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Sunday, September 29, 2019

Pear Fruit Hard as Rocks

Q. We have a mature pear tree standing about 14' tall that produces about 100 pears each year. These pears are always rock hard when harvested regardless of how long we leave them on the tree. We have attempted ripening them indoors, in brown bags, all to no avail.

A. Do you know what kind of pear it is? There are two groups of pears; the European and Asian pears. The Asian pears are normally round or roundish and crunchy, much like a crisp apple. They are not rock hard, but they aren’t soft, either. They are “crunchy” in texture.
Most people are familiar with Bartlett pear, a European dessert pear that is picked hard but ripens and softens after harvest. All pears pictured were grown by me in the Mojave Desert.

            Most of the European pears are dessert pears, but a few are cooking pears. The dessert pears will soften after harvesting but the cooking pears do not. They stay firm, some might say “rock hard” when compared to dessert pear like a fully ripe Bartlett. Some of the European pears used fresh (aka dessert pear) are Bartlett, Comice, d’Anjou, Bosc and Seckel. The stores in the US carry a lot of Bartlett but there are some excellent other dessert pears out there to try.
Comice pear, a European dessert pear, also does well in the Mojave Desert.

            Most dessert pears are picked when still hard but after the background color of the fruit has begun to lighten. This is true of Bartlett because its flesh will have a “buttery” texture when picked before they are fully mature and allowed to ripen at room temperature for three or four days.

Sensation Red Bartlett, another dessert pear, also does well here.

            I'm thinking yours is a European type cooking pear. A popular variety is Kieffer. They don’t soften much at all when ripe because they are used for cooking and making pear sauce, compote, jams, jellies, pickling and used in stuffing. 

Kieffer pear is a European pear but it is a cooking pear.

They are called cooking pears because their flesh stays firm after cooking. They can be left on the tree longer because they stay very firm when ripe. If I am right, there is nothing you can do to soften them and you either enjoy them for their cooking attributes or replace the tree.

Canary Island Date Palm with Yellow Fronds in Need of Water?

Q. This tree in my front yard is turning yellow. It is 20 years old. Is it because of lack of water? Should I have it trimmed?

This is the canary island date palm talked about. Notice the lower fronds scorching on the edges and turning yellow. Water could be an issue.

Lack of water can have two meanings. 

Not enough water applied or not watered often enough. Sometimes it can be both…too little water applied and the water that is applied is not applied often enough. 

Hard to judge but my guess is that water may be part of the problem. When water is applied to palms, a lot should be applied all at once and then hold off on the next watering for about the same time as other nondesert trees, like fruit trees, need water. For date palms in Las Vegas this is about one week, maybe twice a week at the most in the middle of summer.

See that cluster of new growth going straight up in the center top? Good sign. It had enough water to push spring growth. But what about summer growth?
The browning on leaves seen in your pictures is on older leaves at the bottom. That is normal for it to happen that way. It is NOT normal if leaf fronds are turning brown along the edges on newer fronds higher up. 
The palm to the right is getting water. The palm on the left is not. Look at the grass at the base.

Palm Drought

Water should be applied to a distance of about three to four feet from the trunk all around the tree. In many soils about two inches of water in the basin around the tree is enough to get it down to about 24 inches. This would be about 50 gallons. So the palm tree roots have to have access to about 50 gallons of water at least once a week to 100 gallons if it is watered twice a week in summer. But the important part is giving the soil a chance to drain and start to dry out after an irrigation.

This is date palm, not canary island date palm, but the roots will be similar. This date palm was removed from the farm, harvested, so the roots are cut.
It is pushing new growth from the center so that tells me If underwatering is severe the fronds will be smaller and scorched. From the picture
Palms pruned with enough canopy remaining to provide some protection to the central bud.

As far as pruning, remove the lower fronds so that the remaining fronds are in a half circle

Saturday, September 28, 2019

Pruning Determinate Tomatoes in the Fall

Q. I know Roma tomato plants are determinate in their growth but if I keep them healthy will they set a fall crop for me?

