Q. I have been wanting to plant a tipuana tree since I saw one in person (those pinnate leaves are gorgeous!) and I love the idea of a wide canopy.  You mentioned in a December 2013 blog that here the potential for damage from the roots would not be as concerning in Las Vegas as in other places as long as it was planted “several feet away from foundations, etc.” The location where I would like to plant is between the pool and the block wall.  The wall and the pool are separated by 19 feet.  Would planting 4 feet from the wall and 15 feet from the pool be reasonably safe? I have citrus, duranta repens, and some other cold sensitive plants that I dress in old school Christmas lights and wrap in frost cloth, so I understand it will take extra work to protect from the cold.  What do you think of my chances for success? A. Just to be a little more clear than the section you read in my article. I am not a big fan of this tree but it has been pushed for planting in the Las Vegas area by a local nursery. You should read some of the comments from Arizona State University (Mesa, AZ) about its use in Phoenix. http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/tipuanatipu.html If you plant this tree please be prepared that: It may freeze back during some of our winters in Las Vegas when winter temperatures get below 25F. In the past our winter temperatures have dipped regularly into the upper teens. It is not low water use. Expect that this tree will use more water than desert adapted trees of a similar size. So plan on using it in a part of your landscape that is wetter and not surrounded by rock mulch typical to desert landscapes. Tipu dieback This is a big tree. It can get to heights probably 35 to 50 feet tall in the desert. It routinely grows higher than this in nondesert landscapes. /tipu canopy So if you are fine with all this then I would not plant it closer than about 10 or 12 feet from a house foundation, patio, driveway, wall or sidewalk. When you plant it, focus the applied water in areas away from these areas. Try to leave at least three feet of dry soil between the tree and these locations. Nine times out of ten you will be fine closer than this but it is the 1 in 10 that concerns me. It should not be used in a hot part of the yard with lots of reflected heat and light. Sapsucker damage on tipu I have seen this tree in backyards that are protected from wind and with plenty of plants around it. I have seen them up to 20+ feet tall and looking pretty good but these are protected backyards. Tipu growing in backyard These are relatively new trees for Las Vegas so there is not much history on them. But I am always concerned when planting any long term tree that is freeze damaged at 25F in a climate that historically gets lower temperatures than this. I have a saying that I tell my students…be prepared to spend more time, energy and money on plants that may not be sustainable in our desert climate. I like to see trees that are key elements to a landscape that will survive winter temperatures at least to 20F.

Q. I have one pomegranate tree in bad shape. The leaves are turning yellow and then brown, underneath the veins are pink. This is one tree out of my 50 that looks like this each other tree look great with a lot of new growth. Any ideas what could be happening with this one tree? A. Yellowing of the leaves could be caused by several things including flooding the soil too often, poor drainage and planting too deeply. However, if these trees have been growing for several years, you have done nothing differently and suddenly the leaves turn yellow, it could be damage from weed killers used in the area.             Remember, apply weed killers only when there is no wind and temperatures are cool. Best times are usually spring and fall. Some weed killers can vaporize into the air when sprayed during the heat. Slight wind movement causes these vapors to drift onto the leaves of valuable plants nearby and damage them.             Never spray weed killers when the wind is strong enough to move plant leaves. Use leaf movement as an indicator whether to spray or not. Early morning hours are usually best.             Some worst offenders in this category are the lawn dandelion and similar weed killers. These types of weed killers move easily with air movements and cause leaf distortion, leaf yellowing, leaf death and even plant death.             If the plant is actively growing when weed killers accidentally drift onto the leaves, then wash the leaves with water as soon as possible. Diluting weed killers with water while the leaves are still wet helps prevent damage.             All you can do at this point is wait and see what happens. Fertilize it normally and water it. But remove the grass at least 2 to 3 feet from the trees and fertilize it with nitrogen fertilizer. Another possibility could be salinity…salts…but you should see some leaf tip browning.

