Q. We planted a five-gallon tree three weeks ago. At first, we watered this tree every day as the nursery directed. Then we began watering it every other day but the leaves started falling off. Daytime temperatures are 80 to 85° and drop to 40° at night.    A. Leaf drop after planting falls under the general category of “transplant shock”. The plant was “traumatized”, in human terms, sometime after it was at the nursery through when it was planted.             This “trauma” can result from a lack of care in transporting the tree from the nursery to its new home, a radical change in locations such as growing under shade cloth and then plunged into full sun as well as rough handling during planting. Transplant shock when planting from nursery containers can happen for a number of reasons.             The plant went through a radical change or changes in its environment. Once adjusted to one environment, moving them to a radically different environment can cause “trauma”. It dropped its leaves in response. Plants can’t move. A reaction to trauma can be sudden leaf drop.             The tree is not dead but needs time to recover. Our immediate response to leaf drop is to give the plant more water. We think leaf drop = drought. This would be the wrong thing to do if the problem was not from a lack of water. Fruit trees frequently drop their leaves after planting if the conditions aren’t perfect. This can be for a number of reasons but there are buds on the stems and trunk that will replace the lost leaves in a short time.             When given time, “traumatized” trees produce new leaves and readjust to a new environment. New growth is better adjusted to the new environments. Be patient and don’t overreact.             The nursery was right to tell you to water it every day immediately after planting. Back off and water only when it “needs it”. Give the plant a one day “break” between waterings. Let the water drain from around the roots. Let the roots “breathe” and the plant will recover on its own.

Q. Tell me when the first frost occurs in Las Vegas? I have tomato seeds that require planting indoors 5 to 6 weeks before the first frost. Freeze damage to plants can be as early as March 15 in the Las Vegas Valley A. If I give you that date, you will start tomato seeds too late. I start tomatoes from seed right around January 1 in the Las Vegas climate. The “first frost date” in the Las Vegas Valley is considered to be March 15. Tomato seedlings grown in the greenhouse             March 15 is when, historically, there is a 10% chance frost will occur after that date. But in most years using this date is too late for calculating when to start seedlings. In some years you might put out tomato seedlings, with some protection, the middle of February. Other years it might be the first week in March. Rarely will it be the middle of March. Picture of a tomato transplant I got online but lost the source. Nice-looking transplant.             By starting tomatoes from seed on January 1 you will be ready to put tomato seedlings into protected areas outside by mid February. If you discover this date is too early, delay putting them out for one or 2 weeks or until the weather gets better.             Watch weather reports for the coming week. This gives clues whether you can put tender seedlings out early in the season or if you must wait until later.             Seedlings need to be “hardened off” 2 weeks before putting them in the garden, particularly when starting them inside or in a greenhouse. Hardening off seedlings means moving them outside into protected locations and gradually getting them adjusted to a much harsher environment. Plunge them into this harsh environment gradually.             Protect tomato new seedlings if temperatures drop into the 40s. Freezing doesn’t occur until 32°F but tender plants like tomatoes can suffer “cold damage” at temperatures in the 40s. Think about what happens when you put a banana in the refrigerator. Tomato plants are also tropical, just like bananas.

Ash decline disease hits younger ash trees if they are water stressed. Hits older ash trees for simply no reason at all Sooty canker disease in Chinaberry. It hits many different trees including Mulberry.Frequently associated with stress. The stress can come from drought.   Aleppo pine blight usually happens in the winter months and associated with a lack of water. Q. I have noticed that many trees including elm, pine, ash and mulberrry have dead and dying branches.  I am a native of Las Vegas and have never seen this before.  It is not the lack of water.  The branch suddenly dies and then eventually the whole tree in the case of one pine.  Thought it was a lightning strike but not so sure now.  I am speaking of the northwest  area  of town near Texas Station. A. There isn’t a life-threatening disease that is spreading community-wide among all of those different plant species that your mentioning. Ash trees do get a disease called ash decline that causes branch die back. I’ve mentioned that several times in my blog. It hits younger ash trees when they are water stressed. Older ash trees seem to come down with it. Mulberries seem to get hit fairly hard with a different disease called sooty canker and I’ve mentioned that in my blog. It’s often times associated with trees that are stressed.  Possible sooty canker of Mulberry Aleppo pine is hit in the winter time with a disease called Aleppo pine blight which causes tip die back and branch die back when the disease is extreme. It is usually associated with drought. And Siberian Elm, well, good riddance. It’s a horrible tree, trashy, soft wood that breaks in the wind. Not to be confused with Chinese Elm which is a beautiful large tree with very few problems.But Siberian Elm’s usual problems are related to water and dieback. Chinese elm not to be confused with Siberian Elm is a wonderful tree I think a lot of what you’re seeing is related to water. I moved here in 1984 when water was abundant, cheap and everyone watered with abundance. In the late 1980s and into the early 1990s there was a campaign in town to get rid of all the lawns.  The campaign was called “Cash for Grass” program where water utilities were offering people money if they converted their landscapes from grassy landscapes to rock landscapes. Those big trees that survived for years on water given the lawns were suddenly put on small drip emitters and surrounded by rock. 90% of the time these large trees either died or had severe setback because they were not getting enough water. You see this kind of problem less often where these large trees are growing surrounded by lawns. Now you have my $.02 worth.