A. All I can tell you is what I think will happen if it is a determinate tomato and how to prune it for fall production. There are a lot of unknowns involved but this should give you the best chance.

Roma Confusion

            Roma tomatoes are a certain type of tomato good for making tomato paste because they dont have a lot of water inside the fruit. So sometimes Romas are mixed with paste tomatoes and plum tomatoes and called paste types. Yes, Roma is determinate but paste types are predominantly indeterminate. So check what you got.

Determinate Vs Indeterminate

Determinate tomatoes are plants that are bush-like and produce fruit over a short time so it’s easier to pick. Indeterminate tomato plants grow as tomato “vines” and produce fruit spread out along these vines over a longer time. So-called Roma tomatoes are considered paste or plum tomatoes and many of these types can be either determinate or indeterminate. It’s good to know which you are buying for proper spacing and management.

Fall Pruning

            All plants need new growth to set flowers and fruit. For Fall production we want to stimulate new growth when air temperatures are entering the mid 90s. While indeterminate tomatoes can be cut back a lot in the Fall because they are so long, determinate types are cut back less due to their smaller plant size. Prune the plant back enough to provide for new growth but not enough to open the plant canopy for sunburn. Follow this pruning with water and fertilizer.

Friday, September 27, 2019

Sunburn, Insect Damage and Pruning Desert Museum Palo Verde

Q. I had my yard re-landscaped in June and with it I planted a Desert Museum Palo Verde. After planting, I pruned it and maybe removed too much which caused some sun damage. My great aunt used a lime and water "paint" on her trees to repel critters and I’m wondering if this might help.

A. The time of year it was planted probably had something to do with the damage you’re seeing. The lime and water paint was used in the past mostly to reduce sunburn from intense sunlight. The reduced damage from painting the trunk and limbs attracted fewer insect problems.

Fruit trees with trunks painted in Afghanistan. This was probably done by someone from an NGO and not done by locals for insect  and sunburn control in Balkh Province.
lime and water concoction

But painting trees with this concoction was also used to make them look prettier. It’s still done for ornamental purposes in some countries. Now we paint the trunk and larger limbs of fruit trees with dilute white latex paint mostly to reduce damage from boring insects attracted by injury from intense sunlight. That’s its primary purpose.

Plant at the Right Time of Year

            First off, planting trees and shrubs in the spring or fall months leads to more success and less damage than planting during the summer months. Palo Verde, like most landscape plants, should be planted in late January or February or late September and October for best success. Those spring and fall months are more forgiving than planting during the heat of the summer.

Transplant Shock

            Secondly transplant shock, or the “interruption in growth” of plants when moved from a container into the landscape, is more dramatic during the heat of the summer than during the cool spring and fall months. Transplant shock that time of year varies from almost nonexistent to severe branch dieback depending on the care given when planted.

Dig the hole and planting depth

            Dig the planting hole three times the diameter of the container and make sure plants go into a wet planting hole as quickly and carefully as possible. Never plant into a dry hole even if you add water immediately after planting. Damage from planting that time of year during the summer in coastal California might be minor but not in the Mojave Desert.
            Make sure plants are planted at container depth and, after planting, have not sunk deeply into soft, wet soil. This can be difficult to detect after planting and is a major cause for plants that struggle and eventually die after planting.

Water Deep and Not Often

            Water this tree under the canopy with enough water to wet roots 24 inches deep. Irrigate again to keep the soil moist at this depth, but not wet. Irrigating frequently and deep enough to keep soils moist will cause your tree to stay full, grow quickly and recover from sun damage. When it gets larger, reduce how often the tree is watered but not the volume of water applied.

Papaya Seed for Sprouts

Q. There are lots of black seeds when you cut open a papaya fruit. Can the green sprouts from these seeds be eaten and added to a salad? I don't want to grow a tall papaya tree in my condo.

A. Since the fruit produced by this tree is not important to you, the seeds can be collected, germinated and used for “sprouts”. Not many people are using these seeds for sprouting because the white latex sap of many plants is oftentimes a warning sign parts of it may be poisonous.

