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Monday, January 4, 2021

Should Pine Trees be Grown in the Desert?

The major uses of pine trees in desert landscapes are for visual barriers, sun protection, windbreak, or mark property boundaries. 

Problems with Pines

They oftentimes become too large for the property. Cute when they are small. That is the problem now, they are large trees so you need a lot of space to grow them. And they use more water as they get bigger. And they need to be watered deep to improve their anchorage during strong winds. There are plenty of other choices that are smaller trees for shade and for visual barriers. As windbreaks? Put windbreaks close to where they are needed,  not on boundary lines.

Pine trees are frequently planted for shade but out of scale when they mature.

The two pine trees most commonly planted here, are the more formal looking Afghan (Pinus eldarica, sometimes called Eldarica or Mondell or Mondale pine) and the loosely structured and informal Aleppo pine (P. halapensis).

Aleppo vs. Mondell

The less formal looking Aleppo pine (P. halapensis)

The more formal looking, Christmas tree-like, Mondell pine (P. eldarica)

These can be fairly large trees at 40 feet tall and above and can easily dwarf a single story home. They can use quite a bit of space and, at those sizes, can use quite a bit of water when they get bigger. Its not a question about whether they will grow in the Mojave Desert but where will you put them?

Aleppo Pine Blight

They can look quite similar sometimes and telling them apart can be difficult. All pine trees can cross pollinate and are wind pollinated. But most of the time they are easy to recognize. One method I use to differentiate the two is the presence of winter physiological disorder called Aleppo pine blight. It only is present on Aleppo pine. It usually causes isolated browning of new growth in a patch or two here and there. In some cases, it can cause tree death but it is rare in Las Vegas.

Aleppo pine blight occurs during the winter and is a disorder that oftentimes causes isolated browning of new growth in Aleppo pine only. It can get so bad in some regions that it causes severe browning and suspected of tree death.

Chir Pine?

A vert large (60+ feet) and graceful pine sometimes used is the Chir pine (P. roxburghii). But this pine is a bit tender to winter cold (and in severe freezing temperatures (low 20's) can be damaged. Like many other plants, in its wild native habitat in the lower elevations of the Hindu Kush (northern India, Afghanstan and northern Paksistan) survives fire and will "sprout" new growth from its trunk if scaffold limbs are killed by fire or cold. Not to be confused with a very similar looking, long needled, but more winter tender pine called Canary Island pine (P. canariensis) heralding from...you guessed it...the Canary Islands.

Chir pine, considered perhaps subtropical, can be a bit tender in the Las Vegas area but it has a very graceful appearance if it survives the winter cold every 15 years.

Chir pine is one of the "long needled" pine trees that can have a very graceful appearance in the landscape but not nearly as tender as its very close relative, the tropical Canary Island pine and similar in cold hardiness to some of the more tender citrus like naval orange (P. canariensis)

This Chir pine survived but some of the branches froze. The mass of its trunk survived the freeze and sent out these suckers from epicormic buds embedded in the trunk. Fire and freezing temps can cause the same reaction.

Japanese Black Pine

Japanese Black pine is oftentimes recommended for planting in urban landscapes because it is a smaller pine (25+ feet) with an interesting form for landsapes. But when was the last time you saw one growing here? Nearly all of them planted here have died. Beware!

Japanese black pine.

Two Nevada State Trees

Bristlecone pine (P. longaeva) and Pinion pine (P. monophylla) are the two state trees of Nevada. Pinion pine occurs at around 4500 foot elevations in Nevada. Bristlecone pine much higher. For this reason, Pinion pine would  have a better chance in the hot, lower elevations of the Mojave Desert than the 6000+ foot elevation Bristlecone pine. Pinion pine occurs in the wild along with Utah juniper. The problem? Availability. It was popular for Mojave Desert landscapes about 25 years ago and disappeared from nurseries.

If you choose to grow pines in the desert:

  1. Give them plenty of room to grow because they will be big trees.
  2. Amend the soil in every direction around the trunk about 2 to 3 feet and a foot deep.
  3. Cover the soil after planting with 3 to 4 inches of woodchips.
  4. Water them with a coil of drip tubing or basin filled with water. 
  5. Water them deep when you water - three feet deep!

