Tag: Fall planting in hot dry garden

Follow the 90 degree rule for planting

Fall is definitely the best time to plant in hot, dry Western gardens. It’s actually a good time to plant in much of the world, because, after all, Fall is when Mother Nature sows seeds.

But not just any Fall day will do. In the desert southwest, including parts of Texas and California, you should wait until the average daytime temperature drops under 90F before you plant.

The issue isn’t only the air temperature, but the temperature of the ground. The soil, especially native soil, is far too warm now for the roots of transplants to grow. Between the dehydrating effect of the air temperature on new leaves and the “cooking” effect of the hot earth on the roots, new transplants may not survive very long even if you water them frequently.

How to protect your transplants

Clematis in bloom
The Clematis jackmanii in my backyard.

However, if you just can’t wait to start gardening again after a summer hiatus, you may be able to protect your transplants by placing a piece of tile or broken terra cotta pot over the root zone, thus keeping it cool.

I did this with a Clematis Jackmanii, a plant not commonly found in a hot, dry garden. I planted it by a trellis in a very sheltered corner with a broken piece of pot over the root zone. It grew and bloomed then over winter it died back. The following spring it rose from the seemingly dead to climb the trellis and bloom again. To see other climbing plants for hot dry gardens, to here.


You could also add shade cloth to help reduce the temperature.

Should you avoid planting in native soil?

I have to admit that the Clematis was not planted in purely native soil. In most of the Southwest the soil is alkaline and lacking many of those tasty chemicals that hungry plants need. Realizing this, I made sure the Clematis was installed in a flower bed with super-enriched soil made mostly of organic mulch. And remulching twice a year is a must with our poor quality dirt which leeches all the good chemicals out of the mulch into the dirt within months. “Poor dirt” returns to being “poor dirt” rather quickly.

Another approach is to plant in raised beds, but those large wooden or metal boxes can become rather expensive. So, consider going to Amazon to find grow bags for a more affordable solution.

They come in small, medium and large and are good for growing almost every type of vegetable or herb. You can fill these bags with soil you buy at the garden center or mix native soil into the bag with commercial potting or top soil. And all the good, nutritious chemicals in the growing mixture end up feeding your plants — not dissolving into the surrounding soil.

Playing for Julia ebook

Prickly Pears may save us all

Well, I’m late with this, but according to a five-year study at the University of Nevada Reno, those ubiquitous prickly pear cacti (Opuntia) can become a new source of bioenergy feedstock to replace fossil fuel. This cactus also does double-duty as a land-based carbon sink removing carbon dioxide from the atmosphere and storing it in a sustainable manner. Just like trees do.

This is especially important because, according to a biologist at Saguaro National park as the climate in Arizona and around the world is changing prickly pear cacti are becoming more common. They really like the new weather conditions and poor quality soil is no problem for them. So add a prickly pear to your garden to help with the changing climate. And keep in mind that prickly pear jam is delicious!

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

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Is that plant dead? Should I replace it now? Tips for Fall planting

Mother Nature plants in the Fall and so should you.  Instead, however, of simply deciding which trees, shrubs or perennials to add to your arid garden this Fall, you may be looking at which plants you need to replace. The record-breaking heat in the Southwest and California (and Australia!) this last summer baked the leaves on many plants and turned them brown  overnight. On others the leaves simply fell off the branches. The plants appeared dead.

Azalea regrowing after sunburn
After looking as if nearly dead, the cooler weather has brought new growth to this white azalea which thrived for years in a micro-climate backed up against a wall in almost total shade.

But don’t yank these sunburned plants out of your garden yet, especially now that the rains have come. Wait two or three weeks. The roots of dead-looking plants may have survived the heat and be ready to regrow.

If, however, you decide to replace some plants, consider the suitability of the ones you choose for replacements. The heat this last summer will probably be back next year and for many summers to come.  You may want to select more desert-like plants or take steps now to create micro-climates for parts of your garden that suffered most from the heat by adding shade-producing and heat-reducing plants.  And, unlike the Beanstalk of Jack-and-the-Beanstalk fame, the plants to create micro-climates don’t grow sky high overnight. Planting them this Fall–rather than waiting until Spring–will give them a head start on growth over the winter.

Plant now to create micro-climates in your garden

For starters you can help cool off your entire garden by planting a fast-growing hedge in front of a hot wall. This can be effective with both cement block walls around your property and  the stucco walls of your home. The shrubs’ leaves will block the sun from heating up the wall during the day so there will not be as much drying heat to be released after dark.  Overall your garden will feel cooler and a bit less dry.  And a cooler, slightly damper garden is better for all plants — and people.

Two drastically different hedge plants that grow fast are Pampas Grass (Cortaderia selloana) and Japanese privet (Ligustrum japonicum).

pampas grass
Behind this Pampas grass is a dull gray block wall. In one year it was covered up.

Pampas grass is close to being a Jack-and-the-Beanstalk plant. It will shoot up to as tall as 20 feet in one year, and should be cut back to 18 inches high in mid-winter.  But be aware: its blades have rough edges that can cut skin so wear gloves when cutting it back. And it may be very difficult to remove if you change your mind later. It is definitely a statement plant.

Ligustrum japonicum privet hedge in bloom
In Springtime the Japanese Privet hedge bursts into bloom.

The Japanese privet is more ordinary looking–just a basic green hedge.  It grows about two feet a year, however, and is quite drought tolerant. Poor soil conditions do not seem to bother it either. In Spring it is covered with white flowers that look almost like lilac blooms, but don’t smell nearly as nice as lilacs. You can see these and other shrubs for hedges in arid gardens here.

Planting a tree for more shade is another way to create a micro-climate to help other plants in your garden survive in hot weather.

Chitalpa taskentensis flowers in summer Hot Gardens

One rapid growing tree that is suitable for arid gardens is the Chitalpa (Chitalpa tashkentensis) which will grow about 3 feet a year to a maximum height of 25 feet.  It is a hybrid of the Desert Willow and the Catalpa tree that was created specifically to thrive in hot, dry climates.  While it likes balanced soil, slightly alkaline conditions will not impair its growth. I especially like it because it has long-lasting, pretty pink-white blossoms, an open branch structure and provides dappled shade, rather than dark shade. You can see other trees for hot, dry gardens here.

The right way to plant a tree or shrub

The hole for planting should be 2 1/2 times as wide as the root ball, but do not make it deeper than the root ball.  The crown (the part where the roots meet the trunk or main stem) should be at or slightly above ground level–not submerged in the hole.  Be sure to add a lot of rich organic mulch into and around the hole you dig for a new tree or shrub to provide nutrients for growth, especially root growth during winter.  Really soak the soil with water around the planting hole and, once planted, water the tree regularly until the plant is established.

Now here is one last recommendation for coping with our hotter, drier summers and the damage of relentless heat. In my last post I wrote about applying organic mulch around plants, trees,  and in flower beds to help supply nutrition. Another benefit of mulching  is that mulch provides an insulating layer to protect the roots from scorching summer heat and winter cold.  That’s right — winter cold and its potentially damaging effect on plants is right ahead of us now. More about this in an upcoming post.

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