Desert Horticulture Podcast: Maintaining a Lawn in the Desert

Maintaining a lawn in the desert is not easy. Learn the fundamentals of desert lawn care: irrigation, fertilizing, mowing, aerification and dethatching.

Deseert Horticulture Podcast: How to Establish a Lawn

Lawns are sometimes a necessary part of a desert landscape. And when you are finished with it, the soil is improved and its easy to replace. Learn how to establish one in our desert climate.

Hearts and Flowers Failure

Aptenia, or Hearts and Flowers, is a succulent that looks good with a little bit of shade and not in full sun unless the soil has been amended well.

Q. This spring we re-landscaped our yard to include six groundcover plants called Hearts and Flowers groundcover planted in full sun. They did well in the cool, rainy spring.  As the weather got warmer, most of them turned brown starting at the center of the plant and extending outward.  They are watered with two each, 2 gallon per hour emitters for 30 minutes three times a week.

A. It sounds like it just got too hot for them in that location. These plants are short-lived in the desert. Hearts and flowers are succulents and not as tough in full sun as many cacti. They grow best in the cooler months of spring and fall. They originate in the warm and dry parts of South Africa in locations that have summer monsoons.

            Hearts and Flowers will grow in full sun out in the open if it is not a southern or Western exposure with reflected heat. Plants will handle heat better if they are planted in soils amended with good compost but prefer light shade in the afternoons. The best place to put them is morning sun with some light shade in the afternoons or on the east facing side of a wall. Typically, they have very few pest problems.

           

Fall Annuals to Purchase and Plant from Seed

Q. As much as I love them, the geraniums are just too high maintenance for me this year. Gave up on them. Can you recommend something, in addition to Lantana, that is colorful and low maintenance?

A. Like vegetables, flowering plants have a time of year when they perform best. Lantana is generally a summer flowering woody perennial while geraniums flower best in our climate, even though they are perennial, during the cooler months of October through March. The usual planting dates may vary somewhat with the weather, but it should be around early to mid – October.

Commonly Found Geranium Alternatives

Some common alternatives for geraniums used as annuals during the winter months include Snapdragons, Pansies, and Petunias planted with Alyssum and Lobelia. Even though they aren’t true winter annuals, they grow best during the cooler weather of mid fall through early spring.

Start Fall Flowers from Seed

Some fall flowering plants for fun that you can start from seed include 

• Alyssum (L)
• Bells of Ireland (T)
• Calendula (M)
• California Poppy (L)
• Candytuft (T)
• Cornflower (M)
• Gilia (L)
• Godetia (L)
• Iceland Poppy (M)
• Larkspur (T)
• Lupine (M)
• Nemesia (M)
• Nemkophila (L)
• Pansy (L)
• Phlox, Drummondi (L)
• Pinks (L)
• Stocks (M)
• Snapdragons (M)
• Verbena, Sand (L)
• Verbena (L)
• Viola (L)

L=Low   M=Medium Height   T=Tall

Many of these will self-sow themselves year after year.

Big in the Back

Pay attention to their mature size. Taller plants go in the back of the planting area and smaller plants go in the front. Before planting any of these non-desert flowering annuals, mix a decent compost into the soil before planting if it’s going in a bed.

Amend the Soil Each Year and Fertilize Regularly

 A 1-inch layer of compost mixed into the soil 6 to 8 inches deep annually at planting time, just like a vegetable garden, is enough. If the compost is a dark brown or black amendment “rich” in nutrients, don’t add any fertilizer at planting time and for the first 2 to 3 months after planting. If the compost is not rich, mix in a high phosphorus fertilizer with the compost just before planting.

Deadheading

Deadhead these plants regularly. Removing spent flowers produces more flowers and extends the life of the plant. Fertilize these winter annual flowers lightly with a high nitrogen fertilizer once a month.

Pine Tree Not Growing

This pine is struggling. Notice the open canopy, how thin it is.  It is either not getting enough water or it was rootbound at planting time. 