Shade Cloth and Other Effects of Light on Plants

Sunlight can be very strong in the desert. In other parts of the country where sunlight is more "normal", shade cloth might not be needed. Desert sunlight can be very intense at times. It makes sense with some plants to reduce light intensity with shade cloth? But how much? Which plants?


The effects of sunlight (or light) can be broken down into the quantity of light plants receive and the quality of this light. Light quantity refers to its intensity, or how strong this light can be. 

Intensity of sunlight refers to the quantity of light plants receive. Some vegetables give us better plant parts with a little bit of shade. This is 30% shade which is about right for a lot of leafy vegetables growing in the intense desert sunlight. This may be too much shade for some flowering vegetables like okra.

The 30% shade cloth was doubled over to give 60% shade in this darker area of the grow tunnel. Usually anything above about 40% shade will prevent a lot of vegetable growth and production.

Light Color

The color of light can also affect plant growth. Red light promotes flowering while solid blue light discourages flowering. Research has demonstrated that different colors of light in combination can promote certain types of plant growth. Should you as a homeowner use different lights? Probably not but it might be worthwhile if you grow plants commercially.

For more information look at https://sensing.konicaminolta.us/us/blog/can-colored-lights-affect-how-plants-grow/

At Dave Wilson Nursery near Modesto, CA, here red shade cloth is applied to influence plants.

How Long Light Shines (Photoperiod)

Plants will do different things sometimes at different times of year (mostly in cold climates, rain can play a similar role to light in tropical climates). Sometimes this is tied to how much night time there is or how much rain. Plants cant move around so they are much more "in tune" with their environment and "reading" it.

At this marijuana production facility light is used to provide the energy needed for plant growth. A certain light intensity is needed if any kind of production is needed.

Although not done here, a specific color of light could be used that enhances root production of these cuttings. Some decisions are better made considering the economics of production.

Crop Calendar for Yuma, AZ, USA.

 Yuma AZ is warmer than Las Vegas. Yuma sits on the border of Arizona and Mexico. Its latitude sits between 32 and 33 degrees North latitude (Las Vegas is closer to 36 degrees north of the equator). 

Yuma's elevation is only about 140 feet above sea level (Las Vegas is about 2000 feet above sea level). Both elevation and latitude play major factors in determining winter low and summer high temperatures.

Latitude and Longitude map of Arizona. Yuma AZ is near the border with Mexico and at 140 feet of elevation above sea level. Tucson AZ, even though lower in latitude than Yuma, is at 2400 feet of elevation above sea level which accounts for most of  its colder winter temperatures and warmer summers. https://www.mapsofworld.com/usa/states/arizona/lat-long.html

Because of its warmer winter temperatures, Yuma can grow some of the more tender nopales (such as Copena V1 and F1 and better tasting!) from Mexico than we can in our colder winters in Las Vegas. We can grow cold hardy nopales but they are not as tasty as the more tender Copena types. Winter freezing temperatures affect both pad (nopales, nopalitos) and fruit (tuna) production.

Freeze damage to Copena nopales growing in Las Vegas during the winter of 2007-8.

To make the planting/harvesting adjustment from Yuma to Las Vegas, consult local temperatures but it will be about 6 weeks forward in the spring months and about 6 weeks backward in the fall months.

Even though this crop calendar is for seed production, the planting dates would be the same.
 "Contracting" refers to the business arrangements needed for seed production to begin. "Sowing" refers to planting time.

Sunday, January 3, 2021

Are Food Forests the Right Thing to do In the Desert?

 Come join me in this podcast about exploring Food Forests in the Desert. Should we pursue this permaculture concept in desert landscapes?

Moringa leaves on our farm in the Philippines. We use the leaves of this tree for food and as a spice nearly on a daily basis. They are a commonly planted tree now in Southern Nevada due to food forests. But is it the right thing to do?

