November 2014 – Page 3 – Xtremehorticulture

African Sumac Needs More Water As It Gets Larger

Q. We planted an African Sumac tree three years ago that is showing a lot of new green leaves now. Could you please let me know how much water it needs? It was deep fertilized at the beginning of spring. A. Are you sure you aren’t seeing flowers? These trees flower in late Fall and into the winter months in the Northern hemisphere. African sumac flowers You realize that trees require more water as they get older and larger. So at three years of age they require more water than when first planted. I would normally add another emitter at this age to give it the extra water it needs. In another three or four years it will require again more water than it requires now as it gets even larger. You would add another emitter again at this time to deliver more water. You should avoid increasing the minutes to give it more water. Two drip emitters will not be enough for a tree this size With that in mind, I would estimate that after three years in the ground your tree should receive about 10 to 15 gallons each time you water if planted from a 15 gallon container. I can’t give you that estimate in minutes because I don’t know how much water the plant is getting in one of its minutes. You should determine how much water is being delivered to the tree. I’m not sure if you’re using drip or not but many emitters state the number of gallons per hour that it is delivering or they are color-coded. Add all these gallons together and divide by the fraction of the hour you are watering; 15 minutes you would divide by 4, 30 minutes divide by two. Do not water landscape trees and shrubs daily. This time of year once a week should be adequate. You can fertilize the tree yourself. Place some fertilizer underneath each emitter or use fertilizer stakes such as Jobes next to each emitter. Jobes tree spikes If you are watering in a basin around the tree, sprinkle fertilizer in the basin and water it in and save yourself some money. Don’t put fertilize closer than a foot from the trunk.

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Don’t Give Up on Petunias Because They Don’t Flower

Leave a Comment / Tobacco budworm, what causes petunias to stop flowering, why is my Petunia no longer blooming / xtremehorticulture

Q. I had two planters of petunias that stopped blooming and the leaves had lots of little holes. You told me that Tobacco Budworm was at fault and suggested applying Dipel or Thuricide. After several applications we had lots of blooms on the petunias. At the end of this growing season should we replace all of the potting soil in the planters with new soil in the spring? Many thanks! A. This insect can survive here through the winter in the soil. If these are potted plants then you can replace the soil but cultivating the soil several days before planting will help to expose them to birds. I would watch for this problem in the future. These insects have wings in their adult form so they will fly into your flower bed from the neighbors. The two things to look for are the holes in the leaves and those little black specks which is budworm poop. Next year in May or June start looking for that on your petunias and other susceptible flowers. I would not give up on petunias and Nicotiana just because of budworm. Put down a couple of protective sprays of Bt, Spinosad or any synthetic pyrethrin spray in April and May. The fact that you put down Bt (Dipel or Thuricide) and had a reduction in the past problem tells me that it is working for you. Next year switch to Spinosad. The year after that use a permethrin spray. The year after that switch back to Bt. Keep rotating your pesticides.

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Desert Greenhouses Should Be Tall and Shaded

1 Comment / construction of a home greenhouse, do greenhouses work in the desert, How to make a greenhouse / xtremehorticulture

