendations for correcting any imbalances. You can also consult with a local nursery or botanical garden for help identifying and treating any diseases or pests that may be affecting your plants.”

That’s where ChatGPT ends.

My conclusion is that it offers basically good advice–as I did in an earlier post about yellowing leaves. But it falls short of the detailed information I wrote about, including short term, fast fixes to out-of-season yellowing leaves. ChatGPT clearly hedges its bet by suggesting that one should consult with a real local human being. (Or maybe a Master Gardener!)

Is ChatGPT trustworthy?

OpenAI, the company that developed this A.I. warns not to trust what ChatGPT says completely — that it sometimes just makes things up. This is a failing of other artificial intelligence programs, too. My guess is that it doesn’t want to appear ignorant — which, of course, opens the question about whether an artificial intelligence computer program can behave as if it is embarrassed by a lack of knowledge — but that is for another blog. Not this one.

I have another gardening question for ChatGPT — one that should be more challenging, but, unfortunately, the Open AI website is so busy that I haven’t been able to get on it again. I’ll report about it, if I can talk with it again.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

Where to get free or cheap trees in L.A., Phoenix, San Diego and…

The push for increased tree planting in cities around the world swells with each disruptive weather event. Whether it is reflected in nation-drowning floods in Pakistan or wildfires sweeping mountainsides bare in California, climate change has arrived. And ordinary people are saying: “We gotta do something.”

In response to clamor from citizens to “do something”, several U.S. Southwest city mayors have begun to set goals for the number of trees that should be planted in their communities. And they have enlisted the aid of organizations–usually utility companies–to help them by offering free or discounted small trees.

Before I go into how to get free trees locally, however, I want to answer a basic question.

Why plant trees?

Tree planting in cities has gone on for decades, mostly for aesthetic reasons. People like living and walking along tree-lined streets. There are now two other reasons to plant a tree at your home.

A street lined with Palo Verde trees that bloom brilliant yellow in April.
  1. As I wrote in the previous post, trees can become green canopies, natural umbrellas to cool hot city streets, sidewalks and other hardscape. It is a simple mechanical process: tree leaves blocking, reflecting or minimizing sunlight means cooler air and a cooler landscape underneath.
  2. There is also a chemical process that occurs when a new tree is planted. As they grow, trees absorb carbon dioxide, a gas that is a major contributor to climate change. Trees are carbon capturing plants that remove CO2 from the air and keep it stored in their leaves, trunk and branches. Less CO2 slows climate change. And the oxygen plants emit is the breath of life for people like you and me.

Trees planted for both these reasons make the world a pleasanter place for humans.

Ok. Now for those free trees

In Los Angeles, the Green New Deal identifies a goal of planting 90,000 trees. To reach that goal an organization called City Plants will deliver up to 7 free trees to your door. You have to plant them yourself but they provide instructions.

Crape myrtle

Don’t have space for another tree? They will also plant a street tree in front of your home or business, including obtaining the proper city permits.

City Plants also offers many “Adopt a tree” events for same day pick up of one fruit or shade tree. Check their website for details.

So who is picking up the tab for all this? The LA Dept. of Water and Power.

In Phoenix the goal is to plant 5,000 trees every year to increase the citywide tree canopy to 25%. It’s currently around 10%. Working in conjunction with Salt River Power and Trees Matter, Phoenix residents can take home 2 free desert native trees — mesquites, palos verdes, desert willows–after attending a Zoom meeting about planting and caring for trees. This program is underway for 2023.

San Diego is going in a different direction: homeowners receive a $35 rebate from San Diego Gas and Electric for each tree purchased up to a total of 5 annually. And–happy news for renters and condo owners–you don’t have to plant the tree in the ground. Put your 1 or 5 gallon starter tree in a big pot on your balcony or patio and you qualify for the rebate.