Friday, January 1, 2021

Bottle Tree and Leaf Drop

Q. Our bottle tree in Scottsdale is 11 years old and this summer had a crazy amount of leaves dropping. So, we watered longer but only once a week. It also gets some water when the lawn is watered, and right now, that is 3 times a week. The leaves are very, very light green, turning brown on the edges first and then completely brown and then dropping leaving it very sparse. Are we not watering long enough, or is it getting too much water?

Bottle trees sold in the nursery are not really a bottle tree. Yes it has a tapering trunk but the REAL bottle tree has a trunk shaped like a bottle! It may drop its leaves naturally when the soil is dry or just before it starts to flower in the late summer or fall.

The true bottle tree (B. ruprestis) has a much fatter trunk, shaped like a bottle.

A. These trees normally drop leaves just before flowering at the beginning of their wet season. In Australia where they are native, that would be just before our fall months. Many “south of the equator” trees don’t pay any attention to their new environment and flower or drop their leaves just like they were growing south of the equator. If leaf drop occurred starting around September and got worse a few weeks later, their leaf drop may be a response to longer nights, something totally out of your control.

Maximum/minimum temps in Scottsdale, AZ, USA.

Maybe it Was to Hot

Our normal summer temperatures are are about 10F hotter than their maximum high temperatures where they grow naturally. In their natural environment, the beginning of Australia's monsoon season mean cooler temperatures. With these high temperatures and low humidity and if there was a some wind then it would mean the plants and soils would dry out sooner. Your tree may have got hit with a double whammy; high temperatures and intense sunlight.

You did the right thing. You increased the amount of water they received by increasing the amount of water and not the frequency of water application. The only thing I would add is to increase the area where water is applied and not just the amount while all the time not letting the soil dry out between irrigations. My guess is the tree was getting most of its water (and fertilizer) from the lawn. That’s also probably were most of its roots are growing.

These trees like to have their "toes" in water but not submerged. Next time this happens, try watering your lawn a little more often. I think the amount of fertilizer the lawn is getting is plenty for this tree.

Bottle Tree with Droopy Limbs and What To Do

Q. I have several bottle trees that have grown well over the last years and one that has always had a slight “droop” to the branches. I’m not sure what else to do as all the other trees are doing great!

When young, many trees have upright growth. It is very common in young trees. Remember, Kurrajong (aka Bottle tree in the US) can reach 55 feet tall!

A. If the tree otherwise looks healthy there may be nothing you can do about it. Growers of bottle trees usually start them from seed. Propagating plants directly from seed creates a lot of tree variability in their growth habit, flower color, seed pod as well as the seed itself. The result is that some trees are more upright than others, some have different leaf color, and some more resistant or susceptible to disease or insects. Its genetic and nothing much you can do about it.

Trees grown from seed can show quite a bit of genetic variability in their shape, leaf color, overall size, size of acorns, leaf size and other visible traits. That's not even counting what you cant see!

Other trees propagated from seed include southern live oak, and most of our pine trees. So, you see, this variability can be good, or it can be bad if you don’t like it’s looks or it’s more susceptible to a disease present in your locale.

If you are not careful in your watering, the canopy can drop leaves or maybe some limbs might sunburn and die.

When trees are young, they oftentimes grow more vertically. They want to get taller and get taller than any competitors nearby. As they get older, vertical limbs become more horizontal. It’s possible this is what you see. When it has a full canopy of leaves then horizontal limbs are not a problem. The dense canopy of leaves shade these thin-barked horizontal branches. But if there is leaf drop from disease, insects, drought or normal leaf drop then watch for sunburn on these very susceptible limbs.

Because they are native trees, they don’t need a lot of fertilizer. Native plants are like that. They are not commercial hybrids that rely on more soil nutrients applied by fertilizer. This means applying a light application of high nitrogen fertilizer like 16-16-16 or 20-20-20 once a year in the spring just after new growth starts is enough.

Bottle Tree? Kurrajong? Which is it?

            I thought I would talk about “Bottle trees”. The reason for that? I get so many darned questions about them from readers. I get more questions from confused readers about this tree than any other landscape tree. These aren’t usually good questions; they are problem questions. All these problem questions makes you wonder if they should be planted in our warm desert at all! They should but choose a good planting location and water them carefully and not haphazardly.

