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Saving a garden in relentless heat

As of today Tucson has suffered under daily high temperatures over 105F (44.5C) for 39 straight days. And the TV weather lady tells us these conditions will keep on going. No monsoon rain relief in sight in this part of the Sonoran desert. A friend in Las Vegas tells me it is as bad up there in the Mojave desert.

While this persistent heat is awful for humans, we can take shelter in air conditioning. Plants in the garden, however, cannot. So, what to do to help your plants survive this–or any other–extended period of heat?

The first thing that may come to mind is to increase watering the garden. Sadly, deep watering plants may or may not help. With day-after-day of temperatures of 90-100F+, some plants, particularly non-desert plants, cannot absorb water faster than it is evaporating through the plant’s leaves. Death by dehydration results.

Here, however, are 3 ways to help your plants survive until Fall.

Shade Cloth is a quick remedy

tucson tree under shade cloth
Photo Copyright by Tiffany Weerts 2020. An improvised shade cover in Tucson during a long hot spell.

Shade cloth is a fast solution for plants that appear to be suffering from heat exhaustion. You can buy it today, hang it up over vulnerable plants or borders in your garden and the protection starts immediately even if you have to just tack it up in a temporary make-shift way. Shade cloth comes in variety of weights and with UV protection.

Double pot to cool roots

For the plants that are in pots the heat and afternoon sunlight can be especially brutal. Placing pots where they will be in shade for most of the day is a recommended, but that may not be enough. Again, the problem is death by dehydration–water evaporating too rapidly through the leaves and from the potting soil. Compounding that problem is that terra cotta and metal pots heat up and can “cook” the roots.

Keeping potted plants in shade can help them survive, but double-potting increases the likelihood of the plants surviving summer heat.

However, one way to help your potted plants survive on the patio in summer is to set each pot in a second, larger container. Then put an insulating layer of dried moss or coarse organic mulch between the two pots. This will keep the inner pot cooler and protect plant roots from sizzling heat. You may want to try to keep the insulating layer damp–but beware of soaking it because the water could pool inside the outer pot and soak up into the inner one. You could end up drowning the plants from the bottom.

Consider using one of the newer plastic pots as your outer pot. They are far more attractive than they used to be and conduct far less heat than terra cotta pots. The insulation may also be helpful in winter, if you live in an area where it freezes in winter.

Controversial polymers

Polymers, those water-retaining gel crystals, are frequently used in flower pots to help cut down on watering and retain water in the soil for the plants’ use. This isn’t an instant solution, but polymers can help over a longer term–like all those hot days ahead of us here in the Sonoran and Mojave deserts.

Recently, however, we heard a gardener advocate using water-retaining polymers in flower beds and in the soil around trees.  It sounded like a good idea — particularly in a climate where water evaporates out of the soil so rapidly.

But a little online research revealed a preliminary study which indicates that polymers may break down in our native soils into chemical components which may not be all that good for plants and people. So while polymers may be a great solution for flowering ornamental plants in pots, stick with adding organic amendments, such as crushed pecan hulls or finely ground wood chips, to your garden’s natural soil to increase its water-retaining ability. Moreover, organic amendments add nutrients to the soil, which polymers don’t. If you would like to review the research yourself, to go Google and search for: “Polymers Gardening.”

And if the heat kills most of your plants–which is happening in many gardens here in Tucson now–you can replant in late September or early October.

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

What NOT to plant for fire season

I have always loved what I call the “Tucson Gardening Style“. No broad swathes of grassy lawn browning in the sunshine. No water-guzzling attempts at English flower garden borders limp in the heat. Just native plants left where they were growing before any house was built: prickly pear cacti squeezed side-by-side with creosote bushes and saguaros and agaves and chollas and mesquites. And most of the time these Sonoran desert natives grow right up to the side of the house.

But on June 5th, after the Bighorn wildfire burst into life north of Tucson, this native plant gardening style suddenly seemed less charming and more threatening.

At first the Bighorn fire was just billowing smoke high up in the Santa Catalina Mountains. By June 9 when I drove around northern Tucson to to take photos for another blog, I began to realize an inferno would result if this fire reached down into the upscale Catalina Foothills neighborhood which had only hours before been designated as a threatened evacuation zone.

