Desert Landscape Design is Combination of Art and Science

Q. We recently moved into a new single-story home and want low maintenance, desert hardy plants. The plan called for 4 Japanese Privet trees and we became suspicious. My husband and I know nothing about ANYTHING that grows and so went to Springs Preserve to ask questions. The designer there assured me they would be, "Just fine". The landscaping was completed at the end of March followed by horrific winds and the trees looked pretty battered but I figured that they would recover. But then...the heat!

Fast forward to now and we have one tree completely dead, two are looking rather ghastly and one seems to be okay. We are following the watering schedule outlined by the landscape company, 7 days a week, 2 times a day for 15 minutes each. 

We could use some guidance as to what happened and what my other possible plant choices could be?

A. You should have trusted your instincts. You're instinct was spot on when something didn't seem right to you. Let's see… You are putting in a desert landscape and using plants native to Japan... Are there deserts in Japan? Oh yes, the desert Japanese privet, I forgot about that one!

Again, I have to thank Sunset magazine for letting me use these pictures that appeared in that magazine over 20 years ago. I used them many times in classes that I taught over the years.This is an example of the Prof. Jones minioasis concept of desert landscape design. It emphasizes three watering zones; high, medium and low.

Of course, I'm joking with you and I hope you can appreciate a little humor at your expense. I have about 8 posts on my blog about using Japanese privet in landscapes in the Mojave Desert. About 4 or 5 of those are how they do not tolerate dry soils and they perform much better growing in lawns.

You did the best you could. You checked with who you thought were knowledgeable people and they assured you everything was going to be okay. Well, they were wrong.

A slide from a PowerPoint presentation I used in my classes.I am not a landscape architect nor am I landscape designer but my classes focus on water and energy conservation through exterior design.

I don't like to get involved in plant selection. It is my least favorite topic in horticulture. But the majority of these plants, and the most expensive plants on your plant palette, should come from dry climates not from places like Japan. I will forward this email to a knowledgeable person who loves this topic and she can respond to you.

But I would tell you this:

• The first question a landscape designer should ask is what your activities are outside now and what might they be over the next 10 years. This lays the foundation for creating exterior livable spaces. Plant materials are secondary to the design and used to enhance these livable spaces.
• Your landscape design should include a high, water use area, a medium water use area and a low water use area. The irrigation design reflects the landscape design and helps sustain the plants growing in it.
• High water use areas are used to help lower energy costs such as for AC and to create pleasant environments for people to use these outside spaces.
• High water use areas should concentrate on plants that shade your south and west walls. You do not need trees or plants that get above 20 feet tall for a single-story home. Plants much above that height just waste water.

Minioasis design concept and Hydro zoning rely on irrigation systems designed for plants having high, medium and low water requirements. Red is high, green is medium and blue is low.Again, thank you Sunset Magazine.

This type of landscape design concept is Dr. Warren Jones minioasis landscape design concept developed over 40 years ago at the University of Arizona in Tucson. It is talked about in his book, “Plants for Dry Climates”. This is still a valuable resource to use when deciding on a desert landscape design and plants to grow in it.

I attached some graphics for you to look at. I also included a finished desert landscape design that has a pool and lawn area. Yes, desert designs can be anything but should lower water costs, energy costs and use desert or desert adapted plant materials for the majority of its landscape.

Fruit Trees Don't Need Daily Watering in the Heat

Q. I bought this apricot tree in March and it flourished and I got lots of apricots from it within a couple months. It started to turn hot and the leaves started to turn brown I have watered it very well daily as it's exposed to full sun and it seems like it's withering and I can't figure out what's going on. Here is a few pictures of the whole tree and some of the leaves and even the bark

A. Avoid watering daily. Fruit trees do not need to be watered every day even if it's 115 F. I am watering hundreds of fruit trees that were planted in March of this year as bare root.  These trees were not in containers, and I am watering them every other day right now during this heat. But when they were planted, compost was mixed with the soil used for planting around the roots. As they were planted, water was added to the planting hole so that everything was a slurry, a muddy mess, all around the roots.