The true Bottle Tree, Brachychiton ruprestis, has a bottle-shaped trunk. The Kurrajong, B. populenum, has a straigter trunk and is oftentimes called "Bottle tree" in the US. (Picture sent by reader in Australia where they are native)

What you are buying from the nursery (Brachychiton populneum) is not really a “Bottle tree” at all. The correct name is “Kurrajong”. The true bottle tree (B. ruprestis) is very different from the nursery version because its trunk is truly shaped like a bottle! It’s a beautiful oddity in the landscape. But the true Kurrajong hybridizes very easily with other types of so-called “Bottle trees”. The growers propagate “Bottle trees” from seed. Seed results from a cross between “mama” and “papa”. Unless the growers are knowledgeable, who knows what you are getting?

The Kurrajong, (B. populneum) which we here in the US oftentimes mistakenly call a Bottle tree, does not nearly have the trunk taper of  B, ruprestis. Picture sent by reader in US.

 The number one questions I get is about watering. They grow primarily in the dry interior of Australia. They are not a “swamp tree” and they are not a cactus but something in between. When you water them, think of them more like watering a palm tree (e.g., date palm) or even asparagus; they like to have their “toes” constantly in water but without the soil around them continuously wet or they will die.

Be very careful of overwatering Bottle trees, any of them. It is a delicate balancing act of giving them enough water vs watering too often when planted near or in a lawn.,

Leaf drop can be normal. It frequently will drop leaves just before  or if it’s not getting enough water (that does not mean water it more often!)

The horizontal branching and thin bark of the so-called Bottle tree can lead to sunburn if the canopy begins to thin due to leaf drop.

Plant in the spring, not during the hot summer months. Unlike palm trees, they don’t grow well after planting during the heat. Yes, they should be watered more often after first planting; maybe twice a week in the spring or fall rather than once a week. But after one growing season, apply a lot of water to a large area under its canopy but water less often. This means either apply the water slowly as in drip irrigation or build a mound or moat around the tree to hold the water so that it sinks in the ground. Applying a lot of water at once uses the same amount because “little sips are combined into one big gulp”.

Leaf scorch followed by leaf drop can occur because of watering too often or not enough water. Seldom is it from giving the tree too much water at one time unless the soil has poor drainage. Poor shade from the canopy can lead to sunburn of thin-barked limbs, particularly horizontal limbs.

The second problem I hear about from readers is sunburn or sun scorch on their primarily horizontal limbs. Sunburn on the limbs is for two reasons; the first is because this tree has very thin bark easily sunburned by intense sunlight and the second reason is due to where it’s planted. Never plant this tree in the hottest locations. It’s not a mesquite, Cordia or sweet Acacia.

Sunday, December 20, 2020

When to Prune Wisteria Depends

Q. I read your blog on pruning flowering shrubs but want to know if this information also pertains to wisteria vines? I’ve read that flowering occurs on new growth, so I am not sure about trimming it.

A. In my blog I was telling people to differentiate between plants that flower early in the spring versus those that flower later in the spring. Bottom line, always prune flowering trees and shrubs any time after they finish flowering if flowering is important to you.

Let me first give you a textbook answer. Wisteria falls into two major groups; the Asian varieties and the western varieties. The Asian varieties of wisteria flower on last year's growth (early spring flowers) while the American or western varieties flower on current season growth (late spring or summer flowering).

Something interesting about wisteria is the amount of time the plant needs to begin flowering. It's usually quite a while. Some people say 10 years to initiate flowering, others say 15 years and I have even seen some people say 20 years! That's actually quite old for a woody plant to start flowering. Typically unimproved woody plants begin flowering in about 6 to 8 years. 

Plant breeding and producing hybrids that flower earlier can address this problem. When you're pruning try to leave as much older and larger wood as possible. Prune its structure the way you want it as early as possible. A few things that can affect how soon or at what age the plant begins flowering can be removing too much larger wood, using a lot of high nitrogen fertilizers, how much shade it's growing in to name a few. It will flower when it's good and ready to flower. Just remember prune after it finishes flowering and you won't go wrong. Fertilize once a year in the very early spring with a “rose fertilizer” and not a “lawn fertilizer” or apply compost in the early spring.

