Do You Want to DISCUSS Horticulture in the Desert? Please join.

I created a new Yahoo Group for discussing growing plants in the desert. There is alot of experience out there and recommendations should not come from one source. If you have something to share, or just want to listen in, come join our new Yahoo Group

Click here to pioneer this new discussion group

Who will be the first to post a comment to get things rolling?

Why I Dont Like to do Plant Recommendations

Q. I was wondering what shrubs you would recommend to plant this fall (here in Las Vegas)? I prefer ones that will stay green all year long.

 

A. I normally don’t recommend specific shrubs for a number of reasons; there are so many, I would have to provide a list of 25 to 50 shrubs and we would go back and forth with questions for you to answer, if I recommend them there is no guarantee you can find them here.

So I would highly recommend some trips to the nurseries, tell them what you are looking for, they will ask you a bunch of questions to narrow the choices, they will recommend five to ten they actually carry and then you can narrow it down to a few you like.

 Then, if you give me the names of the ones you like and you can find locally, I can help you with your decisions with pros and cons. Thanks.

Call Me Looney When it Comes to Drip Emitter and Drip Design

 

Q. The landscape people are into variable emitters and think I am a little looney sticking to drip emitters.  How do you determine how many gallons to give large trees -- like African sumac, bottle trees, Swan Hill olives, Yew pines and chaste trees?

A. There are three things we have to consider when watering; how much water the plant needs, how frequently it needs it and the time of day when we will apply the water. All this needs to be entered into the irrigation controller. All plants of a similar size will be watered with a similar amount of water.

Larger plants require deeper watering and more applied water

In your example, you have two different categories of trees to consider; the desert trees like bottle tree and chaste tree AND non desert type trees like the African sumac, olives and yew pines. If they are all the same size then they will get a very similar amount of water. The difference in irrigating these two types of trees is the FREQUENCY or how often they are irrigated. True desert trees can be watered less often and should be. The nondesert trees can be watered more often.

 

If watered too often, many desert trees can have problems. If the soil drains of water freely then the usual problem we see is luxurious, unrestrained growth. Have you ever had a neighbor or friend brag, "My mesquite tree last year grew 8 feet! (i.e., I must be an extremely good gardener if I can get a tree to do that!). Well, my friend, it just means it is getting alot of water. Most desert plants respond to excess water by putting on lots of growth! As these trees get larger and larger, they will demand more and more water.

 

The smaller plants are easiest to do. I like to ask people, "What size container would you use to grow that plant?" Some people can visualize this while others have a hard time at first. Just think of the plants you see at the nursery. Generally speaking, I like to make sure the plant is getting at least half of the volume of its container to a maximum equal to the size of its container. It is better to estimate too much than not enough.


Different sized nurseery containers

 

(Disclaimer: nursery containers do not hold their namesake. For instance, a five gallon container DOES NOT hold five gallons. I know its dumb, but use its namesake anyway.)

 

You will apply all of this water in one hour. So if you need to apply five gallons of water, it will need to be applied in one hour. So the total amount of water applied to the plant would be five gallons per hour.

 

Then there are the types that are variable and can be twisted open to give you more or fewer gallons per hour. You have to figure make the conversion and convert it yourself. It is not terribly hard to do, particularly in drip irrigation. Each emitter is labeled or color coded to the gallons per hour that they emit

"Flag" type drip emitter. Usually the flag allows you to turn it on or off, you can usually pull it to clean it, and the color refers to how much water it emits per hour. They are very simple to use, clean, inexpenive and accurate. I have used them in simple drip systems with no problems for over 20 years. There are also many others depending on your needs.

 

The hardest emitters to figure out are the types that can be adjusted to different amounts of water. Many of these are adjustable between 0 (shut off) to 10 gallons per hour. It seems simple. You just twist the emitter open and it delivers more gallons per hour.




I am sorry to you out there that like these emitters. I do not share the same feeling. When I see them, I just cringe. This is a variable output drip emitter that varies from "completely closed" to "I have no idea". Landscapers LOVE them. Of course! It doesnt require any knowledge and no design is needed! Wonderful option for the ignorant.

But in actuality it begins to defeat the purpose of drip emitters: precision. Also many of these variable flow emitters are not pressure compensated. If it is not pressure compensated, then opening one emitter and allowing more gallons to flow can affect the number of gallons flowing on all the other non pressure compensated emitters on the same line. This can mean you have to twist open or twist close each emitter along the same line perhaps multiple times to get the flow that seems to be appropriate.

 

Not only that but these variable output emitters frequently emit so much water so quickly at the higher settings that it results in water puddling and running off to low spots. This is exactly contrary to the reason we should use drip emitters. So you can see that I am not terribly fond of these types of emitters.

With many different types and sizes of plants along the same line the next difficulty for most people is to figure out what size (gallons per hour) to match up with each plant along the line. So this is how I do that.