Apricot leaves will scorch more if the tree is not healthy. Make sure it's given an iron fertilizer in January or February.

Water with a hose during establishment. These trees were watered with a hose 3 or 4 times in one week before the drip irrigation was turned on. A depression 3 feet wide was put around each tree so that water from the hose would collect around the tree and the soil would settle around the roots.

Woodchip mulch. Finally, a 4 inch layer of wood chips surrounded each tree at least 3 feet in diameter. The woodchips were kept 6 inches away from the trunk so that water, in combination with the woodchips, did not rot the trunk where it entered the soil. These trees will not need to be fertilized for 2 years because of the compost used at planting time. You can get good compost from Viragrow in North Las Vegas.

Apricot tree may scorch when surrounded by rock on the surface of the soil when it is 115° F

Drainage. Take a post hole digger and create vertical holes or chimneys in the soil about 18 inches from the tree in 4 locations if drainage is a problem. These vertical holes will help drain water away from the roots and help prevent them from suffocating. Pour compost into these 4 holes and fill them. Then I would cover the soil around the tree with woodchips, not rocks, 4 inches deep. Keep the wood chips 6 inches from the trunk of the tree.

Monitor soil moisture. I would buy a soil moisture meter used for houseplants that will cost you less than $10 at Lowes or Home Depot. When you take a soil moisture reading, push the tip of the meter into the soil about 4 inches deep and look at the needle. Don't water the tree unless the needle is in the middle of the meter (5 on a 10 point scale).

Reader Not Sure What to Do with Aloe

Q. Not sure of what to do with this plant, Any suggestions?

A. Aloe doesn't like it in the same spot you might plant a cactus. It likes a little bit more protection from the sun and it also likes improved soils. I would plant it on the east side of a building or the south side if it's getting some filtered light. Northside is possible but there needs to be lots of reflected light. You can plant it in a desert landscape surrounded by rock but in a few years it might not grow very well, turn yellow and begin to dieback to the ground.

It's a succulent so you have to plant it and water it differently from a cactus. It will like more soil amendment such as compost mixed with the soil around its roots at the time of planting. You will have to water it about like a shrub growing in your yard, maybe twice a week or when you see it begin to shrivel.

Water and fertilizer. Because it is not a cactus, it should be watered and fertilized more often. I would fertilize it once or twice a year in the spring and early summer. It will respond very nicely to compost applied to the soil within 6 to 10 inches of the plant, no closer. Then water it in. Water it about every two weeks or when you see it start to shrivel.

Your Aloe vera can be propagated very easily by removing the soil around its roots and cutting off any new "starts" or pups with a sharp knife or pruning shears. If you don't do this every couple of years they will get overgrown.

They make good container plants but like I said you will have to take it out of the container every few years when it starts to get overgrown and divide it, cut off the pups for replanting. If you cut off the pups and lift them from the soil right away, put them in the shade for a day so the cut end has a chance to heal over. Don't plant it with a fresh cut.

You can also take a long sharp knife and cut the soil between the mother plant and the pup. Cutting through the soil will also cut the attachment to the mother plant. Do not lift it but leave it in the soil next to the mother plant for a few weeks. This will give the pup a chance to grow more of its own roots. Then go ahead and lift the pup with a long knife, pushing it up through the soil beneath from beneath it rather than only pulling it from the soil by its leaves. You can replant it in a container or new spot immediately.

As far as the health/medical benefits of aloe, It has a lot of uses. I think you will get a lot of comments from this post so stay tuned.

How to Produce More Flowers on Desert Lady's Slipper

Q. A long time ago I asked you for any details you might have for this somewhat gawky, but pretty plant, with its small red flowers come spring and summer.  Hummingbirds love them. The botanical name is: Pedilanthus macrocarpus. I am interested in trimming, feeding and any other details particularly to encourage more large blooms of the red flowers. We have two of these plants facing Southwest, and one is about 5 feet high and straggly.

A. I don't really know much about this plant. When I start investigating a plant, any plant whether I know it or not, I start digging for information usually from University documents and reliable nurseries. This plant has been given is "Lady's Slipper"And it is a perennial succulent.

