Q. I read your blog on pruning flowering shrubs but want to know if this information also pertains to wisteria vines? I’ve read that flowering occurs on new growth, so I am not sure about trimming it. A. In my blog I was telling people to differentiate between plants that flower early in the spring versus those that flower later in the spring. Bottom line, always prune flowering trees and shrubs any time after they finish flowering if flowering is important to you. Let me first give you a textbook answer. Wisteria falls into two major groups; the Asian varieties and the western varieties. The Asian varieties of wisteria flower on last year’s growth (early spring flowers) while the American or western varieties flower on current season growth (late spring or summer flowering). Something interesting about wisteria is the amount of time the plant needs to begin flowering. It’s usually quite a while. Some people say 10 years to initiate flowering, others say 15 years and I have even seen some people say 20 years! That’s actually quite old for a woody plant to start flowering. Typically unimproved woody plants begin flowering in about 6 to 8 years.  Plant breeding and producing hybrids that flower earlier can address this problem. When you’re pruning try to leave as much older and larger wood as possible. Prune its structure the way you want it as early as possible. A few things that can affect how soon or at what age the plant begins flowering can be removing too much larger wood, using a lot of high nitrogen fertilizers, how much shade it’s growing in to name a few. It will flower when it’s good and ready to flower. Just remember prune after it finishes flowering and you won’t go wrong. Fertilize once a year in the very early spring with a “rose fertilizer” and not a “lawn fertilizer” or apply compost in the early spring.

Q. I am reaching out to you to see if you could offer some advice on my established fig tree. I noticed that some of the leaves have turned yellow with browning at the end and are drying off. The tree seemed to be healthy up until the last couple of weeks. The fruit seems to be in good shape.   A. The fig tree appears to be okay except for a few yellow leaves. The picture you sent shows the yellow leaves in the shade or interior of the tree. That could be normal if the leaves are not getting enough sunlight they will turn yellow and drop. The most important thing is the growth of the tree and fruit production. You haven’t mentioned it’s growth but the fruit production seems to be good from what I understand, another indicator that the tree is healthy. There doesn’t appear to be a problem except the yellow leaves in the shade in the center of the tree. For those reasons I would tell you that there isn’t a problem. I would suggest however that you keep the grass away from the base of the tree two or three feet. Dig out the grass from this area and cover the soil with wood chips. Rock would not be a good idea there. Do not plant annual flowers in that area but you could put a circle of edging around the tree to contain the mulch. I would not plant anything in the mulch area but keep it free of weeds. The fig tree will get plenty of water and fertilizer because of the lawn.  It will not need anything extra. Make sure that the lawn is not getting so much water that it harms the tree.

 Growing roses in the desert is not as hard as one might think. It follows alot of the same principles of growing other mesic plants. 