 

The first thing I do is determine how many hours or minutes the valve will be left open for watering. Frequently, for drip irrigation, the shortest time you should use is one hour. "Yikes" you might say because most people want to irrigate fifteen or twenty minutes. The problem with these short irrigation times is that it may force you to use the variable output emitters. Or it results in water applied so rapidly it does not penetrate the ground and instead runs and puddles somewhere it is not supposed to go.

 

Assume a minimum of one hour for the irrigation time. In some cases you might water for two or three hours on a single line. What difference does it make? You are not standing there with a hose and it can take all night if you want it to. There is no problem watering at night with drip irrigation. Let it soak long, slowly and deeply. Try to use at least two emitters per plant in case one plugs.

 

Here is the one hour example.

• One gallon plants, give them one gallon per hour (two, half gallon per hour emitters).
• Five gallon plants, give them three to five gallons per hour (two, two gallon per hour emitters or three, one gallon per hour emitters).
• Fifteen gallon plants give them 8 to 15 gallons per hour (two, four gallon per hour emitters or two, five gallon per hour emitters or three, three gallon per hour emitters, etc.)

Distribute the emitters under the plant canopy, one foot from the plant with distribution tubing and secure them in place with rock mulch or stakes to hold them. Emitters should be above the mulch so you can check them for plugging. Plants that are spaced closely together can, and will, get water from each other.

Does this help a bit?

Slow Growth Can Be a Sign of Poor Plant Selection

Q. We notice that some of our trees don't seem to be rooting into the soil properly.  We assume it's due to improper root ball preparation or girdling roots. Our test to see if the tree has rooted after at least one growing season is to bend the tree trunk back and forth.

            If the root ball under the soil easily moves when the tree is pushed, we assume that the tree has poor or little rooting into the surrounding soil.

            We also believe it’s a permanent problem, not correctable and thus the tree needs to be replaced.  Any suggestions for making a better evaluation and discovering this potential problem before planting?

Root circling from container plant

A. Poor tree establishment due to girdling or circling roots is a major problem with many plants, not just trees. This problem can begin at a very early age, even when it is just a seedling. But if plants are grown too long in containers then the problem can become worse.

            Once roots begin growing in circles inside a container the problem can no longer be corrected, even at planting time. This problem should be identified before purchasing and the plant rejected.

Roots seen circling when pulled from container

            Generally speaking, plants which are very large compared to their container have a significant chance of having girdling roots. Buying oversized trees in containers is no bargain.

             When buying a container plant that I can lift, I will gently pull the plant a few inches out of the container and inspect the roots for circling. This includes bedding plants! Secondly, I select trees that are not oversized for their container. Here is a case where smaller plants of the same sized containers will out-perform the larger ones.

Surface roots from circling container roots. Notice how the trunk lacks "flairing" at the soil surface on one side of the tree. One way to detect these types of roots when they are present but hidden below the soil surface.

            Plants in containers should usually root, or become established, in one full growing season. Large trees, such as those planted from boxes, may take two to three seasons. Malformed, girdling roots will continue to circle in the same pattern once they are planted in the ground. Because of this, they will never grow beyond the planting hole after planting.

            In other words, they stand a good chance of never getting established. If they never grow beyond the planting hole, the tree roots will never be strong enough to support the tree when it gets bigger.

Scoring the rootball can sometimes help repair girdling roots, if they are not extensive, when planting. This NOT a substitute for good plant production practices or poor plant selection.

            A sign that a tree may have circling or girdling roots after it has been planted is stunted growth. This stunted growth can take years after planting before it appears. It is a good idea to identify trees that have this problem early in their development.

            Another indicator is the presence of girdling roots on the soil surface and a lack of trunk flaring at the soil surface but this can take years to develop.

            Your method is a good one for determining if trees have not become established after planting. Once the establishment period is over, I use the same procedure that you prescribe (bending the trunk) to determine if there are girdling roots down there or not.

            Boxed trees are replanted from containerized trees. Normally, container trees are staked as soon as they are planted in a box. However, if the container tree had girdling roots then they will continue to girdle and never establish in the box.  

            There are three other things that can cause poor rooting into the surrounding soil as well; poor hole/soil preparation, improper staking or not staking after planting and watering too close to the tree.

Pluot Can Have Sap Oozing Like Both of its Parents

Q. We planted a pluot this past spring along with four peach trees of different varieties. The pluot just started oozing sap or gumming on the lower truck. All of the trees were planted as bare root trees. The trees have a bermed area for holding water with wood chips for mulch. I am watering two to three times a week and frequently check soil moisture around the roots with a very long screw driver.

A. In peach, gumming or sap coming from the trunk or limbs, is frequently due to borers. In both plum and apricot (the parent trees of pluots) gumming can happen without borer problems. Frequently it is a sign of stress.