Chines pistache tree hot gardens

In Tucson, the goal is an ambitious Million Trees planted by 2030. Trees for Tucson, a part of the environmental organization, Tucson Clean and Beautiful, is selling locally grown trees for $30 each. You will have to plant the tree yourself.

A better tree deal comes from Tucson Electic Power. You can order up to 3 starter trees through their website for $5 each. They will send you an email about where and when to pick up your tree to take home and plant.

Like San Diego, Albuquerque uses a rebate program to help homeowners plant new trees. The ABQ Tree-Bate plan will pay a homeowner 25% of tree planting costs up to $100 as a rebate on the water bill. Better yet, the rebate can cover tree maintenance expenses and irrigation installation as well as the tree you plant from the city’s authorized list. Be sure to check the website before you rush out to buy a new tree.

And San Antonio, which really isn’t in a desert but I’m including it anyway, gives away free fruit trees at various special events around the city. (If you want more info about growing fruit trees in the desert go here.)

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Big goals but not involving homeowners

El Paso also has a goal of a Million Trees planted, but is working through a non-profit organization which solicits cash donations and does the planting itself. I couldn’t find anything about free or almost free trees for homeowners.

Another example of a non-profit soliticiting donations and doing the planting is Las Vegas where the mayor wants the city to plant more than 60,000 street trees by 2050 to provide shade and bring temperatures down in areas most impacted by the urban heat island effect. Nothing on the website about tree planting assistance for homeowners.

Now about those huge national and international tree planting organisations

I am suspicious of some of the organizations who will for a dollar or two or more promise to plant a tree on your behalf somewhere around the country or around the world. You may not be helping who you think you are. Some are commercial tree growers who plan to harvest the “tree you paid to have planted” in 15 to 30 years. “Your tree” may well become a roll of bathroom tissue! These people are not restoring permanent forests!

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

Visit my author’s site to see the books I’ve published.

Best 9 trees to combat climate change in the Southwest

Here in the hot, dry region of the U.S. Southwest tree planting has become more urgent as year after year the days get hotter and drier. The driving idea behind the tree planting efforts is to create a green canopy, a natural, cooling umbrella over cities.

In Las Vegas, the Mayor’s goal is to have 60,000 new trees planted by 2050.

In Tucson, the mayor is more ambitous: she wants to see a million new trees planted by 2030. El Paso, too, has set a million tree goal.

And In Los Angeles, one volunteer group, City Plants, installs 20,000 trees for free along the city streets every year. (More about free or almost-free trees in Western cities in my next post.)

If you want to do your part, but on a personal, residential scale, consider planting one or more of these trees–plus one shrub, the Chaste tree. Many are as wide as they are tall. They are all drought-tolerant and cast shade to cool your home and garden. I’ve added information about how tall the tree should grow, how fast it will grow and how long the tree should live. (Hint: All but one should outlive you!)

Trees that bloom in the Spring and Summer

Sweet Acacia (Vachellia farnesiana) is a species of thorny shrub or small tree. Brilliant yellow ball-like flowers, which are used in perfume industry. Will grow to 20 feet tall x 20 wide, moderate to fast grower. Lives 20 to 30 years.

Palo Verde (Parkinsonia florida) is a native to the Sonoran desert and is recognizable by the green color of its trunk and branches. Almost leafless most of the year, so it casts only a light shade. It bursts into brilliant yellow bloom in April. Grows 2 or 3 feet a year to 15 to 30 feet tall with an umbrella-like canopy. Lives 100+ years.

Desert Willow (Chilopsis linearis) can be grown as a small, messy tree or multi-trunk shrub 30 feet tall. Grows 2 to 3 feet a year. Lives from 40 to over 100 years, if planted no higher than an elevation of 5,000 feet. As a desert native it needs little care but, I repeat, it is a messy tree dropping those long, brown seed pods for you to clean up.