  Q. About a year ago your newspaper column had a clip about stopping annual weeds & it’s in your column in the RJ this past Saturday. I had my yard re-rocked & took your advice over the advice of the landscaper who wanted to put down a screen to stop weeds. I paid extra to have him put down a 3 inch layer of rocks. I believe last year you said 3 inches & this year 4. So, now I have a lot of weeds in all of the rock areas! What happened? Black plastic mulch under a rock mulch and eventual unsightliness. A. Great questions and I apologize for any misunderstanding I may have created. I don’t have any pictures to go on so I’m using my imagination. Let me tell you my thoughts about this. Do you know that the time (and money) spent to control weeds beats out time (and money) spent to control insects or diseaseor both of these combined? It’s true in agriculture, too. Weed control is timely and expensive. Here plastic is applied under rock mulch bordering a lawn. The plastic is suffocating the roots of Italian cypress and causing it to yellow. There is some research done on the use of thicker rock mulch versus using a landscape fabric (sometimes called a weed barrier and you call it a screen). There are a number of recommendations about what to do when laying down any type of much whether it is rock or wood. The information I see on using both is either from marketing and sales of landscape fabric or from landscaping companies promoting it.  Landscape fabric starting to poke its head out from under rock mulch in a couple of years. Using landscape fabric under rock or woodchip mulch looks good in the beginning. Pro landscape fabrics The Spruce – How to install landscape fabric Bob Villa – Landscape Fabric 101 There are some sites that are against its use. This can be from informational sites or landscapers. Its not a “magic bullet” when it comes to controlling landscape weeds. Con landscape fabrics Linda Walker-Scott – The Myth of Landscape Fabric Garden Rant – Is landscape fabric ever not horrible? Plenty of contradictory information out there and I think the main reason for using landscape fabrics AND mulch is hope. This includes landscapers as well. Black plastic under rock mulch and planting. First of all, don’t ever expect total weed control from anything whether it’s by mulch, a weed fabric or both. Wherever water is applied there will be weed growth. The most common places whether there is fabric applied are not is where the drip irrigation is applied. Weed barriers do nothing to prevent bermudagrass, nutgrass and many other weeds from growing.  Whenever installing mulch, whichever method you use, take the time to kill weeds first before using landscape fabric or not. Spray marker (paint) is used to mark where weed control spray is applied to a landscape to reduce spraying weeds twice. Origin of Landscape Fabrics Weed control barriers had their start in commercial agriculture. It was then adopted to landscapes. Here black plastic mulch is used as a temporary mulch for weed control and warming the soil early for lettuce production in Kosovo. Straw is used between the beds as a temporary mulch. The most effective depth for rock to cover a surface is at least 2 inches deep. Nothing is gained by having the rock deeper than four inches. The problem in making a rock mulch two inches deep. evenly, is it takes precision. Higher areas are one inch deep and low spots are three inches deep. The best choice is probably three inch depth but certainly not more than four! That’s a waste of money. Best depth for rock mulch Hence, landscape fabrics are not recommended for weed control practices in landscape planting beds.  Non-chemical Weed Control Strategies for Nurseries and Landscapes: Part I Reason for Justifying Landscape Fabric A reason for applying landscape fabric is weed control. One reason for applying a mulch is weed control. They are supposed to do the same thing. Why apply two things for the same reason?  Applying rock mulch is a permanent layer. Landscape fabrics or weed barriers are temporary weed barriers. You are applying a temporary weed control barrier under a permanent layer. Do you see the problem that will arise if the temporary barrier fails? This doesn’t make sense to me. Using two things for the same purpose? And applying something temporary under something permanent? What to do?  If you have it under rock or wood mulch then it is there. Nothing you can do about it but it will be a big job if it has to be removed because of unsightliness. Hopefully it is not a solid sheet of plastic but a fabric that allows air and water to plant roots. That’s better but it can still be unsightly over time. Hand weeding. Most, probably about 90% of the weeds that you see at first will be annual. They can be easily removed with some hand labor and a hoe before they flower. Another option (one that I use with rock mulch) is a fire weeder like Red Dragon and propane. Make sure your municipal ordinances allow its use first. There are weed control chemicals you can use to control weeds around your landscape plants without hurting them. Try applying fusilade weed control products for grass control growing in non grassy landscape plants if bermudagrass is the problem. Look for fusilade (fluazifop-p-butyl) to be listed in the active ingredients on the label. In some cases the product is simply called Fusilade. (I agree its a lousy name to remember).  Permanent Weed Control Permanent control of weeds is impossible but you can reduce the amount of time you spend weeding. Persistence.  1. Never let weeds flower. This makes seed. “One year weeds, seven years of weeding.” (old gardening adage). Remove them before that happens. 2.

Bottle trees (Brachychiton populneus and locally called Kurrajong) are Australian native trees found in the northern tropical and subtropical climates there. They are classified as “drought deciduous”. Drought deciduous just means they start dropping leaves when the soil gets dry from September through December every year. For B. populneus the swollen roots are thought to store water for dry periods. The other common Bottle Tree, (Brachychiton rupestis), does this as well and has a trunk with more of the traditional “bottle” shape. Both grow too tall and large for most home landscapes. They can be grown in lawns if not overwatered and you make sure the soil will drain fast. If these trees are watered too often or the soil does not drain well, the roots of the trees can suffocate and the trees die. Bottle tree with horizontal limbs and thin bark gets sun damage and can drop its leaves if the damage is severe. This tree has thin bark that should be protected from intense sunlight and vandals. They are thought of as “desert trees” but they aren’t. The intense sunlight of the desert can burn their horizontal limbs and, if enough damage is done by the sun, the leaves will drop. 