Sap oozing from trunk even with trunk painted

            Make sure that the trunk and limbs are in the shade of its own canopy to reduce sunburn from direct sunlight. Sunburn damage can cause this as well. Paint the trunk and limbs with diluted white latex paint to reduce sun and heat damage to these areas.

            Dilute white latex paint with an equal amount of water and either spray it or brush it on. This will reduce the surface temperature of these areas about 5 to 6 degrees. We normally do this in the winter when we don’t have to fight with the leaves and after pruning is done.

Buford Holly a Thing of the Past In Las Vegas?

Q. We have two holly trees in our front yard that are at least 40 years old.  Last summer one of the trees began to get curled leaves and this year the entire tree looks like it is dying. The trees are on the north side of our house and get sun in the morning and afternoon. We were told locally that the trees are probably dying from old age but they didn’t know the name of the tree. We had our entire front yard replaced with desert landscaping this spring but that should not have caused the problem because one of the trees began getting curled leaves last year.

Plant problem sent in by Reader

 

A. Years ago Chinese holly (Ilex cornuta) was commonly planted as a foundation plant in southern Nevada. They performed best planted on the north or east sides of a home, somewhat protected from the hot sun.

            The most commonly planted Ilex was ‘Bufordii’ or Buford Holly. You can google this name in google images and see if it matches your plant. With the onset of desert plants and desert landscaping it has pretty well been forgotten along with some other really cool plants. All the nurseries in Las Vegas carried it forty years ago and many up to about 20 years ago.

Buford Holly foliage
 http://hort.ifas.ufl.edu/treesandpowerlines/ilex_cornuta_burfordii_foliage.shtml

 

            Buford holly is fairly long-lived but I have to agree a bit that as  they age, without proper care, they will begin to decline.

Buford Holly berries (poisonous) from University of Florida website
http://hort.ifas.ufl.edu/treesandpowerlines/ilex_cornuta_burfordii_berries.shtml

            I am not sure what the problem is but since one or two limbs are dying back you will most likely see the cause by following those dead limbs back inside the plant until the dying stops. The problem should be at that spot or very close to it.

            A real guess is that it might be a wood boring insect that is common to all plants here. I rather doubt that it is a disease but it is most likely mechanical or physical damage by insects tunneling or accidental damage by a human being.

            Buford holly is a beautiful plant if it is well cared for. It will get to about six feet, taller in very protected areas. It can be grown into a small tree maybe getting as tall as 20 feet. The thick glossy leaves have spines but not nearly as spiny as English holly.

            They will produce more red berries in winter if you have a female plant and there is a male nearby. Sometimes they appear to produce these red berries with no apparent mate nearby. All hollies grow best in rich, slightly acidic soils. They would do nicely grouped with camellias and other sun-tender and acid loving plants.

From residence in East Texas
http://easttexasgardening.tamu.edu/homegardens/easttex1.html

            Remove this dead limb by cutting it just above the healthy part of the limb. Add another drip emitter or increase the amount of water that is applied and apply a fertilizer such as Miracid or a fertilizer for acid loving plants at least once a year in the spring. Do it now if it has not had any for awhile.

            Applying mulch to the base of the plants will help conserve moisture, add nutrients to the soil, make the soil more acidic, reduce weed problems and improve the general vigor of the plant. It would help to have it pruned carefully by someone who knows how to prune.

Wanted: Home Residential Landscape Sites in the Las Vegas Valley for a Research Study

I am looking for about 50 residential landscapes located in the Las Vegas Valley that would cooperate in a water use study.The study is being conducted by UNLV in cooperation with local water authorities. The study cannot offer much in return except that you might learn something about your landscape watering that you didnt know before.

This is what we are looking for:

• It must be located in the Las Vegas valley.
• Landscapes can be all desert, all turfgrass or a mixture of both.
• Landscapes should already be on some sort of irrigation controller (clock).
• The study will last about nine months.
• There will be a small modification in how your irrigation system is run that is TOTALLY reversible after the study.

If this is something that you could partner in, please contact me at Extremehort@aol.com

Thanks for considering it!

Is My Photinia Over or Under Watered?

Q. I have no idea if I am over watering or under watering. My red tip photina plants are all brown and dropping leaves left and right. My sago is turning yellow. I have a drip system and it is set for twice a day ever other day for 10 minutes. Is that enough?

Photinia growing in rock mulch

A. Usually drip irrigation is measured in gallons per hour, not in the number of minutes it was operating. Each emitter operates in a specific number of gallons, or fraction of a gallon or liters, it will deliver in one hour. 

Problem photinia

Drip irrigation does not need to come on twice a day unless the drip emitters are those emitters I don’t like very much, the kind you can twist open and get some unknown volume of water. Under the right conditions those will put out so much water that it can run all over the place. Then you might need to have it come on several times just to keep the water in one spot.