Im on our farm in the Philippines now so I went out and nicked this young papaya with my fingernail so you could see the latex

            Papaya sap contains a white latex thought to be important in reducing its pest problems. This sap however is used in pharmaceuticals and meat tenderizers because it contains an enzyme called papain. 

The same papain is used to speed up skin and muscle repair from sports injuries like cuts and abrasions, “leaky gut” syndrome, and implicated as useful in treatment of shingles, hay fever and minor aches and pains. Not much is known about eating papaya sprouts. Much more is known about the papain derived from the fruit or leaves.

Its also known in local folklore to reduce sex drive. Maybe that's why its nicknamed the fruit of priests. Back in 1993 when I first went to the Philippines the locals in small villages on Palawan were pleased to see me eat alot of it and I didn't know why. I was single at the time.

Good Fescue Grass Seed for the Desert

Q. Can you recommend a good fescue grass seed for starting a lawn? I did not have great success with a local brand that said it was made for our desert climate.  

A. Most of the lawns planted in our desert climate are a blend of at least three different kinds of tall fescue. This can be read on the grass seed label. Personally, I would stay away from grass seed mixtures that contain annual rye grass, bluegrass or perennial ryegrass combined with tall fescue.
This is NOT a good tall fescue grass seed for home lawns. Great for parks but not home lawns due to its coarse texture. K31 or Kentucky 31 is a great highway grass...looks good at 50 mph

With grass seed, you get what you pay for. Most of the best grass seed blends are also the most expensive. Read the label. Buy grass seed that has at least three different types of tall fescue listed on the label. Stay away from K 31 a.k.a. Kentucky 31 tall fescue grass seed for home lawns. It’s great for parks and it’s cheap but mostly because it is durable and can handle our heat.

a hot cup of coffee is really hot and will damage grass but continual hot temps in hot climates can also be damaging. Las Vegas is in the transition zone for grass...grows all grasses poorly.

            Make sure the problem you had did not result from how it was planted or the irrigation system. Check the irrigation system before you plant and make sure it’s operating properly. The water from the sprinklers should be thrown far enough so that it reaches neighboring sprinkler heads. This is called “head-to-head coverage”.
            A seedbed needs to be prepared for grass seed at least 8 inches deep. This soil should be “firmed” enough so that when you walk on it your shoes don’t sink more than half an inch into the prepared and firmed soil. Proper soil preparation, not too hard and not too soft, is where most people fail.
            A starter fertilizer and grass seed mixture is applied to the surface of the soil with the grass seed applied at a rate of 10 to 12 pounds per thousand square feet of lawn area. Apply a very fine mulch on top of the seed no more than 1/8 inch deep. This can be steer manure or fine compost.
            Water long enough until water begins to “puddle” in areas. This tells you the maximum number of minutes you can irrigate until seed starts showing. Water twice a day at this stage; once a day when you start seeing grass. Increase the amount of minutes and decrease the frequency of application until you find that “sweet spot” to you are growing grass roots as deeply as you can.

Thursday, September 26, 2019

Guidance for Pruning Fruit Trees

Q. I need guidance on when and how to prune my fruit trees that are 3 to 5 years old. All of them have been producing fruit in the last couple of years. This includes an orange and a Meyer lemon along with a Blenheim apricot and a dwarf peach tree. All I have done in the past is basically ‘shape’ the trees; keep the height manageable and remove dead branches. 

A. Look for my Classes

I have fruit tree pruning classes posted for next January on Eventbrite. Consider signing up for one of these offered on a Saturday morning for some hands-on training with real fruit trees. These classes can answer specific questions you might have.

Lite Pruning Anytime

            Light pruning with a hand shears, removing wood that is less than half inch in diameter, can be done anytime of the year as long as it’s not overdone and opens the canopy too much. Pruning out too much allows for sunburn and borer problems to get hold in the trees. Make sure your hand shears are sharp and sanitized before you start cutting away.
            Major pruning is done from December to January, the winter months, in all deciduous fruit trees, waiting until leaf drop. With citrus, however, very little pruning is needed after you establish its structure early in its life. But when pruning is done, it’s performed soon after the fruit is harvested.

