Q. I recently purchased some Green Cloud Texas Rangers from a building supply store and was wondering if it is safe to plant them now since our weather is turning colder. A, Since you emailed this question to me it froze in parts of the valley this past week. But not to worry. This kind of weather can be freakish this time of year. It normally does not freeze until the second week of December. But the ground is still warm. After you plant you want the roots to grow but you should not care about the top growing yet. The best planting time for woody plants is from late September until mid-November. You can still plant at other times but its just not as good because of root growth.             The ground is still warm enough to plant. The magic number for landscape plant root growth is about 50F. Of course, roots of plants grow faster in warmer soils, but they will still grow at 50F. The ground never froze or was even close to freezing. The soil temperature rises up and down mimicking the air temperature, but these temperature swings are much smaller compared to air temperatures. For instance, in some areas vegetables like tomatoes, peppers and squash froze, but the ground never did. The soil in the ground was much warmer than the air.             If you want the soil to warm up fast then keep it dark, fluffy, dry and in the sun. Those kinds of soils have wide temperature swings from very warm to very cold but still not as cold as the air. Landscape plant roots like to grow in those warm temperatures during the day. Soils that are not fluffy, wet and instead are covered by a surface mulch or in the shade stay cooler and don’t swing up and down as much.             Surface mulch keeps soils warmer in the Fall and cooler in the Spring.

Q. I have two desert ironwood trees that are ten years old, 12 to 16 feet tall, in my landscape. A nursery told me I should water these trees deep daily for 7 to 10 days. I did that and after the third day the leaves turned a pale yellow and fell off to the touch, so I have stopped watering. The soil moisture meter I use is showing 7 to 8. Any thoughts because I really don’t want to hurt these beautiful trees. A. When you call these trees “desert ironwood” I am guessing you mean the ironwood native to the Sonoran Desert. It’s a beautiful native desert tree that does not need to be watered very often. It is considered an indicator tree for growing citrus so during cold weather in southern Nevada it might get damaged. There are other trees called ironwood as well.             Because it grows in the desert, it is not used to getting water very often. When you water this tree, irrigate the area under its canopy to a depth in the soil about 18 to 24 inches. Then don’t water again until the soil dries out. Because it’s a desert tree, it will not like wet soil but soil that occasionally gets wet. That’s why the leaves are yellowing and falling off; watering is too often and the roots are suffocating.             On the soil moisture sensor, or meter that you have, the needle should be in the three or four spot before you water again. The meter reads zero to ten with ten being sopping wet. You want the soil to be on the dry side about six inches deep, not the wet side when you water it again.             When you do water, try a hose, an inexpensive sprinkler that screws onto the end of the hose and a mechanical timer that shuts off the water. If you are like me, I forget to turn it off. The mechanical timer will shut it off for me. Set it for one hour. Take a length of rebar and stick it into the ground in three places and make sure the water got to the right depth. If the water isn’t deep enough then water for 15 minutes more.

Q.  I am looking for plants that bloom all season long like lantana. Can you help me? A. I would rather that you use a searchable plant database online like the one created by Southern Nevada Water Authority. It’s a good one. Google or use your favorite internet browser and type in “find plants SNWA”. The Sunset Zone for Las Vegas is Zone 11. The rest of the information needed for the database should be straight forward. Use this before you go to the nursery and get a list of plants that you want.             If you want plants selection advice from me, ask for five suggestions at your nursery and then I can help you pick which might be best. There is a lot of information available to help you decide. Select trees and shrubs that you cannot afford to lose using a minimum winter temperature of 20F. If we have a few warm winters in a row then you won’t lose anything!             If you select plants that tolerate winter temperatures above this temperature then expect to lose them occasionally during cold winters. Even at 20F we will have 30 to 50-year freezes that will get as low as 12F. If the 20F plants are established in the landscape well before that, they will probably survive.