Friday, December 18, 2020

Fig with Yellow Leaves

Q. I am reaching out to you to see if you could offer some advice on my established fig tree. I noticed that some of the leaves have turned yellow with browning at the end and are drying off. The tree seemed to be healthy up until the last couple of weeks. The fruit seems to be in good shape. 

 A. The fig tree appears to be okay except for a few yellow leaves. The picture you sent shows the yellow leaves in the shade or interior of the tree. That could be normal if the leaves are not getting enough sunlight they will turn yellow and drop. The most important thing is the growth of the tree and fruit production. You haven't mentioned it's growth but the fruit production seems to be good from what I understand, another indicator that the tree is healthy. There doesn't appear to be a problem except the yellow leaves in the shade in the center of the tree. For those reasons I would tell you that there isn't a problem.

I would suggest however that you keep the grass away from the base of the tree two or three feet. Dig out the grass from this area and cover the soil with wood chips. Rock would not be a good idea there. Do not plant annual flowers in that area but you could put a circle of edging around the tree to contain the mulch. I would not plant anything in the mulch area but keep it free of weeds. The fig tree will get plenty of water and fertilizer because of the lawn. 

It will not need anything extra. Make sure that the lawn is not getting so much water that it harms the tree.

Wednesday, December 9, 2020

How to Grow Roses in the Desert

 Growing roses in the desert is not as hard as one might think. It follows alot of the same principles of growing other mesic plants. 

Thursday, December 3, 2020

Landscape Fabric or Deeper Rock Mulch?


Q. About a year ago your newspaper column had a clip about stopping annual weeds & it’s in your column in the RJ this past Saturday. I had my yard re-rocked & took your advice over the advice of the landscaper who wanted to put down a screen to stop weeds. I paid extra to have him put down a 3 inch layer of rocks. I believe last year you said 3 inches & this year 4. So, now I have a lot of weeds in all of the rock areas! What happened?

Black plastic mulch under a rock mulch and eventual unsightliness.

A. Great questions and I apologize for any misunderstanding I may have created. I don’t have any pictures to go on so I’m using my imagination. Let me tell you my thoughts about this.

Do you know that the time (and money) spent to control weeds beats out time (and money) spent to control insects or diseaseor both of these combined? It's true in agriculture, too. Weed control is timely and expensive.

Here plastic is applied under rock mulch bordering a lawn. The plastic is suffocating the roots of Italian cypress and causing it to yellow.

There is some research done on the use of thicker rock mulch versus using a landscape fabric (sometimes called a weed barrier and you call it a screen). There are a number of recommendations about what to do when laying down any type of much whether it is rock or wood. The information I see on using both is either from marketing and sales of landscape fabric or from landscaping companies promoting it. 

Landscape fabric starting to poke its head out from under rock mulch in a couple of years.

Using landscape fabric under rock or woodchip mulch looks good in the beginning.

Pro landscape fabrics

The Spruce - How to install landscape fabric

Bob Villa - Landscape Fabric 101

There are some sites that are against its use. This can be from informational sites or landscapers. Its not a "magic bullet" when it comes to controlling landscape weeds.

Con landscape fabrics

Plenty of contradictory information out there and I think the main reason for using landscape fabrics AND mulch is hope. This includes landscapers as well.

Black plastic under rock mulch and planting.

First of all, don’t ever expect total weed control from anything whether it’s by mulch, a weed fabric or both. Wherever water is applied there will be weed growth. The most common places whether there is fabric applied are not is where the drip irrigation is applied. Weed barriers do nothing to prevent bermudagrass, nutgrass and many other weeds from growing

Whenever installing mulch, whichever method you use, take the time to kill weeds first before using landscape fabric or not.

Spray marker (paint) is used to mark where weed control spray is applied to a landscape to reduce spraying weeds twice.

Origin of Landscape Fabrics

Weed control barriers had their start in commercial agriculture. It was then adopted to landscapes.