Q. Just wondering if and when I should prune my Tecoma “Yellow Bells”. Yellow Bells Tecoma stans A. Yellow Bells or Tecoma stans can be pruned lightly any time of the year but it’s best to reserve heavy pruning cuts to the winter months. It’s difficult to kill this plant by pruning. Tecoma stans used in desert landscaping at Ethel M’s in Henderson Nevada             If this plant is getting too large for the area given it, you can cut it close to the ground and it will sucker from the base much like oleander and Lantana. It responds to this type of pruning similarly to oleander because of its size. Oleander winter pruned to remove old growth and renew the shrub to its former youth             To flower, the parts growing above ground must come back into “balance” with its roots. So, it is likely to grow rapidly without flowering until it reaches the “magic ratio” of shoots to roots when it will start flowering again. This is probably when it reaches about 3 feet in height. Winter pruning of lantana for renewing growth. Actually it could be cut back more than this and it would be better.             Yellow bells can be pruned in other ways. If the plant is getting too tall, reduce its height by cutting the tallest branches back to a crotch or the ground.             If you want it taller and expose the bottom stems or trunks, then reduce the number of trunks or stems to 7 or less, trying to keep an odd number. Cut the smallest stems just below ground and remove side branches from the remaining to about knee height.

Q. My palm tree is about 20 years old and this year put out big bunches of berries. It does not seem like a date to me because they are small and round with not much flesh around the seed. Are they edible by humans?   Palm of reader. A. It depends on the palm. Many types of date palms have been planted all over Las Vegas and these trees frequently produce a lot of fruit at several times during the year. Date palms cross pollinate easily so there is a lot of variability in fruit quality, color, size and time of year they produce fruit. Fruiting of Canary Island Date palm, fruits are edible but not desirable.             All palms I know of in the Mojave Desert produce flowers and fruit when sexually mature. The fruit ranges from delicious to inedible to toxic depending on the palm. To my knowledge, there are no palms that survive and produce toxic fruit in the Mojave Desert. There are some which produce what I call “inedible” fruit. Date palm planted in the parking lot of a Dollar General store in Las Vegas.             There are palms that produce fruit that you can eat but you don’t want to eat them because they taste awful or don’t have much “flesh” such as the Canary Island Palm and the California and Mexican Fan Palms. This boat tail grackel knows the dates on the ground are sweet and good to eat.             There are other palms that produce edible fruit in the Mojave Desert such as the Jelly Palm and the Chilean Wine Palm. As far as tree size goes, the Jelly Palm is more desirable as a landscape tree because it is much smaller at maturity than the huge Chilean wine Palm. This palm lays claim to the largest palm in the world!             Watch the birds. If the birds pick up the fruit from the ground and eat it, it’s probably edible. If birds leave it alone, it probably isn’t.

Q. How can you increase pomegranate fruit size? Beautiful fruit color and size of ‘Sharp Velvet’ pomegranate variety. A. First, keep in mind that some varieties of pomegranates produce larger fruit than others. That and all red fruit color is why the variety called Wonderful was selected for commercial production in the United States. If you have a variety that can produce larger fruit it generally has to do with 4 considerations; the health of the tree, no water stress as the fruit is gaining in size, how it is pruned and the number of fruit on the tree. Good size and the color is developing nicely on a not yet mature ‘Wonderful’ pomegranate. Larger fruit is produced on flowers coming off of larger stems. This has to do with how it’s pruned. Pruning should maintain older and larger wood. Pomegranates grown as a shrub with lots of stems coming from the ground will produce a lot of fruit but they will tend to be smaller. Larger fruit will be produced if 5 main stems are maintained coming from the ground rather than 50. Trees with 4 or 5 major stems will produce fewer flowers but the fruit that these flowers produce will be larger. Producing a large percentage of large fruited pomegranate relies mostly on proper pruning and irrigation. Make sure pomegranates do not get water stressed during the summer months as the fruit is beginning to get larger. I have found that a 3 to 4 inch layer of woodchips on the soil surrounding the tree help keep the soil from drying between irrigations. When several pomegranate fruit all originate from the same spot and the tree has lots of developing fruit and flowers, there is a chance that removal of these fruit when they are very small may result in larger fruit that remain Removing flowers or small fruit can help increase size of the remaining fruit (thinning) only if there are far too many flowers being produced. Proper pruning reduces the number of flowers and thinning is seldom needed. Fertilize the tree in February or March just before new growth begins in the spring. Flowers are produced on new spring growth.