From Mountain States Nursery

From Arizona State University

From the University of Arizona

This plant is from Baja and the Sonoran Desert. That tells me a lot. Yes it can tolerate desert soils and desert conditions but it does like to have a drink of water periodically. I also suspect this plant will grow better with a little bit of organics mixed in the soil at the time of planting. Or some organics added to the surface of the soil where there is water and let it decompose around the plant. It might also like to be misted periodically since it’s from Baja.

It seems to be tender to freezing temperatures below 30° F. It may not handle intense desert sunlight so it's best growing under trees in those exposures or on the east side of the building.

I couldn't find information on what triggers the flowering of this plant but information from Arizona State University says this plant blooms more profusely during the winter months. It remarks that summer flowers are not as striking. Flowering might be triggered by temperatures, daylength or rainfall.

So let's talk about how to get more flowers, and larger flowers, on this plant.

More flowers. The more growing points this plant has, the more flowers it will produce. Generally, pruning this plant to improve flower production should be done at its base; removing entire stems from deep down inside the plant rather than any kind of shearing or cutting off the terminal ends of the branches. 

Some of the longer stems can be cut back so that they will grow more stems to produce flowers. These are called "heading cuts". One heading cut will produce 3 to 4 new stems that can produce flowers.

Fertilizer. I believe in the use of compost for soil improvement and adding nutrients, fertilizer, for the plant growing in desert soils. Apply perhaps one quarter cubic foot of compost to the soil at the base of this plant in early spring. Try supplementing this plant with a high phosphorus mineral fertilizer such as triple super phosphate or bonemeal. 

Apply all fertilizers containing nitrogen in half rates the label states. Begin applying phosphorus fertilizers about two weeks before it is known to bloom. Do not apply any nitrogen fertilizers or compost after August 1 through November.

Sunlight. Make sure it has at least 8 hours of sunlight. Keep it out of spots where it has intense sunlight such as your walls facing West or South.

Water. Water it sparingly as you would a desert plant, but deeply when you do. Try watering once every 2 to 3 weeks. Use its growth as an indicator whether to water again. If it's not pushing a lot of new growth, water it more often. Apply water a distance from the plant equal to up to at least half of its height.

Drainage. This plant must have good drainage or it will die or fall over.

Privet Tree Leaves Black Spots are Disease? No.

Q. I'm sending you a photo of a leaf from my privet tree that has some kind of fungus. Can you suggest some fungicide for me to use?

Spotting on privet leaves. It could be a disease problem but it would most likely not be
there if the tree was getting proper care.

A. I think it is just a lack of good nutrition and perhaps a lack of adequate watering rather than a disease caused by a pathogen like a fungus. Even if it were a fungus disease, it is more susceptible to disease if it is in poor health. However, too much irrigation water applied too often can look similar to this.

            Not enough water usually results in leaf drop in the early stages of stress with this tree. I will post your picture on my blog for readers to see your particular problem.

            Japanese privet does much better in mixed landscapes rather than alone in rock mulch, if you have it in rock mulch. They do not like soils that develop in a rock environment and have trouble picking up the right nutrients from these types of soils to stay healthy. Please be aware that this tree is not a desert plant so it will require more care to keep it looking good.

EDDHA found in the ingredients of an iron chelate fertilizer

            Without soil improvement you might try giving it a better fertilizer product. Fertilizers for trees and shrubs from manufacturers such as Miracle Gro, Peters, Jobe’s fertilizer spikes and others will provide better nutrition for the plant than using an inexpensive agricultural fertilizer. Add to this an iron product that contains the EDDHA chelate (look at the ingredients).

            Specialty fertilizers like these are not inexpensive. However you can save some money by not using it each time you fertilize. You can make an application and then boost plant performance by using just a little bit of nitrogen fertilizer when the plant needs it.

            But if the plant is in rock landscape you will need at least one expensive fertilizer treatment annually to improve your plant performance under the poor soil conditions of rock mulch landscapes.