Here black plastic mulch is used as a temporary mulch for weed control and warming the soil early for lettuce production in Kosovo. Straw is used between the beds as a temporary mulch.

The most effective depth for rock to cover a surface is at least 2 inches deep. Nothing is gained by having the rock deeper than four inches. The problem in making a rock mulch two inches deep. evenly, is it takes precision. Higher areas are one inch deep and low spots are three inches deep. The best choice is probably three inch depth but certainly not more than four! That's a waste of money.

Best depth for rock mulch

Hence, landscape fabrics are not recommended for weed control practices in landscape planting beds. 

Non-chemical Weed Control Strategies for Nurseries and Landscapes: Part I

Reason for Justifying Landscape Fabric

A reason for applying landscape fabric is weed control. One reason for applying a mulch is weed control. They are supposed to do the same thing. Why apply two things for the same reason? 

Applying rock mulch is a permanent layer. Landscape fabrics or weed barriers are temporary weed barriers. You are applying a temporary weed control barrier under a permanent layer. Do you see the problem that will arise if the temporary barrier fails? This doesn’t make sense to me. Using two things for the same purpose? And applying something temporary under something permanent?

What to do? 

If you have it under rock or wood mulch then it is there. Nothing you can do about it but it will be a big job if it has to be removed because of unsightliness. Hopefully it is not a solid sheet of plastic but a fabric that allows air and water to plant roots. That's better but it can still be unsightly over time.

Hand weeding. Most, probably about 90% of the weeds that you see at first will be annual. They can be easily removed with some hand labor and a hoe before they flower. Another option (one that I use with rock mulch) is a fire weeder like Red Dragon and propane. Make sure your municipal ordinances allow its use first.

There are weed control chemicals you can use to control weeds around your landscape plants without hurting them. Try applying fusilade weed control products for grass control growing in non grassy landscape plants if bermudagrass is the problem. Look for fusilade (fluazifop-p-butyl) to be listed in the active ingredients on the label. In some cases the product is simply called Fusilade. (I agree its a lousy name to remember). 

Permanent Weed Control

Permanent control of weeds is impossible but you can reduce the amount of time you spend weeding. Persistence. 

1. Never let weeds flower. This makes seed. "One year weeds, seven years of weeding." (old gardening adage). Remove them before that happens.

2. Remove weeds when you first see them. It will begin starving your worst weed problems out and you will see a reduction in your efforts the first months of your efforts! If you do this, the amount of weeding time spent on your property will become less. It will never be nothing, but it will be less.

Wednesday, December 2, 2020

Bottle Tree, Leaf Drop and Sun Damage

Bottle trees (Brachychiton populneus and locally called Kurrajong) are Australian native trees found in the northern tropical and subtropical climates there. They are classified as “drought deciduous”. Drought deciduous just means they start dropping leaves when the soil gets dry from September through December every year. For B. populneus the swollen roots are thought to store water for dry periods.

The other common Bottle Tree, (Brachychiton rupestis), does this as well and has a trunk with more of the traditional "bottle" shape. Both grow too tall and large for most home landscapes. They can be grown in lawns if not overwatered and you make sure the soil will drain fast. If these trees are watered too often or the soil does not drain well, the roots of the trees can suffocate and the trees die.

Bottle tree with horizontal limbs and thin bark gets sun damage and can drop its leaves if the damage is severe. This tree has thin bark that should be protected from intense sunlight and vandals.

They are thought of as "desert trees" but they aren't. The intense sunlight of the desert can burn their horizontal limbs and, if enough damage is done by the sun, the leaves will drop. 

Use Florel to Eliminate Fruit You Dont Want

Q. I have a 25-year-old fruitless cherry plum tree in my backyard. It is a beautiful tree, and has grown wonderfully through the years, however it has not been fruitless.  Some years have had more fruit than others, but the last few years it has been covered, with tons of fruit, making a real mess and attracting ants and rats. I was told that there is a spray that will stop it from bearing fruit. I found something called Florel, which you apparently spray on with a hose, at the perfect time between mid and full bloom in the spring. Will this work? Will it hurt bees?