Q. I keep my landscape cacti and succulents on the dry side. But I am uncertain how much water these plants use when kept outside in small to medium sized pots. They don’t have a large volume of soil to contain their water supply. Cacti are quite beautiful whether they are flowering or not. Thanks Agnes! A. You are right. Cacti are watered less often when planted in the ground. They have a much larger root system compared to those growing in containers. Landscape cacti and succulents draw upon water their roots find in the surrounding soil. Potted plants are restricted to the water found only in their container. Cacti growing in containers are managed and watered differently than cacti growing in the ground. Pay closer attention to water management and the soil needs to be changed every few years.             Surprisingly, cacti and succulents of the same size kept outside in containers use about the same amount of water as those growing in the ground. But potted plants are watered more often but given less water during each irrigation. Cactus should never be planted directly in most of our soils. Homeowners water them too often. For this reason the soil must drain easily. Soils that contain many small rocks, called course soils or coarse sand, can be used. When compost is used, make sure it does not more than 10% of the soil mix at planting.             Water cacti and succulents more often in pots and containers. How often depends on the cactus and the soil.             Cacti and succulents growing in the wild may have roots stretching distances 8 to 10 times their height. These large, extensive roots are important for their survival. When it rains, shallow roots “slurp” up the water quickly and put it into internal storage. After a rain, trunks, stems and fleshy leaves visibly swell with this stored water. They look “plump”. They react the same way after an irrigation. Cacti and ornamental trees should not be mixed on the same irrigation valve. Either the cactus will get too much water or the ornamental tree will not get enough. There is no happy medium when mixing these plants together.             Observe your plants to determine when to water next. To push growth, water more often. Water Opuntia or prickly pear cactus every three weeks during the summer to push new growth.             Watering frequently can cause excessive top growth with shallow roots. Eventually they fall over because they are top-heavy. Watering more often than this can kill it.             ALWAYS allow the soil to dry between irrigations. Look at the cactus. If they are starting to shrivel, then it’s time to water. If the container is getting light in weight, it is time to water. Most cacti roots are shallow and spread long distances. Watering cacti with drip emitters close to it is not a good idea or it can blow over in strong winds.             Use a pencil. It is harder to push a pencil into dry soil than wet soil. Use a moisture meter. The meter should read “DRY” when it’s time to water again. Avoid glazed containers that are too small for a large cacti or succulents. Many cacti experts recommend porous, clay pots with drainage holes at the bottom. The width of the containers should be about half of the plants height. 

Q. We have several different Palo Verde trees.  Last winter one had brown leaves and looked like it was dying. Come spring, it grew new green leaves and looked fine during the summer.  This winter again several of them have brown, dead-looking leaves.  What is going on? Is this Palo Verde tree dead?, The winter temperatures got cold enough to kill the leaves but not the tree. The leaves died and dropped from the tree. A.  Sometimes Palo Verde are called evergreen when, in fact, they may not be in our climate.  Evergreen in a warm climate may not be evergreen in a colder climate.  Whether they keep their leaves green through the winter is a matter of climate, weather conditions, the type of tree and how the tree is managed.   Palo Verde trees can get quite large as this native tree in Arizona can testify.             Just because they are collectively called Palo Verde does not mean they respond to winter cold temperatures the same.  Some types of Palo Verde may be evergreen during warm winters but brown leaves or drop them during cold winters.  Some types of Palo Verde trees maintain their leaves through the winter better than others.  Therefore, you’re seeing differences among the several types you have. A multi-branched Palo Verde can be a beautiful addition to a desert landscape.             If winter temperatures are warm, the leaves remain green or evergreen.  During colder winters, leaves fade to a yellowish green after a moderate cold snap.  If winter temperatures get colder, leaves die and turn brown.  They may or may not drop.  Don’t worry.  New leaves emerge in the spring and replace the dead ones, just as yours did. Flowers of Palo Verde are quite beautiful as in this Parkinsonia but they also shed a lot of pollen which can make life unpleasant for people with allergies.             At temperatures, even colder than this, leaves as well as small branches might die. Temperatures still colder?  Leaves and small branches die and larger limbs might die as well. Temperatures even colder than this?  The tree might die.  How much of the tree dies depends on how cold it gets and for how long this cold temperature sticks around.             Help trees that are winter tender by NEVER fertilizing with nitrogen fertilizers after July 1st.  Applications of phosphorus or potassium are fine, but no nitrogen.