Q. We would like to grow vegetables year-round for ourselves and family unless it is too expensive. We have power (110) available and plan to do as much construction ourselves as possible. We were thinking of constructing the perimeter with a 3 foot high block wall and then enclosing the top with some type of metal hoop structure with a translucent skin. Inside the greenhouse, the floor plan would be 3′ wide and 3′ high raised planters around the perimeter, and a 3×3 down the middle. We are getting too old to be on our knees. We have water available on a timer. We aren’t sure about the hoop structure or the HVAC. What do you think? A. I am hoping you are already good vegetable gardeners. Jumping into greenhouse production without being a good gardener will result in failure. I would recommend that you don’t even attempt it unless you have solid vegetable growing experience already. Temperatures in small hobby greenhouses are very difficult to manage properly. Greenhouses in the hot desert should be as tall as possible to get the heat off of the crop. If you are hoping to save money by constructing a greenhouse and growing your own vegetables, you won’t. Those vegetables will be expensive. On the other hand, they could be better quality vegetables if grown correctly. The reason I say could is because you can get some very good quality vegetables in many of the grocery markets at different times of the year. I personally believe that you should try heated hoop houses first before you invest into a greenhouse. Inexpensive hoop houses will help you understand the management practices you will need to adopt to make growing vegetables under protected culture a reality in the desert. Shade is important in the summertime in desert greenhouses. Hoop houses allow you to start your growing season 6 to 8 weeks earlier in the spring and extend this season 6 to 8 weeks in the fall. Doing this allows you to grow vegetables all year long here. In fact, you can grow vegetables all year round here without any hoop house. You will not be able to grow any vegetable you want at any time of the year but you can grow vegetables in their appropriate season. There are a lot of things that are going through my mind that you could try if you want to build your own greenhouse. It is not going to be cheap. In the hot desert you want these houses to be as tall as possible to get the heat up and off of the crops instead of captured under the canopy or roof. These houses have to have very good ventilation. They need to have at least one air exchange every minute so you need excellent ventilation. This is usually done with exhaust fans that are sized so that you get the correct air movement and ventilation in the greenhouse. There are two exposures that I think will work for you depending on the type of greenhouse. The first is an east facing greenhouse that receives protection from late afternoon Sun in the summer months. The house is oriented North and South. This exposure would require a minimum of six hours of full sunlight during the summer months. In the winter months it is best to get as much sun as possible. Hoop houses like this one covered in shade cloth can be a valuable ally for quality desert vegetable growing. You could keep it cool enough in the summer months using a swamp cooler and a ventilation fan or fans pulling the cool air through the house. An alternative for an east facing house is to construct the North end wall as a very large evaporative pad with ventilation fans in the South end wall. The west wall would be a solid, insulated wall. The Chinese style greenhouse is a south facing greenhouse with the North wall a solid block wall that can capture heat during the winter months. Extending from the top of the North wall is a shade cloth of about 30 or 40% shade that shades the vegetables during the summer when the sun is directly overhead. Plastic covered houses in Egypt. In the winter months when the sun is at a lower angle the sun will shine directly on the vegetables. This greenhouse usually has a solid wall about 3 feet high along the east, south and west sides. Hoops or lumber is used to construct the supports for the greenhouse clear “skin” on top of this low wall. Ventilation is from the East to the West wall. The house is oriented east and west.how to make a greenhouse, I hope this helps you a little bit. Perhaps I should put together some classes but like I said, it will be expensive to build these. My recommendation is to start with the hoop houses.

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Major Cause for Gardenia Death

Leave a Comment / Gardenia losing leaves, Gardenia with Brown leaves, what causes gardenias to die / xtremehorticulture

Q. I have a gardenia that is approximately four years old. It has bloomed yearly and was doing great until all of a sudden, literally, about 75% of the leaves turned yellow and fell off. It is on the patio, outside, where his always been in the shade and I water daily. Gardenia with leaves yellowing. A. I think your gardenia has developed root rot. This is fairly common in guarding. The symptoms of root rot is yellowing leaves and leaf drop. Frequently the plant dies a relatively slow death unless it’s in the heat, then it could be rapid. You didn’t come out and say it but it sounds like the plant is in a container. When we grow in containers, the soil organic matter part of it (this is the part that helps keeps the soil loose and gives good air exchange to the roots) begins disappearing at a steady rate. It will be in a critically short supply by the third year. As soil organic matter disappears over time, the open spaces that help with drainage and air exchange, diminishes. Gardenia with dark green leaves, a sign of health. At the very beginning, a container soil may contain as much as 50% of its volume in pore space. Over three years this pore space could drop to only 20 or 15%. Basically the soil collapses, losing its pore space. Collapsing soil becomes more dense, water drains through it more slowly, the soil stays wet longer, salts may begin to accumulate and the roots begin to suffocate. Soil diseases attack the weakened roots, roots begin to die, leaves begin to yellow and drop from plant. This is why soils in containers need to be renewed every two to three years depending on the type of plant. Since gardenia is very susceptible to rots and grows much better in aerated soils, I would not go longer than every other year. If the Gardenia is not too far along in leaf yellowing and leaf drop, you might be able to save it. Go to your favorite nursery or garden center and purchase a good quality container soil, enough to refill the container. When you are there, purchase a chemical fungicide containing Subdue. Subdue fungicide does a good job in controlling several of the root rot disease organisms. Applying a fungicide alone will not solve the problem so you must repot the plant as well. The plant can be put back in the same container if it is sanitized on the inside or use a different clean container. Remove the plant from the container during the cool temperatures of the morning and out of direct sunlight. Once the plant has been removed from the container, repot it quickly because the tiny feeder roots die quickly when exposed to the air. Place the plant on a clean surface and gently wash the soil away from the plant roots. Thoroughly clean the container and sanitize the inside of it with a 200 ppm solution of bleach and water. This would be about on tablespoon of bleach in one gallon of water. Rinse the container and wipe out the excess with a clean rag or towel. Let it air dry in the sun for a few minutes to let the chlorine disappear. Or you can use a clean, fresh container. Once you have carefully removed as much soil from the roots as possible, repot the plant and use tap water to resettle the soil around the roots and remove air pockets. You will apply the subdue fungicide according to the label and water it into the soil of the repotted plant as a soil drench. Follow label directions. Fertilize the plant as you would normally and watch for new growth to come from leafless stems that are still alive. Once every two years remove about one third of the soil from the container and replenish the container soil.