As I took a few pictures I also realized that in California, where I used to live, the “Tucson Gardening Style” would bring the fire service knocking at the door armed with chain saws and big fines. The law in California is that there must be a 100 foot cleared open space around a home and it is aggressively enforced.

There is, however, such a live-and-let-live “Nobody’s going to tell me what to do” outlook by many Arizonans that it is unlikely that type of regulation would ever be passed here.

Okay, while I live in Arizona now I’m going to ignore local attitudes regarding plants because wildfires happen here and throughout the Western United States. Here are some recommendations about garden plantings to help prevent your home turning into an pile of burnt rubble from an urban or wild fire.

First, clear plants away from the sides of your home and other buildings. Don’t let any shrubs or trees touch or almost touch a building. If the plants catch fire — even if ignited by sparks from a neighbor’s BBQ instead of a wildfire–your home could burst into flames before you even notice it.

While many trees suitable for hot dry climates have oily leaves, the Australian-native Eucalyptus trees are among the worst. Sure, they smell so good, but they are 50 foot high torches just waiting for a little spark to light them. As much as they seem to be great trees for hot dry climates (fast growth, low water usage, lovely dappled shade), they are not. As witness: the massive fires racing through the Eucalyptus forests of Australia in recent years.

I have also seen palm trees burning as 50 foot high torches in Los Angeles during an urban fire, but while embers fell from the palms, they did not seems as potentially dangerous as a flaming eucalyptus with its branches whipping in the wind casting sparks all over the area.

For very a different reason don’t plant a Cottonwood, a major water-sucking plant. Again, it is a fast grower, but will guzzle every drop of water in the ground around it and deprive other plants of water, leaving them tinder-dry. Cottonwood roots will also invade your plumbing and septic systems.

One grass is on the Do Not Plant list:

Buffelgrass (Cenchrus ciliaris L., or Pennisetum ciliare L.) is often called white fountain grass. An African native, it grows and blooms quickly, then dies back to leave dry, quick-burning fields waiting for a lightning strike to start burning. This grass, a threat to native plants including Arizona’s famous Saguaro cactus, has been mentioned as a key factor in the origin of the Bighorn fire. You can view a new webinar on the topic of buffelgrass damage to the Saguaro National Park .

Red Fountain grass does not spread wildly like White Fountain Grass. And it looks lovely when the wind blows.

Instead of Buffelgrass, consider Red fountain grass (Cordyline) which is less invasive and stays where it is planted. The much larger South American-native Pampas grass (Cortaderia selloana) will also stay where it is planted in a desert climate, but not if there is a pond or stream nearby. In that case it becomes invasive forcing out native plants.

Now onto something more positive. While the evidence is anecdotal, a few homeowners have sworn that their huge water-logged agaves saved their homes during a wildfire. I’ve seen the photos and the agaves encircling the homes look as if they have melted, but the houses were spared. It’s important to note that there was a cleared space between the house and the agaves and beyond the agaves, too.

As for planting any trees or agaves, wait until fall. It is too hot now and there is a great risk that anything you plant will die of heat at this time of year no matter how much you water it. Don’t let the landscape guy tell you otherwise!

The Bighorn fire is still burning on June 19th, but because of a wind shift, it is moving northeast, away from Tucson proper. A photo of it taken yesterday is at the top of this post. According to reports over 3,000 Saguaros have already been destroyed, but–happy news–most of the wild animals in the fire path, including baby mountain goats, have escaped. And there has been no loss of homes or human life so far.

Here is what happens to an SUV when the Forest Service makes a Phos-Chek drop. It’s that red stuff fixed wing airplanes drop on the edges of fires.

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

Texas Rangers are the earth’s “Thank You” to the monsoon

In recent weeks TV weathercasters in the desert Southwest have been laughingly referring to the “non-soon” as the annual summer rains got held up in West Texas. And, to make it worse, even fewer clouds came out of the Sea of Cortez. No rainstorms from either direction. Finally in late July one storm dropped enough rain to begin bringing Texas Rangers (Leucophyllum fructescens) into bloom.

