Category: U.S. Southwest

Mesquites and flowering trees to plant in your hot, dry garden this Fall

Mesquites seem to have become the Street Tree of choice in some cities in the arid Southwest.  Cities can line the streets with allées of Honey mesquite (Prosopis glandulosa) or Velvet Mesquite (Prosopis velutina) knowing full well that maintenance is not going to break the city budget.  As natives these trees thrive in harsh, dry climates with almost zero upkeep. And Fall is the best time to plant them.

Mesquite prosopis
The Mesquite is for all practical purposes a plant-it-and-forget-it tree, but the shade it provides allows other plants thrive.

When you plant keep in mind that  irrigating and fertilizing a mesquite is a mistake and planting one in a lawn that is regularly watered can be a disaster: the roots will be shallow, the tree will become top-heavy and topple over in the Spring and Fall windstorms.

A third native mesquite, the Screwbean (Prosopis pubescens) is more of a tall, thorny shrub and is best planted in an out of the way place.  One Screwbean mesquite I saw not long ago was tucked back in a no-irrigation zone of a large Las Vegas garden where it and a nearby Desert Willow (Chilopsis linearis) were surrounded by a protective circle of agaves.  A good choice of companion plants!

Desert Willow and agaves
A Desert Willow and a Screwbean Mesquite make good companions to these agaves.

In addition to these three, other mesquites from Chile and Argentina have been introduced into the Southwest and have cross-bred like crazy with the locals. And thorns have turned up unexpectedly on supposedly thornless mesquites.

The problem with these fast growing, very drought tolerant trees is that they don’t give us colorful blooms in our gardens.  Yes, yes — I know they “bloom”–after all, that’s where Trader Joe’s Mesquite Honey comes from–but the blooms are very subtle.  Bees may notice them, but the average person driving along the street won’t.

So here are a few recommendations of trees to plant this fall that will produce colorful blooms in summer.

The first two I have already written about but are worth mentioning again.

chitalpa tree
This Chitalpa tree was planted as a “whip” about 4 years prior to this photograph being taken.

The  Chitalpa tree (Chitalpa x tashkentensis) was especially developed for low water usage gardens — by Russian scientists, no less.  The “tashkent” in its name is the capitol city of Uzbekistan formerly part of the old Soviet Union  where the scientists worked. Why those scientists spent time developing a ornamental garden tree–rather than a practical fruit or nut tree–I will never figure out.  But I thank them.

Anyway…it is definitely a favorite because it blooms in pink, or white, or lavender  for months on end in summer. It needs some watering, grows 2 or 3 feet a year and reaches a height of 25 feet tall. Bonus:  hummingbirds love it.

Crape myrtle
In addition to pink and hot pink, one Crepe Myrtle has showy white flowers in summer.

The Crepe Myrtle (Lagerstroemia indica) can be a glorious blast of color in the summer, although be aware that it does need watering to do its best. A row of them behind our local library did not get irrigated this summer and failed to put on the usual bright show of flowers.

By nature the Crepe Myrtle is a shrub although some plant growers train them to be a small tree or standard.  It tolerates neutral to slightly alkaline soil so be sure to add mulch around it at least once a year.

The Gold Medallion tree (Cassia leptophylla) is a Brazilian native that is now being planted in drought tolerant landscapes in the Southwest after being introduced to the U.S. by the Los Angeles Arboretum in 1958.

Brazilian gold medallion tree
This young Gold Medallion tree will easily grow to twice this height.

It flowers with huge basketball size clusters of yellow flowers at the ends of branches and the hotter the weather the more the blooms.

Happily, it also tolerates mildly cold weather down to 25° F for a short time. The City of San Francisco, of all places, is using it as a street tree and it is chilly there, for sure!  The Gold Medallion tree needs soil that drains well and do not over-irrigate. It’s seeds are poisonous.

Now about Oleander…Yes, it blooms in summer, is drought tolerant, and grows fast. And every bit of the plant is poisonous–leaves, branches, flowers–everything. Seriously, it can kill people.

CLIMATE CHANGE
In the last few days many of us in the Southwest were blessed with rain. It soaked into the earth in some places and in other areas created flash floods. This rainfall came from the remains of Hurricane Sergio.  As the Pacific ocean warms up along the California coast, we can expect more after-effects from hurricanes and, before long, full-fledged hurricanes actually blowing into Southern California and eastward. This year the water temperature off So. Cal. was 78° F. That’s 10° above the historic normal. The weather folks tell us hurricanes need 80° F water temperature for energy–and that’s only 2 degrees away.  I look at the photos of the destruction caused by Hurricane Michael in Florida and hope we do not have to experience that here.

Our 8 most popular newsletters

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

All hail Queen Agave new ruler of the front lawn replacement

Front yards don’t look the way they used to.  For generations, the American standard  from coast to coast has been green grass as a carpet in the front of the house.  Mowed once a week. It was all very orderly and not many decisions were involved.  The homeowner’s “garden personality” was expressed in the choice of shrubs or flowers chosen to line the edges of that green carpet like a fringe.  Lawn replacement didn’t even enter people’s minds.

(NOTE: It is still too hot to plant in most of the Southwest, so I am writing about Lawn Replacement again!  Wait until the temperature drops below 90 degree F before beginning Fall planting.)

Now as homeowners in the West under the pressures of drought and climate change rush to remove these conventional front lawns no clear single standard for replacement exists.  What many homeowners know is that the grass in front of their house is “bad” and needs to go.  The Water Department said so.  And even offered to pay part of the replacement costs.