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Plunge Fresh Fruit into Icy Water after Harvest

Leave a Comment / Field heat, how to harvest fruit, how to harvest plums, increasing the shelf life of fruit / xtremehorticulture

Q. I did what you told me to do to ripen the plums and it worked but they were mostly still very tart. Why did you tell me to put them in cold water after I picked them? A. When you harvest fruit in the heat of the summer, the fruit will have a lot of excessive warmth or heat. The heat is from the environment as well as the fruit’s respiration. We call this heat, field heat. This heat can be very destructive to fruit harvested in the field and cause poor keeping quality. For this reason we want to remove this heat from the fruit as quickly as possible very soon after harvesting. One way to do this is just plunge the fruit into icy water for a few minutes and get it closer to room temperature. After it cools to room temperature, you can let it continue to ripen at room temperature.

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Olive, Vitex or Crape Myrtle. Which is best?

Leave a Comment / chaste tree, compare trees, contrast trees, crape myrtle, crepe myrtle, european olive, monks pepper, pros and cons, tree selection, which tree is best / xtremehorticulture

Q. You helped me out a couple of years ago when I had questions about growing tree roses. Now I would like your opinion on some tree varieties. This fall I would like to replace a couple of sumacs in my back yard. I really like three trees: olive, chaste and crape myrtle but I can’t find anything online that compares these three trees. Do you have a favorite? Can you give me some pro’s and con’s compared to each other? A. These three trees are dramatically different from one another in many ways, are used for different purposes in the landscape and have different watering requirements. All three will work here, Crape Myrtle being more difficult to manage than Olive or Vitex. Crape myrtle growing in desert soil Comparing all three trees, crape Myrtle provides the most year around beauty in the landscape. All of them are relatively slow in getting some size so you might shop for some larger trees if you want some instant impact after their planting. Olive is the only evergreen tree in the group. I would classify European olive as primarily a 25 to 35 ft. shade tree that can take tremendous abuse. This tree will rebound if pruned badly so it is a relatively safe tree to have if you contract blow and go landscapers to do your property. The other two trees will not rebound like an olive if they are pruned badly. In my opinion, Crape Myrtle might be ruined. If you need something that creates shade, screens, or privacy all year round and is easy on water use, then you might consider olive. As you know we can only plant so-called fruitless olive in Clark County, Nevada. So you will be restricted to either Swan Hill or Wilsonii. However, you can add Monrovia nursery’s Majestic Beauty (Monher variety) to the fruitless list as well. I have had numerous complaints about fruitless varieties producing fruit as they get older. It is believed this happens because these are grafted varieties and the top is lost at the bud union. The rootstock continues growing which is a fruitful olive and the tree becomes an olive tree that produces fruit with a fruitless tag. Others believe tags are mixed up in the nursery. Crape myrtle trunk, young tree In any case, don’t expect your fruitless olive to be totally fruitless. If you need this tree to be totally fruitless, pick something else. Olive is relatively pest free. It requires minimal maintenance. Both olive and Crape Myrtle get to be similar in mature size, around 25 to 40 feet. It will do well in a lawn or a rock mulch desert landscape. You would use this tree if you want a rock solid landscape tree that can handle a lot of abuse. Crape Myrtle can also be spelled Crêpe Myrtle. In other parts of the country they come in a wide range of mature sizes ranging from 3 feet tall to 25 feet tall. Their flower color ranges from white to pink’s, to reds, two lavenders. Selection in Las Vegas will be much more limited but shop around. I have been surprised seeing selections in Lowe’s and Home Depot. It is flat-out gorgeous tree if cared for properly. That is the key. European olive It is what we call a specimen tree, a showstopper