Q. I made a couple of raised bed planters for tomatoes and peppers and currently have garlic, spinach and lettuce growing. Would adding worms to the soil help? A. Worm benefits far outweigh any feeding damage they do to plant roots. I know I will get some heat for saying this, but earthworms can create some damage to small plant roots. Just like ants can carry away seeds that you plant. Too much of a good thing can be too much.             If you do add some earthworms to your garden plot, you don’t need to add many. They multiply quickly when organics and moisture are present. The addition of compost to raw desert soil and growing plants in it is usually enough. I will see earthworms in soils that I amend and cover with woodchips in abundance the first year after planting. Adding worms to your soil will speed up what will occur naturally. 

Q. My Italian cypress had spider mites, so I sprayed the trees with an insecticide about six weeks ago. Nearby Italian cypress trees are also full of spider mites. I was going to spray them with an insecticide until I listened to your Desert Horticulture podcast which told me to use a miticide instead. Which one should I use? This Browning could be from spider mites, watering too often, or borers. If it occurs in the middle of summer it’s very likely spider mites. A. Spider mites are a hot weather insect so spraying when it’s not summer just for them doesn’t make much sense. However, spraying oils in Fall and Winter months makes perfect sense for insects that might spend the winter on your trees. Horticultural oils, sometimes called dormant oil or spray oil, is the best insurance to prevent insect outbreaks like aphids, spider mites, and scale insects.             Remember, spraying insecticides make mite problems more likely on susceptible plants like Italian cypress. Miticides, unlike insecticides, are less likely to cause mite problems later. Spider mites are nearly always present on all plants they feed on. There are lots of insects that feed on spider mites as well and keep them in check. Spider mites, like their name suggests, usually leave a webbing that you can see when there is damage.             These predatory insects hunt down spider mites and use them for food. Think coyotes and rabbits. Spraying traditional insecticides like Malathion, Sevin and even organic insecticides like Neem oil or soap and water kills most insects off, good ones as well as the bad one you wanted to control. The primary benefit of organic sprays are its environmental safety and short life after its sprayed. When spider mites are active they can create a bluish green cast when they are actively feeding and often times then leaves of Italian Cypress are “dusty”. Spider mite damage always starts in the heat of the summer.             If an insecticide must be sprayed for some reason, watch the sprayed plants very carefully during hot weather to see if spider mites become a problem or not. Frequently spider mites will become a problem after spraying an insecticide because their predators were killed. I realize sometimes you must, but spray insecticides as a last resort. Close-up of the needles or foliage of Italian Cypress and spider mite damage.             Miticides are chosen because spider mites are more like spiders than insects and sprays that kill insects oftentimes don’t kill spider mites. I am glad you did not use an insecticide for mite control. It would have made the problem worse and probably not killed the spider mites.             Use the University of California Integrated Pest Management websites (“Google” them by using your favorite search engine and typing in “UCIPM” and “spider mites”). Read these notes. They are written by entomologists who specialize in controlling pests. After reading these notes you will be better informed than 90% of the landscapers spraying plants.             The UCIPM notes will recommend spraying oils like canola, clove and cinnamon oils as well as horticultural oils and sulfur sprays to control spider mites. In our hot desert environment these sprays may damage plants during the hot months. It is cool enough in the Fall, Winter and Spring you can spray oils without damaging most plants. Plants that may be damaged will be listed on the label.