But read about the next tree, a tidier hybrid of the Desert Willow…

Chitalpa trees (Chitalpa tashkentensis) can grow as large, multi-stemmed shrub or a single-trunk tree. Unlike its cousin the Desert Willow, Chitalpa trees were created to be sterile and do not drop those long, pointy seed pods. For that reason the chitalpa is often planted as a street tree that blooms for months on end. Loves the endless sun shine and grows very fast to 30 feet tall. And is said to live up to 150 years.

Trees that turn color in Fall

Fan Tex Rio Grande ash has leaves that turn to a brilliant gold in fall, unlike it’s cousin, the ordinary Arizona Ash (Fraxinus velutina) that lacks the golden yellow fall color. Both ash varieties are adapted for a desert climate with low water usage. It is moderately fast-growing tree that will grow to a height of 30 to 50 ft and may survive 50 years with proper care.

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Chinese Pistache (Pistacia chinensis) is a pistachio hybrid that produces no nuts. In Fall the leaves on the male tree turn from green to gold to brilliant red then loses those leaves in winter. The female tree simply turns golden — not vibrant red. Grows 12 to 15 inches per year to a mature height of 25 to 40 feet tall and as wide. Should be planted in full sun; if planted in partial shade the result will be a lopsided tree.

Trees that need little maintenance

Mesquite (Prosopis velutina) commonly known as velvet mesquite, grows 12 to 24 inches per year to a mature height of 40 feet tall. Needs almost no care. It’s advisable not to plant it in a lawn that is regularly watered. Too much water or fertilizer weakens the roots of the mesquite which may then tip over during high winds. It will live for as long as 200 years. Equally durable in a desert garden are the Honey mesquite, the messy Screwbean mesquite and Chilean mesquite which has fewer thorns.

Chinese elm (Ulmus parvifolia). Capable of adding 12 to 36 inches of height per season, the drought-tolerant Chinese elm is a very rapidly growing tree with a weeping shape and deep shade underneath. Some lose their leaves in winter and others do not and it is not clear why this happens. This tree can grow to a height of 40 to 50 feet within 15 years. Lives 50 to 100 years.

A tree that produces fruit

Fig tree (Ficus carica) The common fig tree is a deciduous tree that can also be grown as a shrub or espaliered on a trellis. Produces fruit in 3 to 5 years. Grows 12 inches a year up to 30 feet tall and in its tree form ends up much wider than taller. Its large leaves cast very dark, cooling shade and a fig tree lives 50 to 200 years. For other fruit trees for the desert go here.

And my favorite shrub, the fragrant Chaste tree

Chaste (Vitex agnus-castus) is a hardy, fast-growing flowering shrub that produces bloom spikes of light purple, white, or blue flowers in mid-summer. If seeds and faded blooms are removed it will continue to flower. It has very fragrant leaves. Grows rapidly to a height of 20 feet — the size of a small tree–and lives for 15 to 20 years.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

Oh so yellow, gravel gardens and no mow rewilding

When April comes in Tucson and the temperature reaches to the high 80s F (30C) the Arizona native Palo Verde (Parkinsonia florida) trees burst into dazzling bloom. Street after street are lined with them and, were gas prices lower, I might be tempted to spend a hour or two every day driving around the city taking photos of them.

The Palo Verde is a good basis for a two-color garden–green + one other color–and yellow is a good color to pick because so many plants for hot, dry gardens bloom in yellow.

Plants for a yellow green garden

So here are a few plants to use in a green and yellow garden with almost no extra watering is required.

Two Palo Verde trees across the street from my home. Look closely and you’ll see others further on down the street. The only water this garden receives is rainfall of about 14 inches (35 cm) a year, most of that during the summer monsoon. In Spanish Palo Verde means green stick — the trunk and branches stay green year ’round. The leaves are tiny and, overall, the Palo Verde is not great as a shade tree –but awesome in April!