Q. Several pine trees on municipal park property provide privacy from people who frequent the adjoining park. All these pine trees have done well over the last 20 years except for one that is about half the size of the others. It’s in a perfect spot to provide privacy for me but doesn’t because of its size. It gets plenty of sun and is not overcrowded by other trees, but I don’t see any water for any of them. How do I help the little guy pine tree get to the same size as his big guy brothers?

This pine tree is getting enough water. Notice how full and dense the canopy is.

A. All those pine trees are irrigated, or they wouldn’t survive in our desert climate and put on decent growth year after year. The smaller tree could have a problem all its own, separate from the others.

Is it Rootbound?

            The fastest way to find out is to push hard on the tree trunk. You may have to push several times. After these many years, that tree should be solidly anchored into the ground. If it’s loose in the soil, the tree has a rooting problem and should be replaced. If a tree with this problem is not replaced, it will always be small and never grow regardless of what you do.

Plants that are rootbound can end up with strangling roots that choke other roots. These can be removed with they are young. Be careful when the roots are large.

            When you push on it, there should be no soil movement where the trunk enters the ground. If you do see movement beneath the trunk, the tree was “root bound” when it was planted and never became established in the surrounding soil. That would be unfortunate, but this happens too frequently to landscape plants grown in containers.

Plants left in containers too long can create root problems.

            “Rootbound” plants have roots that grow in circles inside the container. This root growth problem begins when plants are very young and is seldom a problem that develops when they are older.

            It is possible plants can become “root bound” if they are grown in a container which is too small for them for too many years. I suggest consumers don’t focus on the “largest trees they can find”. Smaller plants, that are healthy and growing rapidly, are always a better choice and will establish in the landscape faster.

Lack of Water

            Another possibility is a lack of water. Inspect the soil to make sure that irrigation is not the issue. If the plant is not root bound, water the soil under the canopy of the tree with a hose, sprinkler and mechanical timer for one hour, once a week. Do this during the summer months. Fix the irrigation problem of course but the extra water once a week will help push new growth faster.

            Fertilize pine trees once a year in the spring with a tree and shrub fertilizer such as 16-16-16 or 20-20-20.

Microclimates in the Desert are Important

Some people think I’m crazy when I mention the importance of microclimates in landscapes. Others may be unsure about what they are, how to establish these microclimates and if they’re worth the expense. It’s really whether you value the selection, appearance and quality of plants growing in your landscape.

This microclimate was established next to a hospital on Maryland Parkway in Las Vegas. It is sunken, protected from Maryland Parkway traffic on the left and its noise. It also gets several hours of midday sun and the smaller plants and the ground protected from late afternoon sun from the West (left). This makes an area for employees where there is less noise and cooler.

Microclimates affect how plants grow and appear in the desert, their quality if you’re talking about vegetables growing in raised beds or fruit on fruit trees and how comfortable we are when enjoying a beverage or meal outside. Landscape microclimates change something about the outside: the air temperature, wind speed, humidity, noise level or may address privacy issues. All these change the microclimate in an otherwise open landscape.

Some construction going on so the yellow cord is there but plants that might normally struggle in rock due to the heat and intense sunlight perform better with a break due to a microclimate.

A recent stroll through a commercial property on Maryland Parkway reminded me how important these changes can be for plants and for us. A section of this commercial property lowered the strolling and sitting area below this north to south running street. This change provided morning and afternoon shade, change the direction of the wind and lowered wind speed and reduced the noise level from passing traffic 20 feet away.

Plants like this Japanese privet perform better where they have a break from the intense desert environment.

Here I found outside sitting areas enjoyed by employees on a hot morning. I found plants thriving, compared to their struggling counterparts 50 and 75 feet away. A simple lowering of the landscape elevation provided “comfort” for plants and humans alike without changes to the soil or irrigation different from the rest of the landscape.