Texas Ranger Leucophyllum frutescens in bloom

Since then even record setting temperatures have not slowed the rush to flowering by these heat loving shrubs, native to the Chihuahua desert. They are a visual joy in blue, purple, lavender, and white!

Texas Ranger untrimmed
Thanks to Starbucks in Marana AZ this Texas Ranger has been left untrimmed, although perhaps with too much shade on the plant. It prefers full sun.

Better yet, as SW natives the Texas Ranger thrives in very alkaline soil of .8 to .9 pH. While these 8 foot to 10 foot tall shrubs bloom in concert with the monsoon, they prefer fast draining soil to keep their roots almost dry so be sure to add plenty of organic material when you plant a Texas Ranger. And only irrigate them–lightly, if at all–during the summer months. Stop watering at the end of the monsoon in late September. And as for fertilizer? None needed at all. Fertilizer makes them spindly and weak.

NOW FOR MY RANT: Do not trim Texas Rangers into lollipops! Commercial groundskeepers seem to be the worst offenders of this practice, as you can see in the photo below. Texas Rangers have a beautiful loose shape and should be allowed to keep it. If you feel you absolutely have to cut back a plant, do it in March–one time during the year, only once! Or maybe plant a dwarf “compacta” variety instead. END OF RANT.

improperly trimmed Texas Rangers shrubs
These 4 Texas Rangers in a parking lot have been severely trimmed. Whoever developed the horticulture plan for this commercial area should have chosen the Leucophyllum frutescen ‘compacta’, the low growing variety of the plant.

Amazon Burning- what you can do

The new President of Brazil ran on a platform of developing the Amazon. What we are all seeing now is that landowners, particularly cattle ranchers, took that to give them a greenlight to start burning their way deeper into the life-giving jungle after he took office.

Now we can all be outraged as Presidents Macron and Trudeau have been on Twitter or we can actually do something about it in the real world. Countries like Pakistan, India, China, Senegal, Nigeria and even tiny Nepal have already embarked on programs to plant millions of trees.

While we can have no hope of getting support from the current administration in Washington D.C. for a massive tree planting effort in the U.S. I am confident that local groups, like the Tree People in Los Angeles or the National Forest Foundation, will continue and expand their Plant-A-Tree programs in cities, towns and forests across the country.

Crepe myrtless in bloom

If no organization near you is doing it at the very least plan to add a tree to your garden this fall when planting season begins. If every person in the U.S. planted just one tree we would have 329 million new trees which would help offset the damage being done right now in the Amazon.

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

Be a superhero! Plant flowers and save the world’s food supply

Okay.  Maybe that headline is a bit extreme…but it is not that far off.  Here’s why.

As we all have heard, bees seem to be vanishing all over the planet. And without them to pollinate edible plants–whether tomatoes in Pasadena or romaine in Yuma or pecans in the San Pedro river valley–we humans may be in trouble and face food shortages.

And it turns out that flowers can be part of the solution.

Red and Yellow cherry tomatoes Hot Gardens

At a recent gardening event in Los Angeles a speaker recommended planting annual flowers between tomato plants to encourage more bees to pollinate the tomatoes while they are seeking nectar from the larger, flashier annual flowers. It helps keep the bees well fed and the bee colony thriving. Tomato plants will produce more abundantly, too.

“Wait a minute”, you say. “There are no commercial growers near me and I’m not growing vegetables in my backyard. Why should I encourage bees?”

The answer is that you can become part of a larger effort to sustain genetic diversity all over the planet.  That’s where the Gardener-Superhero role comes in.

As I look at many desert style gardens filled with agaves and other rarely flowering plants I realized that our new water-wise gardens are creating starvation conditions for our friends the bees. Not enough variety, not enough flowers blooming for not a long enough time.  Worse yet, in many desert areas, the native plants that could provide nectar to bees are being removed to make way for houses and roads.

It is, however, not necessary to plant water-guzzling plants to have bee-friendly flowers in a hot, dry garden.  Here are some that will thrive and  produce flowers over a long period without running up your water bill.