Going native with yellow flowering plants

yellow flowers on purple prickly pear cactus

Prickly pear cacti (Opuntia) in bloom. The variety on the right, the Santa Rita, has the bonus of bringing purple to your garden after the flowers fade. Another bonus with prickly pear: the fruit is edible and especially good as jam.

If you want a garden like an Arizona native, plant a Brittle Bush (Encelia farinosa) with its daisy-shaped yellow blooms. Actually, they grow well with little attention in both the Mojave and Sonoran deserts–that means in Las Vegas and Phoenix.

yellow lantana in bloom

If you don’t care about native v. non-native a golden yellow Lantana (Lantana montevidensis) fits right in a yellow-green garden theme. Whoever planted this South American native slipped in a couple of small purple Lantanas, but they are not as long-blooming or hardy was the golden yellow ones.

Of course, you can always add an annual like the Sunflower — Ukraine’s national flower–or Rudbeckia, a low-growing perennial with sunflower-shaped blooms. And your local plant nursery may have other suggestions.

Gravel gardens — a new trend?

While it may not be apparent in these photos, none of these gardens have lawn. The one near my home, has–as you can see in the photo–simple Arizona dirt underlies the garden. The Lantana was planted in fine pebbly mulch in a Southern California garden.

So I read with some amusement of the “new” trend toward gravel gardens in the U.K. and in the U.S. northeast. Basically, they are what we call desert gardens with rock mulch. In the northeast and U.K., however, the aesthetic choice seems to be grey gravel instead of golden or red sandstone colors. But planted lawns that have to be mowed, watered and intensively cared for — they’re out!

Rewilding roadsides may be dangerous

Another trend out of the U.K. is the rewilding of roadsides. It seems to have taken hold as more and more towns across England simply let the verge alongside roads become home to native plants and grasses instead of mowing them. Traditionally, May is the mowing month. But no longer.

In truth, many of these roadside gardens are not purely native: they receive a little boost with seeds of wildflowers scattered among the volunteer plants. While I like the rewilding idea, just letting plants and grasses grow along roadsides can create added wildfire danger here in the American West.

So while I can cheer the trend toward no lawn “gravel gardens”, I have problems supporting letting native grasses and plants grow uncontrolled along the Western roads and highways.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

Visit my author’s site to see the books I’ve published.

3 trees for Fall color in desert, but beware

With the limited color range in gardens in hot, dry desert climates–usually shades of brown and muted greens–having a tree outside your window that blazes with reds, yellows and oranges in Fall is a happy choice.

(I have a warning for you about leaves turning yellow at other times of year…but more about that later.)

First, let’s look at 2 big, beautiful, drought-tolerant trees and a small one that signal the change of seasons with their leaves.

These drought-tolerant Chinese Pistache (Pistacia chinensis) trees are still young. When mature, they are excellent shade trees at 40 feet tall and about 30 feet wide. Every Fall their leaves on the male trees turn from summer green to yellow to gold to blazing red–often with all those colors on the tree at one time as you can see in the photo at the top of this post. The female trees simply turn golden yellow. Strictly ornamental trees, they produce small non-edible red berries.

  • Rio Grande Variety of Fan Tex ash tree

The ‘Rio Grande’ cultivar of Fan-Tex ash (Fraxinus velutina) in this photo is about 14 years old. Not only is it a fast grower, it can be ideal for summer shade and winter warmth, after the leaves fall and the sun shines in. Once established, it is drought tolerant. While there are other ash trees that grow well in hot arid gardens — for example, the very fast growing ‘Modesto’ ash–only the ‘Rio Grande’ Fan-Tex ash leaves turn gorgeous gold in Fall. Click on photo to see it in summer.

And a colorful Fall and Spring tree for smaller gardens

If you do not have space for a very large tree, consider planting a crabapple (Malus) tree in your garden. They grow to about 15 feet wide and 15 feet tall. While needing regular watering, the crabapple flowers beautifully in Spring and the leaves turn a lovely orange/red in Fall. See second photo for spring blooms. If you should decide to buy one be sure to ask what the Springtime blooms look like. Some bloom white, some pink, some almost red and some are single blooms, others doubles. And the fruit is edible as a jam or pickle when cooked properly.