This is a cherry plum called 'Sprite' , a Myrobalan plum used for fruit production. The fruit has a very high sugar content but very sour. Some types of Myrobalan plums are used as ornamentals.

A. You did some good investigating. It must be applied when it is flowering. It is safe to use around honeybees and other pollinators that might be present during the flowering time. 

For any of these "fruit eliminator sprays" it is important that the flowers are open so the spray can reach inside the open flowers and cause the ovary to abort. 

This is a fruit eliminator product, Florel, that can be used as a spray to eliminate fruit and seed of plants. The spray will not hurt bees.

Yes, Florel will work. It is best to spray when the flowers are starting to open (20% of the flowers are open) and repeat the spray when the first flowers that open are shedding their petals (80% of the flowers are open). Flowering can take two to three weeks for all of the flowers finish. The first flowers to open are those in the warmest parts of the tree (usually south, west and tops of trees) and the last to open are on the north side and those in the shade. Follow the label directions for mixing the spray with water. It won’t get all the fruit 100% but most of it. 

It is sometimes called flowering plum and it is a fruit tree. It has been selected as an ornamental because of its beauty. In the fruit tree industry it is sometimes used as a rootstock for fruiting plums and peaches and called Myrobalan plum or just plain old Myro. The fruit has wonderful flavor, very tart but full of sugar and makes a wonderful jam or jelly. 

Choosing the Right Vegetable Varieties are Important and Other Tidbits

Q. Can you also guide regarding quality of seeds and plants and recommendation for places where to get them from? Any guidance how I can improve my crop for next season?

A. Use tried and true vegetable varieties that have performed well in desert locations in the past. Make sure your vegetable seed and transplants are in good shape at the outset. Avoid purchasing seed from open locations unprotected from the elements. Dont buy transplants that appear sickly or have a problem. You are not a plant "rescuer" when it comes to problem plants. They wont perform very well. Usually the east side of walls or buildings in full sun give the best protection from late afternoon damage from sun and heat.

I get emails from newcomers to vegetable growing in the desert that try vegetable varieties with marketing claims of "amazing results" from newer varieties. Introduce newer untested varieties in small numbers and notice which do well. 

Some suggested varieties to start with include:

Vegetable Varieties

Asparagus - UC 151

Beets - Detroit Dark Red

Bush Beans - Contender

Broccoli - Packman

Cantalope - Hales Best

Carrots - Chantenay

Cauliflower - Snowball

Cumber - Straight Eight

Eggplant - Thai Long Purple

Garlic - California Early

Hot Pepper - Jalapeno

Kale - Russian Red

Lettuce - Red Sail

Onion - Yellow Granex

Peas - Knight, Cascadia

Sweet Corn - Sweet Rhythm

Sweet Pepper - Red Beauty

Potato - Red Pontiac

Radish - Cherry Belle, French Breakfast

Spinach - Melody

Tomato - Sweet 100, Roma

Watermelon - Bush Sugar Baby

Zucchini - Black Beauty


Desert climates can be finicky. High and sometimes erratic temperatures can be a problem along with wind and low humidity. Probably the most overlooked climate variable that will improve production and vegetable quality the fastest is controlling the wind. 

Did you know the best production occurs just downwind of a windbreak? They slow wind speed down considerably to a distance of about five times its height. 

Four foot tall chain link fence with PVC slats work well if installed downwind of the growing area's prevailing wind and doesn't require much maintenance or any water! 

Windbreaks made of chainlink and PVC slats slow the wind enough to qualify as a nonliving and waterless windbreak in desert climates.

Grow in Containers
Growing vegetables in containers makes it easier when there is a problem.

Five gallon containers and larger give the plants enough soil volume to hold water in the soil for at least one day during the summer. When you want to increase your growing area try containers first. They are best located on the east side of a wall or building and the container shaded from the hot sun by the raised bed, other plants, or double potted. 

No crop rotation is necessary. Just use the soil from the container for a different crop or cropping season and reuse the soil somewhere else and clean the container, if you use it again, when it gets "worn out", full of diseases like Verticillium or nematodes.