Control height

This is done to make it easier to pick and spray the trees when there are pest problems. The maximum height should similar to distances between trees. Having trees too close together, which creates crowding when they get older, forces fruit production towards the top of the trees.

Start on your knees

I find it easier to prune fruit trees working from the bottom and progressing towards the top. Remove entire limbs from the trunk to about knee height. The lowest limbs should support fruit easily harvested but the lowest fruit should not touch the ground when it’s ready to harvest.
            Remove most of the wood by pruning from the trunk and major limbs. Most pruning cuts remove entire branches. These are called “thinning cuts”. It orients major limbs so they emerge from the tree in different directions like spokes on a wheel. Most growth growing straight up or straight down should be removed. It’s not productive.

Fixing Crossed Branches, Broken Branches

            Once the overall structure of citrus trees is established, very little pruning is done. Focus on removing a branch that crosses another, sucker growth from the base of the tree and limbs that “shoot for the sky” and eliminate a branch interfering with another.
            Once the form of an apricot tree is established, only about 10% of its new growth is removed each year. I have had apricot trees that required no pruning. Much of that depends on the variety and its rootstock. Control its height if it’s too tall and get rid of any strong growth going up or down.

Genetic Dwarf Peach

            True genetic dwarf peach is pruned differently than a “normal” peach. Usually controlling height is not a problem. If the tree is overgrown, it’s canopy is thinned out so that speckled sunlight can penetrate to the interior.
            Fruit production comes from flowers growing on shorter shoots at the ends of branches. This is where most of the light pruning takes place. Most short shoots that contain the flowers are removed leaving behind only one or two of these short shoots.            

Holly and Caroline Cherry Burning Up as a Screen in Full Sun

Q. I planted hollies and Carolina cherry as an evergreen visual screen between our house and our neighbor’s house. The hollies burnt to a crisp and the Carolina cherries look bad. I need evergreens that can withstand full sun all day and give me privacy. Does something like this exist?

Carolina cherry laurel with yellowing leaves when planted in full sun and in our desert soils

A. Both of these plants will grow in our climate but not in the locations and perform in our desert the way you want or for that purpose. They are not desert plants. They can handle our desert soils and climate but they must be planted in protected locations with relief from afternoon sun to thrive. That’s why they are burning up.

Carolina cherry laurel planted in rock mulch starting to yellow. If it is planted well it will take about five years before this happens in our soils and extremes.

            A privacy hedge should be evergreen and retain leaves through the winter. If it’s a warm winter, they may stay evergreen. Some evergreen plants drop their leaves in the winter and become deciduous if it gets too cold. Colder temperatures than this, they will freeze back. Accepting this should get you through most winters here without being too upset.
            Do your homework on these and shop around because not all of these will be available from local nurseries. Non-desert plants should be watered more often than true desert plants. This means they should be on the same valve as other non-desert plants.
            Some of the best reviews of these plants are from Arizona State University in the Phoenix area but Phoenix has warmer temperatures than we do. So be careful of winter freezing temperatures. In the Las Vegas Valley, aim for winter temperatures in the low 20s for long-term sustainability and expect that they may not be evergreen or may have some dieback during very cold winters.
            Here are some true desert plants you might consider for that purpose. They can handle full sun in harsh locations. They are true desert plants originating from our Southwestern deserts and include hopseed bush, Arizona rosewood, creosote bush, jojoba, yellow bells, and little leaf cordia. Even though they are desert plants, I would still amend the soil with a decent compost at the time of planting and plant them wet. Just because they are desert plants doesn’t mean they don’t like a little TLC.
            Don’t forget standard oleander. It’s not a desert plant but can handle extreme desert conditions like ours. This means they should be on the same irrigation valve with other non-desert plants.