Beware of some yellow leaves

You may notice that the leaves on one of your shrubs are turning yellow — but the veins stay green–and it isn’t even Fall. This is an indication of plant chlorosis due to problems with soil conditions, specifically iron deficiency. There are commercial treatments you can use, like Kerex or other iron chelates and other spray-on treatments. They work short term. But improving the overall condition and chemical balance in the soil should be your next step after spraying for longer term results.

Listen to Mother Nature

Mother Nature plants in Fall and so should you. By planting at this time of year when the soil temperature has cooled off, the shrubs and trees have the opportunity to develop deep roots over winter and are, thus, stronger plants when they start to grow above-ground next Spring.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

Visit my author’s site to see the books I’ve published.

Winterproofing palms to survive climate change

You have probably already seen one: a tall palm tree wrapped in strips of burlap which the owners hope will protect the tree during winter cold. In truth, this burlap bandage going from the ground to where the fronds begin is unlikely to have any impact at all.

There is, however, a proven way to “weatherproof” and protect palm trees in areas where winter temperatures sometimes fall below freezing–places like Palm Springs, Tucson, Las Vegas and London. That’s right–palm trees are now being planted and thriving in London in the U.K., a city that is further north than Seattle.

Climate change is definitely having an impact on gardens worldwide and on which plants will thrive where. While we think of palms as warm climate trees, they are now being planted in areas where cold, freezing winters are normal. And future changes in weather conditions are becoming more unpredictable, except that it looks like extremes of hot and cold will become normal.

The Proven Way to Protect Palms

So here is how to look at the situation: The best way–the proven way–to winterproof palm trees, which thrive in warm to hot weather, is to start off right and plant one of the palms that are also hardy–one that has built-in DNA resistance to winter chill. And you may be surprised at how many palm trees fit this requirement.

Mediterranean Fan palm for identification purposes
This Mediterranean Fan Palm (Chamerops humilis) in Las Vegas is shrub-like – not tall and stately.

Let’s start with my London friend’s palm tree which she was told by her local garden center was a “New Zealand palm”. I recognized immediately that New Zealand had nothing to do with it. Her palm was and is a sturdy, hardy multi-trunk Mediterranean Fan Palm (Chamerops humilis).

Ideal for small gardens, this short shrub-like palm has survived brief cold spells down to zero F. (-18 C.) And “brief” is the important factor; their survival depends on daytime warming after a night of chill. It has been 14 years since she planted it in a sheltered corner and, growing slowly, it still survives, and recently has even bloomed and produced fruit.

The next on this list of chilly-weather survivors is the Date Palm (Phoenix dactylifera), a native of the Middle East. It’s the tree you probably think of when someone says “palm tree”. Tall with long pinnate (rather than fan-like) fronds, this 75 foot high giant is very hardy. It has been known to survive and regrow after experiencing temperatures down to 5 F. (-16C.) Dates are, obviously, edible and the difficult-to-find Bahri dates are the very best. Unlike the chewy Medjool dates you buy in a store, Bahri dates are soft, delicious and taste like caramel.

Next is the Date Palm’s cousin, the Canary Island Palm, (Phoenix canariensis). While a few of these palms have reached a mature height of over 130 feet, that is uncommon. But they still are among the tallest palms. It will withstand temperatures to 20 F. (-7 C.) at least for a short time.  After a cold snap the fronds will turn brown and may very slowly regrow.

Tall palm trees native to the West

More common in gardens here in the West are two fan palm trees. The California and Mexican Fan Palms, (Washingtonia filifera and W. robusta), natives of Southwestern U.S. and northern Mexico, are also rugged, surviving cold weather as low as 18 F. (-8 C.)