Q. I have two of these plants at my front door area that are two years old. They only bloomed the first year and this year they are very green but no flowers. How do I get them to flower?  I tried cutting the water for 2-3 weeks but that only made them grow and greener. I would appreciate any help and suggestions you may have. I have attached pictures of them. A. Flowering requires at least 8 hours of direct sunlight everyday. If they are not getting enough they will be a nice green, grow well but flowering will be greatly reduced or eliminated. Over-application of rich soil amendments or high nitrogen fertilizers can also delay or decrease flowering but make a nice green plant. They might flower the first year because flowering was already started or flower buds were in progress from the nursery. If you don’t have enough sunlight in that spot you will have to move them to a sunnier location or out further into the light. If this was from high nitrogen fertilizers or soil amendments just let the nitrogen get used up and they should start flowering when that happens. When fertilizing, use a tomato or rose fertilizer and not a lawn type fertilizer. The others have the right balance of nitrogen and phosphorus for flowering.

Q. My husband really wants to plant a tamarind tree from seed. My question: is this doable here? I know it can get to be a very big tree but he says he will see to it that it’s pruned well. Being a tropical tree, will it survive our winter and adapt to our climate when established? As my backyard is not that big, we will be planting it about 10 ft from the house. I am concerned that its litter will be problematic when it gets to be as tall as the lower part of my roof, like the wind blowing it’s fine leaves into the nooks and crevices of the roof tiles (that’s why we removed our mesquite). My husband is from Cavite, Philippines, and this is one tree he misses a lot. These are our tamarind tree at our farm in the Philippines. Tamarind is a tropical tree that will not survive very cold temperatures as we find in most of the US. There is a  sweet and sour form of this tree. They begin to flower and produce fruit from pods when they are about 8 years old. This one is about 7 years old and I pruned it last year. A. Forget the tamarind tree in Las Vegas if you want a consistent production. It is tropical and will not survive undamaged or it will die during a cold winter in Las Vegas when temperatures drop below freezing. If it does survive the first few years, its because of a lack in winter freezing, it will get damaged or even die when it does freeze.  The extent of damage depends on how cold it gets, for how long and the age of the tree.  We have tamarind on our farm in Batangas (I am here now and can see it from here) but it is truly tropical. It will not produce any pods for about 8 years if planted from seed. Our tamarind is now flowering and fruiting because it is 8 years old. Pick a tree that will survive the cold.  It would be a shame if you were to plant it and it gets four years old, big and then there is a freeze. You might lose the entire tree and it does not sucker well from the base as some other tropical trees can like horseradish tree (Malungay).which can be cut close to the ground and it will sucker.. It is better suited to warmer dry climates like the warmer, dry Sonoran Desert. For more information on Tamarind growing in the US try the Rare Fruit Growers fact sheet on it. Click here.

Q. Here’s a fascinating palm tree photo I’ve taken in Las Vegas of a date palm, a monocot,  bifurcating at about 30′ above the ground into a dicot. There are several of these bifurcated  date palms in the same parking lot. What is the reason? A. I will post it with an explanation. It is not common but occasionally things like this occur when the terminal bud is damaged but not killed and regrowth from the terminal bud creates multiple new growing points. It has such strong terminal growth that it created two instead of more. Sometimes it creates only one new one. The alternative would have been death of the entire palm. What caused the damage? Who knows. Bugs, disease…physical damage during transport…

Q. I have a Mexican bird of paradise that was planted five years ago that suddenly died. It had flourished until now. I pulled out the plant and sent you some pictures of the dead plant, girdling or circling roots and borers that I found in the center of the stem that probably killed it. Red Bird of Paradise dead in the middle of summer A. I read your question and looked at the pictures with quite a bit of interest. This is the first time I have heard of flatheaded borers infesting Mexican bird of paradise. These are the same borers that attack fruit trees and landscape plants.             Flatheaded borers, when they are young, feed just under the “bark” of the tree in the living vascular tissue. The center of woody plants is not living so they stay feeding where they can find water and nutrients. Essentially, they tunnel just under the bark and parallel with it in a random pattern. Flatheaded borers pulled out of the stem of Red Bird of Paradise             It is here that these larvae find the most nourishment for growth. When they get larger and ready to pupate or turn into the winged adult beetle, they burrow towards the center of the plant where there is not much nourishment. But this area does offer them protection.             Here they begin their metamorphosis until they finally emerge as the adult beetle which flies away, mates and the female lays its eggs on the outer surface of susceptible plants.             It’s not unusual to see some tunneling toward the woody center of limbs or stems. Or at least inside the wood of some plants.             Girdling roots, larger roots that grow in circles, occur in plants when they are very young at the nursery. The roots of these plants are crammed into small nursery containers where they start growing in circles. They are then moved to larger containers where they continue to grow in circles. Girdling roots of Red Bird of Paradise probably started when it was first planted from a seedling.             They are then planted in the landscape where they continue to grow in circles. Gently remove plants from their containers and check for girdling roots before purchasing them. This is the only way you would know if they are girdling or not.