Monday, November 30, 2020

Conks Can Tell You Disease Severity

 Q. A friend has a beautiful, large, old (and productive) fig tree on a property she owns in an older neighborhood. She just observed for the first time large conks. Is there anything that can be done to save the old guy? She loves the tree and is pretty devastated, and is willing to invest to save it if possible. She would definitely have you out to consult if that could be productive. Thank you, and I have been loving your blog for years!

Conks, or bracket fungi, can be diagnostic on trees as to which disease is present and how aggressive it might be.

A. Nice pictures. My presence there wont help her or the tree I think. It is possible this "rotting disease" was brought to your tree on dirty equipment. Your decision to remove the tree is probably necessary at some time. When, I am not sure. If the tree develops weaknesses that could lead to damage or other safety issues, it is time for pruning or removal.

The conks are because of some internal rotting. The color, shape and size of the conks may be an indicator of what disease it has and how aggressive it is. To my knowledge, there is no armillaria root rot locally. To me it looks more like oyster mushroom type of internal wood decay.  Presence of conks low on the tree can mean the rotting is in the roots or crown of the tree. In this case they seem to be higher on the trunk. Try identifying which disease it is by the conk.

Figs regrow very easily from new suckers coming from the base if it has to be cut down. The internal rot CAN be an indicator of a problem and how serious it is. If you an invite an arborist to look at it, of course they will recommend removal. If the tree looks otherwise healthy, then I would knock them off if not wanted and watch the tree for safety weaknesses. It would be a loss to lose fruit but it could be fruiting again in a fairly short time after cutting back.

Make sure any pruning is done using sanitized equipment. Eventually, most likely, the tree will have to be removed. How soon you have to do that depends on how aggressive the disease is. (think cancer, some are more aggressive than others). Maybe removal as soon as a few months to a few years.

Thursday, November 26, 2020

Drought Can Substitute for Winter Cold in Asparagus

Q. I am trying to figure out when asparagus goes dormant in the desert. I have been doing some research, but I can’t find information about how to handle the dormancy period in the desert. Any ideas?

This is what you hope will happen in the winter to asparagus. In warmer climates it stays green. Turn off the water to force the plant to go dormant.

A. The usual information about asparagus says it turns brown, or goes dormant, as weather gets cold. That’s true in Michigan or Washington state. Sometimes asparagus grown in warm deserts doesn’t turn brown. It might stay green all winter long.

            Wait for the coldest part of the winter, cut it down like it was brown and turn off the irrigation. In about a month, irrigate and fertilize again to push a new crop of spears. For some plants, drought can sometimes substitute for the dormancy of winter cold.

            Not irrigating can “trick” the plant into “thinking” it just got through its dormant period. In the tropics, we let asparagus “dry out” for a month during the dry season and then start up the irrigation again. Cut it back during the coldest month, turn off the water until the soil dries, put manure, compost or fertilizer on top of the soil and then start watering again. 

When to Harvest Pistachios

Q. When should I harvest pistachio nuts from my five-year-old tree? In October the nuts were yellowish green with a red blush covering them.

The red blush on the nuts means they are close. Harvest after the "meat" has filled the kernel and start to split open.

A. The red blush is an indicator that your harvest season has arrived or perhaps even late. It’s better to look at the number of split nuts on the tree. The general time for harvesting may start as  late as late August or early September and extend through the middle or even end of October.

The nut will start to split when its ready to harvest. Turning red may be a bit late.

            The time to harvest is when the nut inside the husk fills the shell and can be removed. Commercial growers look at the number of split nuts on the tree and whether it might rain or not. Rain will mold pistachio nuts if they are split open. Pistachios are grown in arid or desert parts of the world where, like dates, rain is considered a foe. When harvest time is near nothing beats taking a few nuts off the tree and see if the “meat” is plump and separates easily from the shell.

In some parts of the world there is enough rainfall to grow "wild" pistachios which means they are grown, usually on government land, without supplemental irrigation.

            Drying the nuts off the tree enhances flavor, causes more of the nuts to open and the “meat” to separate further from the shell. If rain is predicted soon, harvest them before they mold on the tree.