Plants like this daylily planted in rock looks much better than its counterpart planted along the street.

Be Creative with Microclimates at Home

Changing the landscape elevation is one way to address problem areas. Other methods include trellising, building wind screens or diversions, use of gazebos, building partial walls, using manufactured screening, paint and other methods that provide a microclimate that improves the quality of plant growth and the outside living area. Remember that cement and steel are more durable surfaces than wood in the desert.

            I will talk more about this subject on my podcast.

Lawn Dies in Midsummer

Q. My father’s lawn is tall fescue and completely went dead this summer. I’d like to know what we did wrong because we watered twice a day. We are anxious to plant a new lawn ASAP and want some advice on how to plant a new lawn from seed and the best seed to use. The lawn gets full sun.

A. Whatever killed the lawn is most likely gone. I know you watered twice a day, but death of an entire lawn during the summer is nearly always due to an irrigation problem. There are diseases and insects which cause damage, but they always leave behind telltale patches of green. These patches of green, to a trained eye, are clues to the cause of dying grass.

Lawn disease

Leave it Alone

            Wait until the temperatures cool down a bit, perhaps sometime between late September and mid October, to begin planting a new lawn. In the meantime, leave the dead grass in place to shade the soil and prevent weed growth. This layer of “mulch” reduces weed problems that might pop up if you were to remove it. In the meantime, continue irrigations because there are probably plant roots in that dead lawn that need the water.

Lawn brown spots due to irrigaiton

Check Irrigation

            Check the irrigation system and make sure it's working properly and the irrigation controller is functioning. Kill and remove any weeds in the new lawn area. If using a weedkiller, spray a week in advance so the herbicide has time to disappear before planting.

Soil Prep

The day before planting the seed, irrigate to soften the soil. Rent a core aerator to punch holes all through the lawn area and rake it to remove or break up these cores. 

Reseed and Topdress

            Apply 10 pounds of fescue seed blend per thousand square feet of lawn area. Don't skimp on the cost of grass seed. Good grass seed is expensive. Bad grass seed is cheap.

Fertilize or Not

This is also the time to apply a fertilizer on top of the grass seed if the compost is not a “rich” compost. If the compost has fertilizer in it (a rich compost), don’t apply any fertilizer. Cover the seed with a 1/8-inch layer of compost and water twice a day. When the grass starts coming up in about five to seven days, reduce irrigations to once a day in the morning.

Mow to Thicken the Lawn

            You will see grass emerge first in areas where there is good irrigation coverage. Where the grass is growing slowly, work on improving the irrigation system for better water coverage. Mow the grass no closer than 2 inches when the grass reaches 3 inches tall. Mowing causes the lawn to become denser.

Tomato Theft Might be Rats

Q. I have a raised planter box with my tomatoes doing quite well. Some critter is raiding these tomatoes nearly every night and removing the fruit. I found one of my larger heirloom beauties half-eaten and dropped outside the box about 20' from the plant! What kind of critter might be big enough and strong enough to do this?

I think this is ground squirrel damage to the fruit but the incisor damage would be similar to a rat.

A. I would first suspect rats. Rats are common throughout the Valley, probably the second worst problem after birds, and they will eat anything from fruit and citrus to vegetables including tomatoes and even fresh compost ingredients. Normally, though, they eat fruit still attached to the vine, but they can carry the fruit if they must. But damage to the fruit, because of their teeth, is telling.

Not a tomato but Hachiya persimmon with bird damage. Notice the distinct bird pecking in the fruit.

            The two types of rats present are the roof rat and Norway rat, with the smaller roof rat being more common. Regardless, these critters go after ripe, or nearly ripe fruit. If food becomes scarce, then these critters will go after unripened fruit as well.

Southern Nevada Health District and Rats

            Two nonlethal strategies that might work include getting rid of any hiding places such as low-lying and dense shrubbery or piles of debris and harvesting fruit before it becomes fully ripe. Harvest tomatoes when they are still green, provided the green fruit is starting to change color, and they will still ripen off the vine. This color change occurs first near its attachment to the mother plant, called the “shoulder”, and spreads over the rest of the fruit as it ripens. Harvesting fruit early reduces the chance critters will eat them.