Recently Planted African Sumac Leaf Curl

Q. I recently found your blog and wonder if you have any advice for me about an African Sumac that we planted last October. It did beautifully through the winter. About a month ago, I started noticing some leaves curling up, but staying green. Now the lower branches are drooping and over half of the leaves have curled, but stayed green. Rot? Fungus?

I did one treatment of ferti-lome around the base last week. No change.

A. Watering too often and not watering enough can give the same results so I can see how it could be either way. The only way to know for sure is know how wet the soil is when you water again and how much water you are applying.

When you water African sumac, water it with lots of water over a large area under the tree canopy and don’t water again until it is about half gone. One of the problems with tree installations by the contractors who plant for Moon Valley I have been told in the past is the size of the hole they dig for the tree and lack of amendment added to the soil when planting. This could be part of the problem for you as well.

The hole provided for the tree  should be at least three times the size of the container. If this was a 24 inch box tree then it will be a big hole that is dug. The hole does not have to be deeper than the container but three times its width. I don’t know how much amendment was added but it should be about the same volume as the soil taken from the hole.

What can you do now? Remember this in the future but there is not much you can do to a tree that was already planted. I tell people who buy trees to be planted by a contractor from Moon Valley is to pay them extra cash and have them dig the hole wider.

 Buy your own amendment like Viragrow’s compost and provide it for them instead of the bags they bring. Water the tree in the hole AS it is being planted and flood the area planted three times, once a day. Then turn it over to the drip or irrigation system but do not water daily. Provide enough water each time you irrigate to get it down to 18 inches deep.

Water the area under the canopy of the tree at least half its width. All its width is better. Use a four foot long stick of rebar to determine this by pushing it in the soil until it is difficult to push. Water again when the soil in the upper four inches is starting to dry out.

You can use a $10 moisture meter to determine this.

Water when it reads “5-6” in three locations under the tree canopy where you watered.

How and Why to Take a Leaf Tissue Nutrient Sample

A leaf tissue analysis would show that this ornamental pear is lacking iron.

Why Send a Tissue Analysis?

The purpose of submitting leaves for a leaf tissue nutrient analysis is to find out the reasons why plants might look sickly or not performing the way we would like. These types of leaf tissue analysis identify nutrients found in the leaves and help to identify which ones may be in short supply. These types of tools are used by growers to adjust which fertilizers are applied and their timing of application in efforts to boost production or performance.

A leaf tissue analysis would show this peach tree is iron deficient

What the Sample Wont Tell You

Submitting a leaf tissue sample has nothing to do with identifying an insect or disease problem, chemical poisoning problems from weed killers or other toxic chemicals. These types of problems are best handled a different way.

Baseline Sample is Needed

Submitting leaf samples from a problem plant are not enough. Leaf nutrient analysis information is needed from acceptable plants (this establishes a baseline) as well as the problem plant. It's best these plants are genetically close to each other (the same variety or cultivar is best), they are approximately the same age, the leaf samples taken from the same locations and similar times of year. 

even though it looks like it might be nutritional, its not. Leaf tissue analysis wont show a disease problem developing like this

Sometimes two samples are submitted; one from acceptable plants and another from problem plants. When historical information exists, this information can be used as the baseline for submitting leaf tissue from problem plants so always keep old leaf tissue analysis reports!

How to Take a Sample

Select a plant or group of plants showing a suspected nutritional problem.  The plants may all be in the same area or they may be scattered through the growing area. If this problem is on only one plant, sample a single plant. If the problem is on several plants, take subsamples from several plants showing the same symptoms and combine them into one sample.  

Take leaf samples at a time of year used to establish historical baseline information. For example, if the baseline information you are using were from plants sampled in the spring of the year, take samples in the spring. If baseline information was in Midsummer, take samples in Midsummer. In some cases, a new baseline may be needed. If submitting one sample from problem plants and another from acceptable plants to establish a baseline, then these are taken on the same date.

Take leaf samples from similar areas of the plant and establish where on the plant samples should be taken from. In some cases, this might be newer growth and in other cases older growth. A simple way to do this is to take leaf samples at similar distances along the stems.

