On my continuing travels through Louisiana, I have noticed that few homes have anything that resembles a garden with shrubs and flowering plants artfully arranged. The more common gardening feature is the lawn, a large mowed green area around the home. Upon taking a closer look, I realized that many “lawns” are simply native grasses and other low growing plants sheared to slightly above ground level. It is an act of self-defense. Extremely fast-growing native shrubs and trees take over every space that is not regularly cut back in this hot, damp climate.
A garden has been planted around the Oplousas Louisiana courthouse including purple and pink Crepe myrtles.
The exception to this emphasis on lawns, are the Crepe myrtle trees (Lagerstroemia indica) planted by homeowners. They are ubiquitous.
These natives of southern China were introduced into Charleston, South Carolina by plant explorer and botanist to King Louis XVI, André Michaux, in the mid 1700s. The name is sometimes spelled Crape myrtle, but Crepe myrtle now seems preferred. Whatever the spelling, they took the South like wildfire. People loved them.
This hot pink color seems to be the most popular Crepe myrtle. It is a bright contrast to the green of the South and the brown of the southwest.
And Crepe myrtles loved the heat, lots of sunlight and the slightly acidic soil.
Some newer hybrids have been developed to tolerate chillier winter conditions, including frost. And–surprisingly–they are somewhat drought tolerant.
Correcting alkaline soil conditions
It’s that “acidic soil” part that is an issue in a hot, dry climate. Most of the soils in the desert Southwest are alkaline, but alkaline soils can be corrected to a soil condition that Crepe myrtles love in two ways:
Add 4 to 6 inches of organic mulch and dig it in to a depth of one foot. Within a year or two the soil will become more neutral. Mulch should be added every year.
Add sulphur to the soil and dig it in which will also balance the pH. While this maybe a faster way to rebalance soil, be very careful with this because too much sulphur can be harmful.
And be sure to deep water your Crepe myrtle tree at least once a month in summer. Drought tolerant doesn’t mean “no-water-required.”
Here are some Crepe myrtles I’ve admired in Louisiana:
Two colors of Crepe myrtles planted together. The neighbor, behind, planted a white one which is now at least 25 feet tall.These Crepe myrtles have been carefully pruned to allow an open area beneath them on the University of Louisiana campus. Their broad growth is a characteristic of the hybrid. Some hybrids grow tall and narrow, some broad, and there are dwarf hybrids that are perfect for hedges.White Crepe myrtle trees are less common than the various shades of pink and purple. This one was ladened with white flowers. This home actually has a small garden planted around it!
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.
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 alarge 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!
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.
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.
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.
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.
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