            Rats are good climbers so if you enclose a tomato plant with a cage to restrict their smorgasbord opportunities, use hardware cloth with holes smaller in diameter than your thumb but large enough to allow pollinator entry.

            There is a lot of information on the Internet concerning repellents from mothballs to Fox urine. Like any information on the Internet, you are likely to have mixed results so be aware.

            Regarding lethal strategies, snap traps seem to work the best and maybe the safest method to use if other animals are around.

Apply Fertilizer to Trees When it Cools Off

Q. How much fertilizer should I give my trees in the landscape and when can I do it?

A. Apply fertilizer to established, winter hardy landscape trees late in the season when temperatures have cooled down, trees aren’t growing anymore but they still have leaves. This is called a late fall fertilizer application and substitutes for a spring fertilizer application. In the Las Vegas Valley this would be around late October to the middle of November.

            Apply it to the soil after an irrigation by using a sharpened, round nosed shovel. Push the shovel into the ground as deep as you can and push it forward. Drop a half cup of this fertilizer in the slit made by the shovel and close the slit with your foot.

            If the trees canopy is 10 foot in diameter, use two half cups of fertilizer, one on each side of the tree, 2 feet from the trunk. If the trees canopy is 20 feet in diameter, use six each, half cups of fertilizer, three on each side and spaced about 2 feet apart. If the trees spread is 40 feet in diameter, apply 24 of these half cups in wet soil under the canopy. Turn on the irrigation water in a normal irrigation cycle, let it dissolve the fertilizer in the soil and carry it to the roots.

Skeletonizer Damage on Tecoma Can Look Like Drought

Q. From a distance I thought my Yellow Bells and Orange Bells shrubs weren’t getting enough water because the leaves started turning brown. But when I looked closer, I’m wondering if the brown leaves are because of a fungus on the leaves.  Any thoughts?

A. Look at the leaves of your Tecoma, a.k.a. Yellow or Orange Bells, more closely and I think you will see that the surface of the leaf has been eaten or “skeletonized”. This chewing damage causes the leaves to turn brown; they become brown faster when it’s hot out. At a distance you see the leaves of your Tecoma turning brown and it may look like drought.  Upon closer inspection, you get more detail and can see the insect damage to the leaves and not a disease.

Skeletonizer damage on Tecoma spp. Yellow or Orange bells

            This shrub is native to the Sonoran and Chihuahua and deserts of the Southwest, all through central and even the northern parts of South America, but not the Mojave Desert where it needs slightly more water and warmer winter temperatures. Tecoma and this skeletonizer coexist together. The skeletonizer is the younger stages of a moth. It’s not clear if this insect will survive the low temperatures of our winter or not. If it does, as more Tecoma are planted, we may see more of this insect damage in future years.

Orange bells

            This insect damage is common to Tecoma in warmer parts of the Southwest. It’s feeding damage by the young, a.k.a. larvae, of a moth given the common name Tecoma Leaf Tier Skeletonizer. This damage is like the skeletonizer damage we see on grapes but caused by the young of a different moth.

In-depth treatment of this insect

            Right now, this insect doesn’t usually cause enough damage to warrant spraying an insecticide. Just pull off leaves when damage appears and drop them on the ground. If the damage gets worse in future years, then spraying might be warranted.

            The pesticides of choice are “natural” insecticides called Bt and Spinosad. Apply these sprays just before you anticipate damage or at the first sign of damage. Bt and Spinosad products will kill the larvae of any moth or butterfly, whether it’s good or bad one so be careful.

            Spinosad can be hard on honeybees so don’t spray plants that are flowering and spray at sunup. If you have no choice when to spray, and the plant has flowers, remove them and more flowers will be produced later.