Document and Label

Label these samples in a clean plastic bag using a permanent marker with a 4 letter Code name, date they were taken, and area of the plant taken from (old growth vs new growth). Place these leaf samples in a refrigerator until they are ready to be sent to the lab for analysis.

Take notes. Write what you did and how you did it in a log or notebook. Believe me, you wont remember it next year.

Contact the Laboratory

Download submission forms from the laboratories website and fill out the paperwork.  Call the laboratory and make arrangements for the shipment and any fees that must be paid ahead of time. It is important that these samples are as fresh as possible so keep them in the refrigerator until they are ready to be sent, overnight, to the laboratory. Send them to a laboratory at the beginning of the week so they're as fresh as possible.

A plant tissue analysis laboratory that I frequently use is A and L Laboratories in Modesto CA with the website http://www.al-labs-west.com/

Friday, September 13, 2019

Desert Horticulture Podcast: Fix Your Landscape

Learn some of the basics about why landscapes have problems. Sometimes its how the landscape was designed, plant selection or irrigation. Save water and money on your power bill by following taking some simple advice.

Wednesday, September 4, 2019

Fix Your Landscape Class Offered

This four week class is two hours included in each session or 8 hours total of instruction and discussion time. It is offered on Saturday mornings from 930 am until 1130 am starting in late October in North Las Vegas near Cheyenne and I-15.

What you will learn:

  • Landscape design tips that save water and energy
  • Discussion of problem areas and how to successfully correct them
  • How to establish landscape microclimates
  • Which are desert plants and which are not 
  • How to locate and plant so they don't die
  • How to use cacti and succulents in the landscape
  • Irrigation installation Do's and Dont's
  • When to irrigate and how much to apply
  • When to fertilize and with what
  • Prune like a pro
  • Insects and diseases common in the valley and how to stop them
  • Managing a landscape contractor like you know what you're doing

Cost: $100 for all four weeks

Certificates will be given to those who attend all four classes

Sign up for the class here

Growing Fruit Trees in the Desert Class Offered

This is a 4 week class on growing fruit trees in the Mojave Desert starting late October. The class will be taught in North Las Vegas near Cheyenne and I-15 on Saturday afternoons from 1 pm until 3 pm .

What you will learn:
  • fruit tree selection and where to buy them and rootstock to use
  • spacing, row or plant orientation and size control
  • planting fruit trees correctly including soil amendments
  • use of woodchip mulch vs rock and where to get it
  • critter protection of new fruit trees
  • irrigation management
  • when to fertilize, how much to use and the type of fertilizer
  • when to prune and how
  • insect pests and diseases
  • harvesting to avoid bird problems

Fruit trees this information applies to include: peach, nectarine, plum, pluot, apple, pear, Asian pear, cherry, pomegranate, persimmon, fig, jujube, and quince with some discussion about citrus included.

Cost is $100 per person

Certificates of completion will be given to those who attend all four classes.

Sign up here

Tuesday, September 3, 2019

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.

Monday, September 2, 2019

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.


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.

            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.

Monday, August 26, 2019

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Wednesday, August 21, 2019

Wednesday, August 14, 2019

Plant Acclimation Necessary for Vegetable Transplants in the Desert

Q. I had three tomato plants, all started from seed. They were all very healthy and thriving beautifully. They were planted in a grow box filled with growing media. After about 5-6 weeks the leaves started curling up on all three plants and after about 2 weeks all plants died. When I first noticed the problem, I looked it up on the internet and it informed me it was a watering problem but not to worry. I didn't worry and they all died.

A. I don’t know if you saved the seed from other tomatoes or you bought the seed and where you bought it. I also am not sure if they were grown as transplants in the home and then moved directly into the garden.

Acclimating transplants (hardening off)

 If these tomato plants were grown from seed inside the home and then moved into the garden, they need to be acclimated to the weather before planting. Inside a home or greenhouse there is protection from intense sunlight, higher humidity and very little wind.