Lantana ground cover mixed colors
The low-growing Lantana (Lantana montevidensis) comes in many colors these days.

Low-growing Lantana (Lantana montevidensis)  is one of the best and most readily available flowering plants for hot, dry gardens. Bees and butterflies love it! It blooms for as long as 9 or 10 months out of the year and because it is a perennial, rather than an annual, you will not have to replace it every year. Be aware that the purple and white varieties bloom for a much shorter time than the gold, yellow or varigated Lantanas. Upkeep is easy: in mid-winter cut the low-growing branches back to a foot or so in length.

Instead of the low-growing lantana, however, consider planting Lantana camera.  It grows to 6 feet tall and makes a very colorful, bee-friendly hedge. A light mid-winter trimming is all the maintenance needed.

Next, Rosemary (Rosemarinus officinalis) attracts bees like a magnet and can provide a delicious herb for your table. Plant several about 2 feet apart to create a rosemary hedge or simply put one plant outside near your back door to clip and use the aromatic leaves in bread or for baking chicken.

Lavender (Lavendula) is another tasty and aromatic herb that bees love as much as humans do.  I prefer French lavender to the English or Spanish varieties, but I have to confess that I have not had much success keeping lavender plants alive from year to year. I simply replant annually.

And finally: annual sunflowers.  If you plant the seeds over a period of a couple of weeks, you will have a longer blooming period for the bees to harvest the nectar. Then later, birds will come to harvest the seeds. You can harvest them, too, and then toast the seeds in your oven for a tasty snack.

So get out your garden gloves and think of them as the red superhero cape for gardeners.

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

The dirty truth about yellowing leaves when Fall hasn’t even arrived

chlorosis shrub leaves

It is a subtle change but one day you notice that the leaves on one of your shrubs (or maybe a tree) are turning yellowish and as far as you know yellow leaves are not natural to this plant–even in Fall. You look closer and see that the veins in the leaves are still green as you can see in this photo.

Well, what you are looking at is chlorosis, a kind of iron-deficiency in plants that inhibits the development of chlorophyll, the stuff that makes green plants green and keeps them alive and growing.  It is most common in plants grown in alkaline soils with high pH.

The problem begins in the dirt, the soil in your garden.  Even in hot dry desert-like gardens there is ample iron in the soil, but unfortunately plants can’t access it. The technical causes for the iron/soil problems read like a chemistry textbook so I will skip it, but advise you to take steps to reverse the condition before it gets worse. After all, you don’t want to lose an expensive plant or tree, especially to a plant problem that is curable.

What you need to do at this time of year is apply a foliar spray of iron chelate (pronounced “key-late”) to the leaves of your plant. It is available online and probably at a local big box gardening or hardware store for less than $15. It may take repeated applications of the spray to green up your shrub again.

But even a foliar spray is a temporary solution, effective for two or three months.

The next steps are to

  • Test the pH of the soil around the plant with chlorosis using an inexpensive pH testing kit which you can easily find online.  You may want to test other parts of your garden too.  (In fact, you may want to check the pH every year!)
  • Add chelated-iron fertilizer to the soil around the plant or tree IN SPRINGTIME (not Fall).  This is a longer term solution than the foliar leaf spray.
  • Dig in extra amounts of organic materials in the Fall and the Spring to balance the soil in your plant beds to a neutral 7 pH.  If you can get it to 6.5, all the better. Plants love 6.5 pH!  Keeping a high level of organic materials in and around the plants is a long term solution to chlorosis.
Rio Grande Fax Tex Ash autumn

BTW, if you have a Fan Tex Ash tree the leaves on it will naturally turn yellow in Fall. It is one of the very few trees for hot dry gardens that has lovely Fall color. (Of course, there are the aspen trees that grow in the mountains around the deserts and also become golden in Fall.)

CLIMATE CHANGE UPDATE

In an abrupt about-face the Australians tossed out their Prime Minister who announced last week that keeping fuel prices low was more important than meeting Paris Accord climate change limits. Among the first things the new PM stated was that climate change came first–particularly in light of the severe drought that is impacting ranchers in New South Wales, outside of Sydney.

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