Q. Would it be safe to plant a flowering plum tree in September or October or should I wait until spring? This plum will look fairly good in this climate if the soils are amended at the time of planting and the soil is covered with about 4 – 6 inches of woodchips A. I would wait until maximum daytime temperatures dropped down to the low 90s or high 80s. In Las Vegas that would probably be late September or early October. I would be comfortable planting trees until about 1 November. Summer temperatures are just too hot for planting             There are plants that like to be put in the ground when it’s hot. Palms are an example. They don’t like to be planted when it’s cold. The cut off for planting hybrid Bermudagrass is the end of July. It needs about two months of hot weather to knit into the soil.             Actually, Fall is an ideal time to plant if you can find the plants you want. Fall planting gives you two times when the weather is nice; fall and the following spring.             If you find a tree on sale now it will take a lot of diligence to keep it from getting damaged because of the heat. I would put it on the east side of the building and make sure it gets protection from the late afternoon sun. Or put it in filtered light.             If it’s in a 5 gallon container, I would water it twice each day; once in the morning before it gets hot and the second time in the afternoon. Don’t let direct sunlight directly on the container. The surface temperature will heat up to about 160° F in just a few minutes. It can kill half of the roots inside the container facing the sun.             Get a second container the same size and put some large rocks in the bottom and put the containerized plant inside of it. It’s called double potting. That will help keep the heat off it.

Q. I have a dwarf peach tree that was about a foot when I planted it last year. It has grown about 6 inches now. When can I prune it so it doesn’t grow taller than me?  I am only 4 feet 10 inches and I don’t want it to grow tall because I’m going to net it. Miniature (genetic dwarf) peaches. Actually three of them planted in the same hole but 18 inches apart, one “high head” (grafted tall) and two low head (grafted low).. A. I want to mention a couple things regarding your question. First, perhaps you mean it is a miniature peach and not a dwarf. Sometimes miniatures are also called genetic dwarf trees. To remove confusion let’s call the genetic dwarf trees “miniatures”.             Sometimes the nursery trade calls peach trees grafted on certain types of rootstocks as dwarf. It’s true they are a little smaller because of these rootstocks, but not much. The term dwarf is more of a marketing ploy as far as peaches go. Genetic dwarf or miniature peach.             Genetic dwarf or miniatures are truly much smaller than the so-called dwarfs. They also grow differently and produce their fruit on branches differently. They are truly dwarf compared to standard -sized peach trees and the other so-called “dwarfs”.             If you have a genetic dwarf or miniature peach, then it will be pruned much differently from other peaches. You want limbs coming from the trunk as low as possible. Bend these limbs toward the ground, like they have a fruit load on them. See if the fruit might touch the ground.             If the fruit might touch the ground, consider removing the limb or at least cutting it back. Cutting it back might “thicken” and strengthen the branch and give the fruit more support so they don’t touch the ground.             At this point in its life you just want it to grow. If it has side branches coming from the trunk at around the height of your knee, then it is doing it all on its own. If it’s a single stick and thick as your little finger, cut it at knee height. This cut will cause this solitary stem to start branching. Bird damage on peach. If the fruit is firm (not hard) and you see this, pick!             Secondly, why are you using a net? Birds? Harvest the fruit within one to two weeks of its normal harvest period as soon as bird pecks of the fruit are seen. Let the fruit finish ripening inside the house and off the tree. It is still considered “tree ripened”.