With drip irrigation you should apply all of the water it requires in one application.  If your drip irrigation is operating at the same time as your lawn is being watered then this is a big no- no. This is frequently why drip is operating in that ten to fifteen minute range. Lawns should be irrigated separately from trees and shrubs. 

In your case, If your drip system is applying 2 gallons per hour through the emitters then the plant is getting 1/3 gallon each time you water which is 2/3 gallon total every other day.  The larger the plant, the more water should be applied to it.  For a one foot tall plant try and give it about 1 gallon of water each time you irrigate.  If your plant is 2 feet tall then try giving it to a gallons of water each time you irrigate.  If plants are 5 feet tall, give them about five gallons of water at each irrigation.  This is a very rough estimate.  My sense is that you may be under irrigating.

Photinia after corrective action was taken

Photinia have another big a problem if they are growing in rock mulch.  In rock mulch, they tend to yellow and begin to scorch around five years after they have been planted.  The soil under the rock mulch has become mineralized and they can not take up enough nutrients to satisfy their needs.  You can try to supplement these mineral requirements by adding a good fertilizer once or twice a year and an iron chelate to the soil in about late January or February.  Try using a good quality fertilizer for trees and shrubs like miracle grow and add an iron chelate to the soil such as iron EDDHA.  It is hard to find and expensive but usually Plant World Nursery on Charleston boulevard carries it.

If a Sago palm is planted in a very hot location with lots of reflected light it can begin to yellow.  It can also begin to yellow if we have a very low winter temperatures.  You will see yellowing due to very cold low temperatures very early in the spring or late winter.  If it is yellowing because of a lack of iron then the iron chelate mentioned above will correct it.  If the yellowing is because of watering too often then you may correct it by correcting your irrigation and not watering twice each day but watering only once on the irrigation day but applying more water.



 

How Do You Propagate Arizona Rosewood?

Q. How difficult would it be to propagate Arizona Rosewood? And how should I prune one to shape as a multi-trunk tree, with more foliage in the 6' to 12' height zone?

Arizona rosewood as a shrub
Arizona rosewood as a tree

A. It can be propagated from cuttings and seed. The easiest is from seed.

Cuttings of Arizona Rosewood should be taken in May and treated with a rooting hormone. Expect at best about 50% of the cuttings to root.

With seed, collect seed from seed pods when the pods are fully mature. Put into the freezer in a plastic bag for about 6 to 8 weeks and sow the seed in sterilized planting mix.

 Arizona Rosewood is a slow grower. With Arizona Rosewood you would want to select four or five main stems coming from the ground or very low on the trunk. These should be going in different directions to give the plant balance.

 Remove all new or existing small growth from these four to five stems and concentrate growth in the upper canopy. Thin the growth in the canopy  to major stems growing outward and remove growth going straight up or down, growing back toward the center of the small tree or shading other growth by growing too close together.

You will get faster growth if you have fewer stems. Growth will be reduced if you have LOTS of places where growth can occur. Always keep the canopy occupying at least half of the plants height.

 As the plant gets larger let the canopy occupy 2/3 of the height of the plant and keep the trunks free of new growth as soon as you see it. You can usually pull this new growth out and will not need a pruning shears if you get it when it is young.

Tricks to Container Gardening in the Desert

Q. I was wondering if there is a trick to container gardening? I have been using potting soil, along with plant food, and my plants keep wilting. What am I doing wrong?

 

A. I am not sure what is going on in your case but container gardening can give you some flexibility in growing things but it can also be a bit trickier because of the limited soil volume, how water moves through a container soil and finding or creating the right environment.

            Start with a container that is fairly large. Small soil volumes are difficult to keep moist during our desert heat. If the soil dries out, water will flow down the inside of the container wall and not wet the soil properly. If this is unmanageable, put a smaller container inside a large one to give it some shade.

Large containers have more soil volume which holds more water and help keep the soil cooler.

            When wetting soil in a very dry container, use a wetting agent with the applied water. A tablespoon of liquid detergent in a bucket of water will work. Add the detergent after the bucket is full of water and mix it.

            Always make sure the water can drain from the container directly out of the bottom to keep salts moving through the soil and out of the container. When watering, add about 20% extra water (1/5 of the volume applied) to keep salts moving through the soil or they will build and damage the plants.

            At every planting time, replenish 1/4 to 1/3 of the soil volume with new soil. Make sure the soil is good quality. There is plenty of junk being sold locally and in bags as well.

            Shade the container (not the plant) from direct sun during the day time. You can do this by double potting it.



Houseplant moisture meter

            Use an inexpensive soil moisture meter for houseplants to give you a rough idea if the soil is wet or dry. Otherwise lift or push the container. Containers get much lighter when it is time to water.