Trimming the “hula skirt” of dead fronds off these trees may make them look a bit more tidy but that “skirt” offers the palms some protection, some insulation from severe weather. The downside of not removing dead fronds is that Mother Nature may do it for you during our fierce Spring and Fall windstorms. And falling palm fronds are very dangerous. The thorns on these fan fronds are also hazardous.

Like the date palms, the Washingtonias can reach heights of 60 to 100 feet, making them not particularly suitable for residential gardens although we see them planted around homes everywhere. After a few years’ growth they are more like architectural columns in a yard than trees.

Shorter palms for home gardens

A native of Mexico’s rocky Guadalupe Island, the Guadalupe Fan Palm (Brajea edulis) is a distinctive palm with a smooth grayish-brown trunk and silvery fronds. It grows about a foot a year to a mature height of only 25 feet tall, ideal for a residential garden. It flowers in summer from long drooping stems and the blooms are fragrant. Because it is a native to a small island with variable weather conditions, it tolerates heat, wind and drought, and it is one of the hardier palms, to 18 degrees F. (-7.7 C)

Pindo Palm (Butia capitata) , a native of dry South American savannahs, is another short palm, growing only to 20 feet. In Florida where it is popular in home gardens, it is known as the Jelly palm because people make jelly with its fruit. It tolerates temps as low as 5°F (-15 C) In this photo a very young Pindo palm was planted at the same time as the Washingtonia behind it. They have very different growth rates.

Originally found in high altitudes in China, Japan, Myanmar and India, the Windmill Palm (Trachycarpus fortunei) is a semi-dwarf palm with windmill-shaped fronds. Slow-growing to 15 feet tall, this tree loves our summer heat but will withstand winter temperatures of -10F (-23C).

My favorite fails the chill test

My favorite is the graceful Queen Palm (Syagrus romanzoffiana) a native of South America commonly planted in Southern California. It does not do well at all in cold weather. While I’ve seen it planted in hot dry Palm Springs, but with the weather uncertainty stemming from climate change, it may not survive there at all, except in a local micro-climate. Nearer the California coast, it grows beautifully and is ideal for home gardens.

And finally…

If a freeze comes and your palm tree ends up with browned fronds, do NOT remove it right away. Give it a few weeks or even a month or two of Springtime weather and it may very well produce green fronds again. And if you have to replace it in the end, choose one of the palms on this list.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting

4 desert trees good for the soil and 4 toxic ones

Recently Tucson’s Mayor Romero announced a tree planting goal for the City: one million new trees planted in the next ten years to help combat climate change. (That works out to 274 trees a day!) Homeowners are encouraged to plant one or more trees around their homes. But the number of tree choices for hot dry gardens runs into the dozens. So how to choose?

Trees related to peas?

In the hot dry gardens of the Mojave and Sonoran deserts homeowners should consider the benefits of planting these 4 trees that belong to the pea family. Why pea family trees? Because they take in abundant nitrogen (NH2) from the air and convert it to ammonium nitrogen (NH4) which gets added to the soil via bacteria-filled nodules on the tree roots.

So, not only do these trees do what all good trees do–provide shade and remove carbon dioxide from the air–they also help other plants beneath and nearby to thrive by providing nitrogen to the soil for nutrition.

You see this everywhere in untouched, natural areas, like this photo from the Saguaro National park: cacti and other plants growing right under and up through trees.

Food for the soil and plants nearby

First on the Good-for-the-Soil List: Mesquite (Prosopis). Among the most common varieties of Mesquite are Argentine mesquite (P. alba), Chilean mesquite (P. chilensis), honey mesquite (P. glandulosa), the screwbean mesquite (P. pubescens ) and velvet mesquite (P. velutina). The honey and velvet mesquites produce edible seeds pods that are commonly ground up into a flour for cooking. The screwbean is quite a messy tree. In size, mesquites range from 8 to 10 foot tall shrubs to 40 foot tall trees.