Homeowners are facing new lawn decisions
gold lantana
Gold Lantana is one tough ground cover that thrives with very little water and a lot of neglect. Too much fertilizer will make it bloom less. It comes in a variety of colors ranging from white to blue to pink to orange. The white and blue do NOT do well as lawn replacement.

“Agaves? Aloes? Aeoniums? Or maybe a single color field of gold Lantana?  Yeah. That sounds good.  Just one type of plant and one color. Oh–but will that be too much gold? Would pink Lantana be better?  Or maybe native plants?  Or maybe… [pause] Or maybe I’ll just hire someone to do it for me.”

While homeowners may be overwhelmed by these decisions, many of the landscapers installing these new front yards are not.  Agaves seem to be becoming the basic plant around which low water usage gardens are being created.

Now I have nothing against agaves.  Without them we wouldn’t have Margaritas.  And long-nosed bats would simply be another vanishing species if agaves disappeared.

Moreover, these plants are practically indestructible with a lifespan of several decades.  (Yes, I know they are called “century plants”, but they really do not live for a 100 years.) Professional landscapers love plants that they can stick in the ground and then count on to remain alive long after they have left the scene. They do not want to hear complaints about plants dying on previous jobsites.

So agaves it is.

But these plants need visual softening, some other plants to add visual variety.  Even the plant-and-go landscapers recognize that but rarely do ornamental grasses become their first choice as “other plants”.

The lawn by this row of Pampas grass has since been removed. Behind it is a dull gray block wall. In winter cut the Pampas grass back to 18 inches in height.

I wish they would.  From a 15 foot tall Pampas Grass (Cortaderia selloana) to line an unpainted block wall to 6 inch tall Mondo grass or Lilyturf (Liriope muscari) to cover a gentle slope in green, ornamental grasses are interesting and beautiful additions to a drought-tolerant garden.

Agave, deer grass, blue fescue, rocks Hot Gardens

A Large Agave surrounded by grass and rocks
This mix of Blue Fescue (Festuca), Deer Grass (Mulhenbergia rigens) and Agaves along a simulated creek bed filled with rocks is a classic image of lawn replacement using drought tolerant grasses.  It takes an artistic hand to site these plants in a way that looks good.  It also takes money.  Creating artificial streams can be very expensive.

Grasses to line a garden path
Pennisetum setaceum 'Rubrum' Hot Gardens

Far less expensive is Red Fountain grass (Pennisetum setaceum ‘Rubrum’) planted along a sidewalk.  It becomes a colorful addition to a drought-tolerant garden. It is especially attractive in  Autumn when it blooms and dances in the wind. The nearby Agave is good for structure, but not for gracefulness.

Next are a pair of photos showing before and after Mexican Feather grass (Nassella tenuissima) was added to a garden of Agaves and Aeoniums.  Sadly, the “Before” photo with chopped off Feather grass in a distant corner was actually taken in September of 2018.  The “After” was taken in 2016.  Why the homeowner decided to whack off the Feather Grass before he put the house up for sale is beyond me.

Before: A garden of Agave and Aeoniums
Agaves and aeonium garden Hot Gardens
With no Mexican Feather grass this front garden simply becomes a mass of plants with thick leaves in basically the same color.
After: Adding Mexican Feather Grass to the Agave gardenAgaves, Senecios, Mexican feather grass Hot Gardens

For a hilarious take on Agaves, read this very funny article by Frank Smith in The Awl.

Our 8 most popular newsletters

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

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The Waterless Garden Fountain: Part 2

Fountain surrounded by flowers Hot Gardens
Water once trickled out of the top of this solar-powered fountain. As water restrictions increased the fountain was turned off. Here flowers cascade around it.  To see how it looks in 2018 go here.

In Mexico, just south of Tijuana, the highways are lined with semi-improvised shops – at least they were the last time I was there several years ago.  In almost every one of these shops cast concrete garden fountains were for sale. Some were two-level; some three-level; all had elaborate decorations. But I suspect that the never-ending drought conditions across California and the U.S. Southwest have forced those garden fountain fabricators to turn to making other garden ornaments.  Benches, perhaps, or concrete angels.

Drought conditions also have forced many people who purchased a fountain in Mexico or their neighborhood garden shop to turn them off as urban water restrictions increase. So it is time to put those fountains and the shallow pools that surround them to another use as raised flower beds. Cascading flowers, obviously, replace cascading water.

The photo at the top of this page gives you one example. The solar-powered fountain has been turned off and colorful and sturdy coneflowers, daisies, California poppies, and black-eyed Susans (Echinacea) spill over the sides of the raised bed around it. This design works best when the fountain is relatively plain.

(In my last post you can see how this fountain area has changed again as the drought has continued. In the current version of the fountain at the entrance to Arlington Garden in Pasadena, the colorful flowering plants have been replaced with low water usage, mounding plants that do not bloom abundantly. The fountain still  isn’t flowing but an inch of water has been added to the basin for use by birds and small animals.)

3 level fountain succulents Hot Gardens
This fountain never has had water bubbling over the sides. It has always been used as a planter for succulents, which need regular hand watering.

Arlington Garden also has a good example of how to convert a three-level fountain into a very attractive planter. Instead of plants to spill over the sides, this one is planted with succulents some of which trail over the edges and all of them can survive in relatively shallow soil.

Plants like the Coneflowers or Lantana would not work because their roots need deeper soil than is possible in a shallow fountain basin. The succulents, of course, need to be watered to survive. They may need a daily or every-other-day splash of water. I especially like the blue-green gravel mulch around the base and in the basins.  It is suggestive of flowing water.

And my final suggestion about a waterless fountain: simply leave it in place as a garden ornament.  Most of the fountains I’ve seen are very attractive on their own.

Our 8 most popular newsletters

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