Q. My Arizona Ash tree is about 20 years old. Six or eight of it’s limbs have dried up and died, within the last couple of weeks. Can you tell me the cause of this and what I can do to prevent more from drying up? Ash tree showing gradual branch dieback from ash decline A. Judging from your description, most likely your tree has a disease called ash decline. It is important to know the scientific or Latin name of this tree, Fraxinus velutina, because it is called by many, names in the nursery trades including velvet ash, smooth ash and desert ash among others. Ash tree showing the first stage of yellowing due to ash decline             For this reason I just tell people to not plant ash trees in general in the larger metropolitan areas associated with the Mojave, Sonoran and Chihuahuan deserts of the southwestern United States. There are plenty of nurseries still pushing these trees and they are aware of the problem. Caveat emptor, buyer beware. Close-up of leaves yellowing and scorching due to ash decline.             About 4 or 5 years ago I stopped recommending the planting of any type of Arizona ash or Modesto ash in the Las Vegas Valley. Arizona ash also includes Raywood and Fan Tex ash which are a type or cultivar of Arizona ash. We don’t have a history yet of these trees, but I would be leery of ash trees labeled as Bonita and Fan West because they have Arizona ash genetics in them. Advanced stage of ash decline where entire tree dies. This can take up to 10 years. Is ash decline capable of spreading from tree to tree? The answer is probably yes. This is the reason I am telling people to remove these trees after ash decline has been confirmed.             In the mid-1980s in the Las Vegas Valley in North Las Vegas on Modesto ash and we tried everything we could to cure, rectify and remedy this problem with no success whatsoever. The trees ultimately died. We involved the state plant pathologist who sent tissue samples to Florida thinking it was a disease called ash yellows and it came back negative.             Personally, if these trees are getting adequate water, not too often and not too little, assume it is ash decline and remove them as soon as possible. We don’t know much about the disease, we don’t know how it is spread so we should get rid of them and not plant them again until we can figure out what this problem is and how to stop it.             Look for suitable replacement trees. If these replanted in a rock/desert landscape then replace it with a desert landscape tree that will give you the same benefits. To our knowledge this disease is not present in the soil and is restricted to certain types of ash trees so replacement trees should be fine if they are not ash.

Q. I have a 15-foot tall yellow fig tree I cut back every winter to about 8 feet. It grows aggressively every year and usually fruits 3 times a year with large, sweet figs. This year the fruit wwas good but I only got about ten figs. I planted a kumquat tree near it and applied the recommended fertilizer. Did that fertilizer caused the fig to stop producing fruit? It doesn’t look like it’s going to fruit again this year. This fig tree was cut back severely. Look at the new growth when the trunk size is reduced. Fig trees can be cut back considerably and they will re-grow as suckers from the trunk. This can reduce the early crop of figs. A. It is hard to say definitively but if the tree is given an abundance of nitrogen fertilizer it will grow lots of leaves and stems and sacrifice its fruit production. This is Doubly true if the tree has also been cut back severely.Cutting it back severely stimulates new growth. It’s like giving it a big shot of fertilizer. Another fig tree pruned back severely and look at its growth the following year. Severe pruning is done during the winter months.             Plants are opportunists. If an abundance of nitrogen is available, they put excess nitrogen to the best use they can which is leaf and stem growth, not fruit production.The tree becomes more juvenile.            When a tree has lots of available nitrogen and it has been cut or pruned heavily, it is forced to grow like a young tree. When the tree has grown big enough for its roots, extra nitrogen is put into fruit production. This fig tree was 12 feet tall before pruning. Figs are produced on stems that grew last year and stems that grow this year. Basically 2 crops of figs. This 10-year-old fig tree was pruned back so the fruit produced is easier to pick from the new growth. Some of last year’s growth remains so that the early crop can be picked as well.             Fruit production slows leaf and stem growth. Nitrogen speeds up leaf and stem growth but it can also make fruit larger if there is plenty of water. So this next year it should be back in production if you reduce the amount high nitrogen fertilizers and continue winter pruning.