Q. I have a common lawn with my neighbor and it has an infestation of nutgrass that is now spreading into my lawn. How do I stop it? I’ve read sugar is a good alternative to herbicides but I would like your help to get this under control. Nutgrass or nutsedge looks like a grass but it grows faster and it can have darker green leaves if it is purple nutgrass. A. I have never heard about sugar used to control weeds. That is a new one on me.             Nutgrass, sometimes called nutsedge, is a tough weed to control. Because it’s a sedge, the leaves look very similar to lawn grasses like fescue. Many people don’t know it’s in a lawn because it looks similar to the grass. It does grow faster than lawn grass and that can be a giveaway. It’s also more upright in its growth so that can also give it away. And, of course, when it sets flowers and seed that can give it away. If you look closely you can see the nut , the namesake for nutgrass. This is its survival mechanism when things go wrong.             Nutgrass is called that because of the “nut” or tuber that grows below ground. It’s usually brought into home landscapes as a weed when buying nursery plants. Most people think it’s a grass and pull it but the nut in the soil is left behind. The plant and its soil are planted. From there it spreads.             When it’s pulled like a weed from the soil, the leaves separate from the underground nut easily. The underground nut regrows new leaves. If the leaves are pulled over and over, as soon as you see them, the nut eventually gives up, exhausted, and dies. That is a common “organic” strategy for controlling nutgrass without chemicals. Very sturdy nutgrass plant probably because it was growing in a vegetable garden.             It’s also a common strategy when using chemicals. Weed killers burn the top of the plant down, over and over, until the nut just gives up.             A weed killer that can be sprayed on the grass and only damages the nutgrass is available. It is called “Sledgehammer”. It’s only available for purchase online. In prior years it was only used by professionals. That formulation was called “Manage”.             A similar strategy is used when spraying Sledgehammer. But sledgehammer actually kills a fair number of the nuts as well. But not all of them. So, it must be sprayed again when the leaves appear. Sledgehammer available from Walmart             When to make the second and third applications is very critical. The spray must be applied when the nut has “invested” its energy into the growth of new leaves. Wait too long and the leaves will rebuild the nut. As soon as they appear, no more than four leaves, Sledgehammer is sprayed again. Eventually, after repeat sprays at the right time, you have won the battle.

In the middle of summer this is what catches your eye. Limb dieback. Borers in peach tree. This is the time of year when borer damage in trees and shrubs is most obvious. Limbs are dying. Their damage can be seen from a distance now but they’ve been working hard feeding on the inside of trees and shrubs for months. The telltale sign of borer damage is a single limb or branch with leaves that turn brown and the branch dies. That’s during dry weather which happens a lot here. Sometime borers will catch your eye because the bark is peeling off the trunk.  Borers in ash tree.             Borer damage is often times associated with damage to plants from intense sunlight, sometimes called sunburn or sunscald. Damage is often times seen on the hot exposures of a trunk or the upper sides of limbs. A good strategy is cautiously prune plants that get borers. These include many fruit trees, pyracantha, Arizona cypress, loquat, several types of landscape trees and shrubs. They either cause or are attracted to plant parts damaged by the sun like the upper surface of branches or the south or west sides of the trunk.             One borer in a small branch can kill it. But it takes two or three borers feeding in the same area of a limb to cause a larger branch to die the same season it is attacked. It’s probable that borers were present in trees, chewing away on the soft succulent inside just under the bark, for years before obvious summer dieback is seen. The larva (borer) of the adult beetle can be found feeding on the inside of the tree, just under the bark. Borer in Red Bird of Paradise.             Resistance to borers depends on the health and age of the tree. Healthy trees withstand several attacks by borers before damage is seen. Smaller sized trees are easily killed while larger ones are more resisitant. Sometimes trees are healthy enough that damage is never seen and they “outgrow it”.             The best time to inspect a tree for borer activity, even if you don’t suspect anything, is immediately after a rain. The rain “softens” the surface of limbs or the trunk. Tree sap associated with the feeding of borers oozes from the trees, at the damaged area, resembling varnish remover oozing from the trunk or limbs. Sap, either dried or still gooey, can be a dead giveaway of borer activity in some trees. Some trees are just naturally “gummy” and so you cant tell.             If there is a lot of “varnish remover” coming from a limb or trunk, then there is heavy damage in those areas. Take a sharp, sanitized knife and remove the bark from the trunk or limb. The borers, or flat headed “worms”, lie just beneath the surface in those damaged areas. Remove them and cleanup the wound and let it heal. If damage is too severe, remove it.