 Acclimate your seedlings to our weather by putting them outside in light shade or the east side of a building. After two or three weeks and you see some new growth, they are ready to go into the garden. Some old-time gardeners will put a wooden shingle on the south side of the plant to give them some protection for another couple weeks.

We used to use coffee cans too. Acclamation helps plants adjust to our desert climate and weather conditions. They go through a lot of shock if planted directly into a garden or grow box from inside a home or greenhouse. Sometimes planting them directly from a protected environment into the garden will cause them to die.

The other possibility can be watering too often and poor drainage. If the soil stays too wet and the soil does not drain water easily, the roots can rot and the stem can develop collar rot. It looks like they aren't getting enough water so most people water more often. Big mistake. The soil needs more amendments and the transplants watered less often.

Roses and Intense Heat

Q.  All my roses face north, and some are against a cinder block wall. They get no shade and they really struggle with our summer heat. Most will have to be replaced. I am already looking at roses to plant for next summer. Do you know any varieties that can withstand our summers? Also, how does Crepe Myrtle handle our summer heat?

A. If your roses are on the north side of a building then they may get direct sunlight late in the afternoon because of where the sun sets in the summertime. That late afternoon direct sun can be very damaging if they have been going on the shady north side all day. Healthy plants handle heat better. Plant both in soil amended with good compost.
Roses growing in the desert should not be planted surrounded by rock.
            Somewhat tender plants to our desert climate, like roses and crape myrtle, handle the intense desert heat and sunlight if they are growing in soil amended with organics and the soil is covered with mulch that rots or decomposes. Roses and Crepe Myrtle will struggle after a few years when planted in soils covered by rock. If you want them to look good in years to come, roses and Crape Myrtle should never be surrounded by rock mulch. Ever.
            Always plant in soils that are amended with a decent soil amendment like compost. After planting, always cover the soil with mulch that rots or decomposes such as woodchips. The woodchips on top of wet soil will decompose. Fertilizing these plants appropriately keeps them healthy, the leaves green and vibrant.
            It might be a good idea to provide some shade from that intense sunlight late in the afternoon. Plant a medium-sized shrub or build a pony wall in this location to provide a less intense microclimate for their growth.
            A list of roses that perform best in desert climates can be found on the Weeks Roses website located at www.weeksroses.com in the column titled, “Roses by Climate”.

Murcott Mandarin Orange Growing Problems

Q. I have several fruit trees planted around my fire pit near a waterfall and pond.  I bought a Murcott tangerine which has not grown an inch in 2 ½ years and the tiny fruit it produces falls off by summer. All the other fruit trees are doing fine except for this tangerine.
Murcott mandarin orange from reader

A. This citrus produces fruit ready to harvest from January through March. It originated from central and southern Florida and does best in locations where freezing is rare. Any freezing temperatures during the winter and early spring may cause the fruit to be inedible. I hope it’s planted in a warm microclimate.

Same Murcott Mandarin orange. 

            Problems like these, when similar plants are growing together and one does poorly, is usually a problem with the soil or how it was planted. Possibly irrigation. During the winter carefully lift the tree from the ground by severing the roots with a sharp shovel and lifting the rootball with two shovels on opposing sides. Gently wash the soil from the roots and put the tree in a clean bucket of water, covering all the roots with fresh water.

            Re-dig the hole so that it’s five times wider than the tree roots taken from the ground. If water drainage was a problem, the tree should be planted about a foot higher than the surrounding soil. Do not use the same soil but replace it with a soil mix amended for planting.

            When planting the tree in this hole, the roots should be less than ½ inch below the finished soil surface surrounding the tree. As soil is added around the roots, add water from a hose to remove any air pockets. Do not step on the soil with your feet but use water to settle it around the roots. Remove about one third of the canopy of the tree after planting. Stake the tree so the lower trunk doesn’t move for one growing season.
            If the soil mix was made with a rich compost, no fertilizer is needed for one or two growing seasons. Otherwise, apply a fertilizer to the soil high in phosphorus when planting. Next spring place fertilizer 4 inches below the soil and about 12 inches from the trunk with a shovel and water it in.