            Fertilize lightly once every one to two months during the growing season.

            If you have trees in containers, gently lift the tree from the container every three to four years, prune the roots, replace the soil, prune the tree to reduce its size and to bring it back to scale and replant it.

Pine Needles are a Benefit to Desert Soils

Q. We have nine pine trees and they are dropping lots of needles. We have a large berm under the trees and water inside the berm twice weekly. Should the needles be removed or left in inside the berm?

A. The needles are fine. If composted, they are said to be slightly acidic and will benefit our alkaline soils. If they are left alone in the basin, they will help mulch the soil, conserve water, reduce weed emergence and benefit the soil in general.

            A lot of needles blew out of the trees during the last storm event we had.  This is a normal occurrence and nothing to worry about.

Pine needles die for lots of reasons. Sometimes it is just old age. Some pines can keep needles on limbs for five years or more. Others only about three. They stay loosely attached or caught in the limbs even though they are dead. A big wind comes and blows them out of the canopy.

            If pine trees are getting plenty of water and fertilized once a year they will have a thick, lush canopy and grow about 12 to 18 inches a year. If water is not enough, they will not grow as much and not have a dense canopy. They will survive like that but just not be as thick and lush.

            Your berms should extend three to four feet from the trunk and deep and level enough to hold about three to four inches of water. Your watering frequency sounds right. Just make sure it gets enough water each time to move into the soil two to three feet or more. In sandy soils water needs to go deeper and more often.

Cutting Tomato Plants Back Now

Q. We actually took off the last tomato early this week.  Not fully ripe, but took it inside so no bugs or others would get to it. Somewhere I remember reading that you can cut them back to 12-16" and they will grow again. 

A. You can cut them back to some side shoots now but it will open the plants to sunburn if you are not careful and the plant may die. It is possible to cut them back now while it is still hot but make your cuts so that you reduce their height and still leave plenty of side shoots.

Sunburn on tomato on fruit and leaves.

            Another possibility is for next year. Try planting some from seed in early to mid-July. Put the seed between the plants and cover the soil and seed with straw to keep it moist and hand water daily. Make sure you mix compost into the soil in the spots where you planted the seed. Soak the seed in water four to six hours before you plant it. This will speed up germination. In about late mid to late August, cut or remove your old plants and let the young ones come in for production in September through November.

            Stake or trellis the plants and thin side shoots so you have better air circulation. Reduce any winds you have on the area with wind screens or windbreaks. Make sure you have at least 6 to 8 hours of full sun, fertilize lightly every 30 days AFTER you see flowering.

African Sumac Selection Present Problems to Homeowners

Q. I have read over and over that African Sumacs are fast growers. The African Sumacs here seem to be at a stand still! I have two in my backyard since April. They are alive but the canopy and trunk just seem the same, perhaps 10% growth. The trees are sold with tall, thin trunks - like 1/2 to 3/4 " diameter, with a canopy that branches out at 8 feet. There are no branches or leaves below that. The trees are staked high and the stems are all finger diameter. Will they take off eventually?

A. Trees with a long, skinny trunks with no side branches until 8 feet are a problem. This is done at the wholesale nursery to increase their height and make it easier to ship. It is to their advantage, not to yours.

            To have strong trunks, tree trunks to be tapered from top to bottom. In other words, to have good trunk strength the trunk needs to be bigger in diameter at the bottom and get narrower up the trunk. This helps to support the canopy. If they don’t, a good wind will come along and snap the trunks.  

Trees with no taper cannot support their own canopy. Leave any growth on the trunk that develops and stake as low on the trunk as you can to allow the trunk to move. Both of these things will help develop a tapered trunk.

            Trees develop tapered trunks from two major events in their lives; trunks swaying back and forth in the wind and the presence of branches with leaves all along the trunk. Both have a great deal to do with trunk taper and consequently its strength.

            When trees are staked, trunks should be immobilized no lower than it takes to hold the tree upright and still allow some trunk movement. The stakes should be removed as soon as possible after planting; usually no longer than one full season of growth.

            Next, never, never remove branches growing along the trunk if they are smaller than pencil diameter. Once these stems reach pencil diameter or thereabouts, cut them off flush with the trunk with a clean, sanitized bypass-type pruning shears.

            Never plant in a DRY hole. Make sure the soil in the hole is wet when tree roots come in contact with it. Planting in a dry hole can set a tree back, or any plant for that matter, due to root damage.

            Sometimes people say this is “transplant shock”. Well, yes, plants do have a setback, or shock, when removed from a container and placed in the ground. This can happen for many reasons but the DEGREE of setback can be under your control.  

            Why are they growing so slow? The amount of total growth on a plant (add up all new growth above and below ground) is divided by the number of places where growth can occur. Stems in full sunlight or without competition from other branches will usually be the strongest in growth but the total growth must be divided among every place that is growing. This includes the roots and any increase in the diameter of stems and trunks.