Q. I had a lot of borer damage to my trees so last summer I cut out most of the large branches and reduced the height of the trees to about 10 feet and let them grow back. Then I treated the soil with an insecticide, surfactant and fertilizer. That was my counterattack regarding the borers. Borer exit holes in the trunk of Italian Cypress sent in by an alert reader. A. Make sure trees that you do cut back will grow back. Some trees like most ash trees will not grow back very well if they are pruned severely. Also make sure the pruning instruments are all sanitized before pruning. This formulation of imidacloprid (this name is found under ingredients) is probably the most common one found on shelves. Shop around because there may be some that are less expensive. Compare the percentage of imidacloprid on the label with the price of products. Higher percentages single just means you get more “bang for the buck”.             Insecticides like Imidacloprid (active ingredient) used as a soil drench (mixed with water and contained on the surface of the soil above the roots) are systemic and taken up by roots of the tree and kill many types of borers. Whatever insecticide you use should be systemic and have a label that says it is effective against wood boring insects. Excerpt from the product label of Imidacloprid 2F manufactured by Prime Source LLC. The active ingredient is available from several manufacturers so it is imperative to read the product label before making any applications.             If the insecticide has “staying power” inside the tree then I would apply it after the tree flowers. This is usually in early spring. Long-lasting, systemic insecticides like Imidacloprid are suspected to harm honeybees. There is a possibility the insecticide could be available to honeybees if it is applied just before flowering. A portion of the product label for Imidacloprid 2F warning about killing honeybees. Be careful when you spray insecticides or apply them as a drench to the soil.             I am not sure why you are using a surfactant unless it is to help this insecticide drench move into the soil faster after drenching the area. Surfactants are a very broad category of  spray additives but usually used to move liquid fertilizers, insecticides and fungicides inside plant leaves when they are sprayed. One example of a surfactant. When mixed with a spray it helps the product get inside leaves or stems. When mixed with a liquid drench it might help the drench move into the soil better. 

Q. My Italian cypress are getting too tall. Can I top them to keep them smaller? Here a homeowner “topped” their Italian Cypress to control its height. It works but it will increase the width of the tree through new growth to the sides rather than directly upward. A. Topping trees is not a good idea but in this case it will work because underneath all that foliage is a central trunk. It’s not the best way to handle this dilemma but if it is done when the tree is smaller it will help prevent it from getting too tall. Removing several feet of the top this way is questionable.             Remove the pointed top just below the height wanted. This keeps the tree’s height in check, but it will grow wider than if it were left alone. Hindsight is 20/20. It would have been better to realize these are 40 to 60-foot trees before buying or planting them. Sometimes the top will die in Italian cypress from borers or spider mites. The top is dead. Removal of this debt growth and the removal of living growth on other trees at the same height will limit its maximum height but not its width.             The bad pruning method is shearing the tree with a hedge shears. Shearing does prevent long “floppy branches” from developing but it causes other problems. Shearing increases the density of the tree in the outer few inches while the inside branches become naked. The inside of the tree gets darker and darker as shearing increases, and this prevents any greenery from forming. Italian Cypress has such a dense canopy that anyone using a hedge shears to prune them has to be very careful not to cut into the brown area just an inch or so to the inside. This growth is very slow to grow back or doesn’t grow back at all.             Eventually any deep cuts past these three or four inches outside edge will expose the naked larger branches inside which have no greenery. None will develop from old wood on Italian cypress, so it won’t grow back. Worse than a bad haircut!

Q. I am purchasing some Italian cypress as a visual barrier between my neighbors and myself. I understand they are evergreen. Any thoughts? Italian Cypress can be 40 to 60 feet tall and 4 to 8 feet wide so make sure you have the room for them. General rule of thumb is to use small trees for single-story homes and medium-size trees for two-story homes. It’s an added expense if you have to keep pruning them to keep them at the right size. A. Italian cypress is a big tree so make sure you have room for it, and it is in scale with your home and landscape. It can be 40 to 60 feet tall and 4 to 8 feet wide. It is a good visual barrier but tall!             Italian cypress is a Mediterranean plant, not a desert plant. This tree came from climates with cool wet winters and hot dry summers so don’t water too often but more often than true natives! Put it on a valve that waters palms, fruit trees, other landscape trees and shrubs but not with lawns, flower beds or vegetable beds. It will not like it if it is watered with the same frequency as cacti and native desert trees like Palo Verde and mesquite unless they are watered too often! One sign they are watered too often is when the growth gets so much that it starts to droop. An occasional drooping branch can be pruned back to the inside of the canopy and removed. It’s a problem if you have lots of these drooping branches and it is a poor alternative if you must wrap them with green tape. Learn how to water them properly.             Italian cypress with long drooping branches is a sign it is getting too much water. Either it is watered too often, or the soil is not draining water fast enough. Hedge shearing (not recommended) keeps them in check but using a hand pruner instead is a better option. Shearing them with a hedge shears is one method to make them look pretty and keep them in bounds. But that is expensive to do twice a year.             Enough water should be applied each time to wet the soil to at least two feet deep. The amount to apply varies because of the soil so you will have to play around with the number and size of the emitters. But when you apply water, it should wet the area under the canopy out to the ends of the branches. Normally I will tell people AT LEAST half the area but these trees are narrow and upright so water the entire area.