Q. I have a 25-year-old fruitless cherry plum tree in my backyard. It is a beautiful tree, and has grown wonderfully through the years, however it has not been fruitless.  Some years have had more fruit than others, but the last few years it has been covered, with tons of fruit, making a real mess and attracting ants and rats. I was told that there is a spray that will stop it from bearing fruit. I found something called Florel, which you apparently spray on with a hose, at the perfect time between mid and full bloom in the spring. Will this work? Will it hurt bees? This is a cherry plum called ‘Sprite’ , a Myrobalan plum used for fruit production. The fruit has a very high sugar content but very sour. Some types of Myrobalan plums are used as ornamentals. A. You did some good investigating. It must be applied when it is flowering. It is safe to use around honeybees and other pollinators that might be present during the flowering time.  For any of these “fruit eliminator sprays” it is important that the flowers are open so the spray can reach inside the open flowers and cause the ovary to abort.  This is a fruit eliminator product, Florel, that can be used as a spray to eliminate fruit and seed of plants. The spray will not hurt bees. Yes, Florel will work. It is best to spray when the flowers are starting to open (20% of the flowers are open) and repeat the spray when the first flowers that open are shedding their petals (80% of the flowers are open). Flowering can take two to three weeks for all of the flowers finish. The first flowers to open are those in the warmest parts of the tree (usually south, west and tops of trees) and the last to open are on the north side and those in the shade. Follow the label directions for mixing the spray with water. It won’t get all the fruit 100% but most of it.  It is sometimes called flowering plum and it is a fruit tree. It has been selected as an ornamental because of its beauty. In the fruit tree industry it is sometimes used as a rootstock for fruiting plums and peaches and called Myrobalan plum or just plain old Myro. The fruit has wonderful flavor, very tart but full of sugar and makes a wonderful jam or jelly. 

Q. Can you also guide regarding quality of seeds and plants and recommendation for places where to get them from? Any guidance how I can improve my crop for next season? A. Use tried and true vegetable varieties that have performed well in desert locations in the past. Make sure your vegetable seed and transplants are in good shape at the outset. Avoid purchasing seed from open locations unprotected from the elements. Dont buy transplants that appear sickly or have a problem. You are not a plant “rescuer” when it comes to problem plants. They wont perform very well. Usually the east side of walls or buildings in full sun give the best protection from late afternoon damage from sun and heat. I get emails from newcomers to vegetable growing in the desert that try vegetable varieties with marketing claims of “amazing results” from newer varieties. Introduce newer untested varieties in small numbers and notice which do well.  Some suggested varieties to start with include: Vegetable Varieties Asparagus – UC 151 Beets – Detroit Dark Red Bush Beans – Contender Broccoli – Packman Cantalope – Hales Best Carrots – Chantenay Cauliflower – Snowball Cumber – Straight Eight Eggplant – Thai Long Purple Garlic – California Early Hot Pepper – Jalapeno Kale – Russian Red Lettuce – Red Sail Onion – Yellow Granex Peas – Knight, Cascadia Sweet Corn – Sweet Rhythm Sweet Pepper – Red Beauty Potato – Red Pontiac Radish – Cherry Belle, French Breakfast Spinach – Melody Tomato – Sweet 100, Roma Watermelon – Bush Sugar Baby Zucchini – Black Beauty Windbreaks Desert climates can be finicky. High and sometimes erratic temperatures can be a problem along with wind and low humidity. Probably the most overlooked climate variable that will improve production and vegetable quality the fastest is controlling the wind.  Did you know the best production occurs just downwind of a windbreak? They slow wind speed down considerably to a distance of about five times its height.  Four foot tall chain link fence with PVC slats work well if installed downwind of the growing area’s prevailing wind and doesn’t require much maintenance or any water!  Windbreaks made of chainlink and PVC slats slow the wind enough to qualify as a nonliving and waterless windbreak in desert climates. Grow in Containers Growing vegetables in containers makes it easier when there is a problem. Five gallon containers and larger give the plants enough soil volume to hold water in the soil for at least one day during the summer. When you want to increase your growing area try containers first. They are best located on the east side of a wall or building and the container shaded from the hot sun by the raised bed, other plants, or double potted.  No crop rotation is necessary. Just use the soil from the container for a different crop or cropping season and reuse the soil somewhere else and clean the container, if you use it again, when it gets “worn out”, full of diseases like Verticillium or nematodes.