            If you want a plant to grow faster, reduce the number of places where growth occurs. Prune out unnecessary stems so that the growth is focused on those stems where you want growth to occur.

            You may see sprouts coming out of the trunk. Leave them. Do not prune them out until they are pencil-sized or larger but leave the small ones to help build caliper or taper.

Horticulture specialist Bob Morris says you can grow anything in the desert - Las Vegas Sun News

Horticulture specialist Bob Morris says you can grow anything in the desert - Las Vegas Sun News

Please Join Discussions About Desert Horticulture

I have been impressed with discussion groups. Members can add comments and their own experiences. There are lots of you out there who could contribute and lots of us will also learn in this exchange. If you have an interest in helping our desert dwellers, new and old, and learning in the process please join me in the Yahoo Discussion Group - Desert Horticulture.

Xtremehort
aka Bob Morris

 

We had 85 people look so far, and only three people join.

 

Some Eggplant Varieties That Have Performed Well in the Hot Desert

Japanese Eggplant descriptions

Millionaire. Very popular eggplant variety. Black-purple fruit about 8 inches long is an early producer. One of the most popular Japanese eggplant hybrids sold in markets.

Senryo ni  gou. Excellent for home gardens in Japan. Glossy black oval fruits to 5 inches long and weighing about 1/4 pound. Good for pickling.

Shoya long. Purplish-black fruit up to 14 inches long and purple calyx. Early producer for stir fry, grilling and tempura.

Yasakanaga. Purple-black fruit to about 7 inches long with purple calyx. Grilling, stir fry and tempura.

 

Mizuno takumi. Popular with chefs, purplish-black oval fruit weighing about 1/2 pound. Used for cooking or pickling.  Very popular in Japan.

Kyoto egg. Supposedly heat resistant according to seed catalogs but most are good producers during the heat. Round fruit to about 3 inches in diameter. Stir fry or deep frying, grilling. Purple calyx.

Kurume long. Ten inch long black fruit with purple calyx. Produces a bit later but prolific when it starts. Open pollinated.

Konasu. Very small round dark purple fruits with purple-black calyx. Can be cooked but popular for pickling when young, stir fry and grilled in a kabob.

Kamo. Round fruit with flat bottom and purple-black skin weighing up to 1/2 pound. Very well-known eggplant in Japan.

 

Ping Tung. Chinese eggplant that is purple-black up to 18 inches long with green black calyx. Good producer.

Black Beauty. Large purple-black fruit but slow to yield and low yielding but excellent quality.

Thai Long Purple. Very long, purple black fruit with green calyx. Very good quality and good producer.

 Thai Long Green. Fruit is similar to Long Purple but green. Similar quality. Green calyx.

Thai Yellow Egg. More of a novely or decorative eggplant. Fruits are golf ball sized and lemon yellow when ready to pick.

Gardenia Problems in Desert Soils

Q. I have two gardenias in the backyard in 15 gallon ceramic pots with good drainage. One of them is doing pretty well and the other not so well. Our backyard is on the north side so both are shaded most of the day. The picture I sent to you has leaves turning yellow and then brown on the interior of the plant although the ends of the branches still have green leaves. Both plants are on drip and watered the same. I added iron on top of the soil and also Vigoro 10-8-8 plant food but it doesn't seem to be helping. The one I planted about 6 weeks ago has not done well. The other one was planted 3 months ago and is doing well with lots of flowers in May. Any suggestions for the one with the yellow leaves?



Gardenia leaves yellowing in potted gardenia. This could be salt accumulation.

A. It is tough to acidify soils here in our desert due to the alkalinity of our native soils and our water. So if you can acidify the soil as best as you can, it will help. Ways to acidify the soil include using composts, raw composts, manure products, sulfur, acids and aluminum sulfate.

My best shot at the gardenia is iron even though you added some. If you don’t use the right iron, it may not work. Use an iron chelate such as EDDHA with iron. You can pick up a one pound canister of this iron chelate locally at Plant World. I don’t know any other place it is being sold. Combine it with a soil application of your Vigoro fertilizer.

You might also consider some of the Miracid products.

Try to use fertilizers specially made for gardenias in the future if you can find one. If you can’t, use one for azaleas and rhododendrons. If you can’t find that, a third choice would be to use one for tomatoes, fruit trees or roses. Fertilize about once a month during the active growing season. These should be very light fertilizer applications.

Whenever you are watering a plant in a container, you want to add enough water so that about 20% of the water runs out the bottom. This helps keep salts leached from the soil. Our tap water coming from the Colorado River is quite salty and you need to make sure the soil stays flushed of salts coming from the water.