Mesquite tree prosopis
Mesquite alba in Las Vegas

They are super-easy to grow. On my short walk this morning I noticed dozens of young volunteer mesquite trees sprouting along neglected areas next to the street. If they are left alone, within a few years they will become trees with no help from anyone.

Trivia: in Australia and Ethiopia mesquites were introduced a few decades ago and loved the weather and land so much that they are now regarded as invasive pest trees because they are aggressively taking over grazing lands.

palo verde tree at Sunnyland garden
“Palo Verde Tree, Sunnylands, CA 2-22-14” by inkknife_2000 (11.5 million views) is licensed under CC BY-SA 2.0

Second on the Good-for-the-Soil list: Palo Verde trees (Parkinsonia florida), the Official Arizona State Tree. In Spanish the name means “green stick” with good reason. It is immediately recognizable by the green color of its trunk and nearly leafless branches. In Spring it bursts into bloom with brilliant yellow flowers and small leaves emerge, only to fade away quickly. While it does not cast much shade, it too helps other plants thrive by fixing nitrogen in the earth. The Foothill Palo Verde, which has a more yellow tinge to the trunk, reaches 20 feet in height. The blue Palo Verde can grow to 40 feet tall.

Acacia in bloom at Los Angeles Arboretum

Third, we have the Acacia tree (Acacia), which some claim should be knick-named the “Allergy Tree”. These fast growing Southwest natives love the heat and bloom with yellow powder-puff flowers in the spring that leave a pretty carpet of yellow pollen and spent blooms beneath them. Some also bloom again in the Fall. The larger varieties will reach 40 feet in heights and provide excellent shade, but there is one smaller variety suitable for courtyards.

Food for the soil and people, too
“Carob tree” by tree-species is licensed under CC BY 2.0

Fourth, and a little harder to find, is the Carob tree (Ceratonia siliqua). Not only does this Mediterranean native tree add nitrogen in the soil, it has pods that, when ripe, can be ground up and used as a substitute for chocolate. Be sure to read instructions online if you plan to do this.

Growing to a height of 50 feet carob trees cast dark, cooling shade. Unlike the previous three on this list, it needs some water year ’round. It is, however, on the suggested tree list in Tucson. For whatever it is worth, it is one of my favorite trees and Carob ice cream was very popular among the hipsters in San Francisco in the 1960s.

4 Toxic beauties

But not all trees in the pea family are good. There are some toxic trees in the pea family which are quite beautiful and are planted in hot dry gardens throughout the Southwest–and probably shouldn’t be. While they can fix nitrogen in the soil they are best NOT planted in a family garden because of the dangers they can pose.

The Golden Medallion tree
Golden Medallion tree in Tucson

The striking Golden Chain tree (Laburnum × watereri) is uncommon, temperamental, and all parts are poisonous. The brilliant yellow flowers hang down like long chains of gold, which is where the name comes from.

The Golden Medallion tree (Cassia leptophylla) is similar in appearance to the Golden Chain tree. Its pods are poisonous.

The umbrella-shaped Mimosa tree (Albizia julibrissin) with its pretty pink-white flowers has poisonous seed pods and a reputation for being invasive.

The small Texas Mountain Laurel (Dermatophyllum secundiflorum) is a shrub-like tree with lovely purple blooms that look like wisteria or lilacs. Its brilliant red seed pods are deadly poisonous.

For more information about trees suitable for hot dry gardens, go to our Leafy Trees for Shade page.

Our 8 most popular newsletters

  1. Where to get free or cheap trees for your garden
  2. Six distinctively different landscapes to replace a lawn
  3. Cover up that naked wall
  4. Five fragrant plants for your garden
  5. Nine trees to combat climate change
  6. Four desert trees good for soil, 4 toxic ones
  7. Plants that bloom even in mid-summer scorching heat
  8. Follow 90F degree rule for planting