Q. How far apart should I plant my hedge shrubs to make a hedge? A. It depends on the plant but a general rule of thumb for shrubs that grow just as wide as they are tall is to plant them the same distance as their mature height. If you plant them this far apart they will grow up touching each other. If you want them to fill in faster, then plant them a bit closer. Pruning shrubs with a hedge shears tells me you don’t know how to prune.             Planting them too close together causes them to grow together but they will shade each other. That’s not a problem for the hedge but you will spend more money than you need to in plants. These shrubs were planted too close together. You can tell because its all a bunch of wood stems at the base. A way to correct this problem now is to remove every other shrub and cut them back to their distance apart and cut the biggest branches to about 8 inches off of the ground. The hedge should fill in again in 2 to 3 years depending on how fast they grow. 

Q. Do you have any advice on digging and transplanting a Sago palm this time of year? It’s the roots I’m considering. I failed last time maybe because it was too hot. Nicely cared for cycad or Sago Palm A. The ideal time to move sago palm, or cycad, is in the early Fall or early Spring but you can do it now even though its cold. It’s just not optimum. Evaluate your situation. If it has been in the ground more than three years, it is more difficult to move without damaging it. It helps if it was drip irrigated with no other irrigation within 10 feet or so. This isolates the roots and keeps what you need to move closer to the plant. These plants like a little bit of shade or protection from late afternoon sun. They just do better.             Two things are important when you move a plant: take as much of the roots and soil as possible during the move and reduce the top by 1/3 to compensate for root losses during the relocation. You will have more success if it is moved into a spot with light shade, not full sun.             Here’s the process. I will put more information on my blog for you. Cycad transplanting process             Remove fronds from the bottom toward the top so the remaining fronds are no more than a 45-degree angle from horizontal. The central fronds should be protected. The older palm fronds can be removed. Sago palm grows from the center straight up and the fronds become lower with age. Mark which side of the plant faces north. You will orient this side to the north again when planting.             Prepare the soil and hole in the new location so you can place it into its new home and plant it as quickly as possible. The hole should be about the same depth as the rootball you are moving. The hole with amended soil will be much bigger.             Move everything away from the sago palm so that it is surrounded by bare soil and then water the soil until it is sopping wet. Using a sharp, clean shovel, slice the roots of the palm at about 12 inches from the trunk. Otherwise, leave it undisturbed. The next day after water has drained, leverage the plant upward carefully from its old location while cutting any remaining roots that might hold it back.             Placing the rootball and plant on an old piece of carpet or strong fabric by lifting the rootball, carefully move the plant to its new location without breaking the soil around the rootball. Very important.             Orient the sago palm with the north side facing north and backfill around the rootball using amended soil as a soil slurry to remove air pockets. It will not need to be staked. Add any amendments to the soil you feel is necessary to improve rooting. I personally don’t use anything more than the amended soil.             After the soil has settled and starts to dry, cover the area surrounding the sago palm with woodchips. Woodchips are a better soil covering (mulch) than rock for sago palm.