If you don’t, these salts will build up in the container soil and also cause exactly the problem you describe. You can’t let the soil go dry so it might be a good idea to buy one of those inexpensive soil moisture meters used for house plants which can give you a rough idea when the soil is dry and you should irrigate.

You want the soil to dry down between waterings but not too much. If it doesn’t dry down, you may develop root disease problems on camellias. If you let them get too dry, they will drop leaves and the remaining leaves will become scorched.

It is hard to judge when container soils are going dry. One way is to get an idea of its weight. You don’t have to lift it but just budging or moving it a little can give you an idea.

Fertilizer Recommendations for Grass, Trees, Shrubs for Homeowner Associations (HOA)

We need expert opinion soon about what to use as fertilizer for Greenway grass, bushes, and trees. Your advice please.

Greenway grass

Q. What is the range of N-P-K in cow manure that some landscapers use for grass?

A. It's really not fair to compare cow manure to a fertilizer because it really isn't. They are using it more as a top dressing than as a fertilizer application. Manures vary in fertilizer content but are generally about 4% nitrogen and usually low in phosphorus and potassium. You should not rely on cow manure as a fertilizer. The fertilizer should be applied separately from a cow manure. An inexpensive fertilizer for starting plants and getting root growth from seeds, seedlings or newly planted trees and shrubs is 16-20-0 or DAP (18-46-0).

Q. What inorganic fertilizer would you recommend and the amount/acre?

A. For turfgrass you should never apply more than 1 pound of nitrogen every 1000 ft.² or 43 pounds of nitrogen per acre. In my opinion, this is excessive and should be closer to 1/2 pound of nitrogen per thousand square feet or 22 pounds of nitrogen per acre. This would be for inexpensive, quick release agricultural nitrogen fertilizers. If you are applying more expensive horticultural fertilizers that contains slow release nitrogen, then you can bump it up. How much to bump it up depends on what percentage of the nitrogen is slow release in the fertilizer.   

Q. Use 10-10-10 at 500lbs/acre maybe?

A. The fertilizer you mention has 10% nitrogen. It is not a good turfgrass fertilizer but it's fine for trees and shrubs. In fact, turfgrass fertilizers are fine for trees and shrubs as well. The best turfgrass fertilizers are in the ratio of 3-1-2 or 4-1-2. An example would be 21-7-14, a 3-1-2 fertilizer. To apply 1 pound of nitrogen requires 10 pounds of fertilizer. Using your fertilizer you would apply 430 pounds of the fertilizer to get 43 pounds of applied nitrogen. Like I said, I think this is excessive and you will not see the difference once you exceed three quarters of a pound of nitrogen per thousand square feet or about 33 pounds of nitrogen per acre. In fact, if you apply 1 pound of nitrogen per thousand square feet it will push turfgrass growth quite rapidly.

Q. How many times per year and which month(s)?

A. For tall fescue turfgrass I would apply nitrogen four times a year; Labor Day, Memorial Day, Fourth of July and Thanksgiving. During the hot summer months I would always make sure you do not exceed 1/2 pound of nitrogen per thousand square feet or you could end up with some burning if people are not careful. If you are using mulching mowers you can skip the Fourth of July application. If you are using mulching mowers you should never exceed 1/2 pound of nitrogen per thousand square feet in a single application.

Q. Should a roller of punchers be used immediately after fertilizing?

A.I assume you mean aeration. Core aeration can be done any time of the year and does not really relate to a fertilizer application. The only exception might be when you are applying a high phosphorus fertilizer.                           

Q. Should organic fertilizer (cow manure) even be used to fertilize grass?

A. Cow manure is not a fertilizer.

Bushes

Q. What inorganic fertilizer (N-P-K) would you recommend and the amount/bush?

A. Turfgrass fertilizers in the ratio I mention above are good for most trees and shrubs. You would apply this fertilizer in the very early spring or late winter. The amount to apply is similar to the amount you would apply to turfgrass but is calculated under the canopy area of trees and shrubs. A small tree that occupies 100 ft.² of canopy space would get 1/10 of a pound of nitrogen. A tree that had 1000 ft.² under its canopy would get 1 pound of nitrogen. The driver of growth for trees, shrubs and turfgrass is nitrogen.

Q. Applied dry, or liquid, in the gravel around bushes?

A. Dry fertilizers are applied near the irrigation source. If trees and shrubs are irrigated by sprinklers, then you distribute the fertilizer so that the sprinklers pushed the water into the rootzone. If these are drip irrigated, it is applied in the soil next to the drip emitters and the water carries a fertilizer into the rootzone. If you are applying a liquid fertilizer to the foliage obviously you have to wait for the foliage to appear in the spring to make an application. If this is a liquid fertilizer applied to the soil and make the application close to the drip emitters within a few inches under the mulch or under the turfgrass. Never apply a fertilizer to trees and shrubs deeper than about six or 8 inches. Fertilizer spikes are convenient but expensive. Liquid applications to the foliage last about 4 to 8 weeks. Dry fertilizers applied to the soil last longer if that's important.

Q. How many times per year and which month(s)?

A. Most trees and shrubs will require a single application of a fertilizer to the soil during the months of December through about March. In a pinch you could go as late as April. Some plants tend to get yellow due to iron chlorosis or a lack of available iron. Usually a single application of an iron fertilizer that contains the chelate EDDHA is enough to keep them from yellowing. If these plants have been yellowing and are in poor condition for several years, this will probably not work in correcting a severe problem. The iron fertilizer should be applied at the same time as the other fertilizers, in early spring or late winter.

Tall trees

Q. What inorganic fertilizer (N-P-K) would you recommend and the amount/tree?

A. You can use a good turfgrass fertilizer for most tall trees and shrubs. To be effective this fertilizer should be applied close to a source of water for the trees so that it is washed into the rootzone. It should not be applied deeper than 6 to 8 inches in the soil. Other fertilizers in ratios like 1-1-1 are also okay but the high phosphorus of the middle number is really not needed unless these are flowering trees.

Q. Applied dry, or liquid, near the end of branches around trees?

A. Fertilizer is fertilizer whether it is applied dry or liquid. The amount of nitrogen applied per tree is what is critical. Liquid fertilizers applied to the foliage are short lived. Dry or liquid fertilizers applied to the soil last longer. For this reason if you feed plants through the foliage you will have to do it more often. If you feed plants through the soil as soil applications you would just do it once a year in most cases for general purpose areas. You do not have to “deep root” fertilize if it will cost more to do it.

Q. How many times per year and which month(s)?

A. Once per year is enough in the very early spring just before new growth or not long after it begins.

 

How Tall Should a Wall Be to Keep Out Rabbits?

Q. We are planning a wall to surround our yard so we can keep the rabbits out.  We live in Sun City Anthem in Henderson. We have been told that the local rabbits can jump very high, and our 3 foot wall will not work to keep them out.

A. We have both the Desert cottontail and the jackrabbit. I don’t agree with the advice you were given. Our chicken coop wire at three feet tall was very effective at keeping them out of our vegetable plots as long as they could not lift the bottom edge of it with their noses or dig a little bit and get under it.

Black-tailed Jackrabbit

            Usually animals will not jump walls if they cannot see the other side. If they can jump to the top of it and look then that is different. I have never seen rabbits do that. But check and make sure there are not gaps in the wall itself. If they can get their head through a hole, they can get the rest of their body through it as well.

Bottle Tree Dropping Leaves Could Mean Trouble

Q. My Australian bottle tree and African sumac are shedding leaves like a maple tree during fall.  However, they are also putting on new growth.  I specifically chose these trees because they remain green all year long. The bottle tree is about 20 ft. tall, on the north side of the house and gets about 20 gallons of water every day during the summer.  The sumac is on the west side and is about 12 ft. tall and gets about the same amount of water.  I’m about ready to cut them down due this leaf shedding. Were they stressed during the heat wave or what?

A. These two trees have very different watering requirements. The bottle tree is a true desert adapted tree while the African sumac is not. Their watering needs are very different for this reason.

            The bottle tree should never get daily watering. Even though the watering needs of the African sumac are more frequent, it should not get watered daily either. It is possible that these trees are dropping leaves excessively because their roots cannot “breathe” due to excessive moisture in the soil.

Bottle tree in desert landscape

            At the most, the sumac should get watered deeply twice a week right about now. The bottle tree less often than that but when it does get water it should be deeply as well.

            Evergreen trees do drop their leaves. No plant is without leaf drop. Some keep their leaves longer than others.

            Normal leaf drop time for evergreen plants is during or shortly after new growth. As they put new growth and new leaves on new branches they drop older leaves from older wood. This is normal. However, excessive leaf drop is not. This can indicate stress ranging from drought to overwatering.

            Please get on a deep and infrequent watering schedule rather than a daily one. This time of year the only things watered daily are fescue lawns, annual flower beds and vegetables. The larger the plant, generally speaking, the deeper the root system, the less frequent the watering but the amount of water applied each time is higher.

            Frequent, shallow irrigations force roots to grow shallower and decrease their tolerance to droughty conditions. Both of these trees can develop root rot from frequent watering and death. Excessive leaf drop can be a sign that this is happening.

Bottle tree in lawn

            I would begin to back off to watering every other day for right now but increase the amount you give them each time you water. Both can handle the heat but not daily watering, particularly the bottle tree.

            Make sure the applied water is distributed evenly under the canopy either by having several drip emitters under them or watering them in a basin and flooding the basin. The water should not be applied in one location under the canopy. Back off on the daily watering. I hope they are not in stages where you can keep them from getting worse.