when in bloom and even in the winter when it is leafless. It is meant to be a focal point for landscape. A larger tree will provide shade as it gets older but it is really meant to stimulate conversations and to draw your eye because it says, “Look at me!” when it is blooming. Olive flowers Crape Myrtle is a beautiful tree when it is blooming but I would argue that the texture of its trunk and its silhouette in winter rivals its flowers. The exfoliating character of the trunk is gorgeous up close. If pruned properly its winter silhouette without leaves can be beautiful as well. The combination of flowers and uniqueness of its trunk and winter silhouette provides year around beauty. This tree needs to be pruned professionally by certified arborists or by a knowledgeable homeowner. You do not want blow and go landscapers to touch this tree! It will require special fertilizer applications including iron. It will do best with wood surface mulches but it can grow in desert landscapes as well. In desert/rock landscapes crape Myrtle will require more care to keep it looking good over the years. There are dwarf varieties 3 to 6 feet tall, semi-dwarf varieties 7 or 8 feet tall, all the way up to full size which is about 25 feet in height. Most sold here are full-sized but shop around and you may get lucky finding other types. Locally I have had complaints that trees were mislabeled and customers received a different flower color from what they expected. The other complaint was how they were planted. Be very careful of companies that advertise free planting. This tree needs to have plenty of soil amendment go into the planting hole at the time of planting. When planting is free, the holes are dug way too small, very little soil amendment is used and the type of soil amendment used his lousy. If I were buying a boxed, specimen Crape Myrtle I would want to see that the flower color matched the nursery tag and I would have the hole dug to my specifications by an outside party and buy my soil amendment separately from the plant purchase. I would be placing this near a patio, a sitting area outside the master bedroom, near a place for people congregate in the backyard, or where you want people to look in the front yard. It has few pest problems. Vitex or Chaste tree is a smaller tree than the other two. None of the three trees are trees that originate from deserts. However, all three will perform in a desert landscape reasonably

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Don’t Expect Third Crop from Figs

Leave a Comment / forcing figs to fruit, how to get third crop, How to produce figs / xtremehorticulture

Don’t expect to get that third crop of figs from your fig tree this fall in our Mojave Desert climate. In the Las Vegas climate of the Mojave Desert figs just do not have enough time to produce that third crop. If we had extended warm weather through November we could get that third crop. The third crop will try to form but it sits there as young immature figs because the weather is cooling down to rapidly. There is no way to get that third crop without global warming or building some type of greenhouse enclosure around the tree. Third crop of figs that didn’t make it from a previous reader

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Problem With Chitalpa after Deep Root Feeding

12 Comments / applying fertilizer to trees, damage from deep root fertilizing, fertilization, fertilizer, how to fertilize large trees / xtremehorticulture

Q. We are having a major problem with one of our two chitalpa trees after they were fertilized. We were told by professionals that these are desert trees and don’t require a lot of water and the watering schedule has not changed for 2-1/2 years. They are on drip irrigation with each tree receiving 5 gallons of water a day scheduled at 2 AM, 6 AM and 10 PM. We had a tree service company do a deep root feeding on May 14th because one tree looked sickly while the other one was healthy. After fertilizer was applied the healthy one now has leaves that are brown, curled up and falling off. The tree service came back out and suggested to water the tree for an hour for two consecutive days just in case the fertilizer put the tree into a shock. We did that with no change in the trees except for new shoots growing from the trunk of the damaged one. The tree service doesn’t know the problem. Should we plan on replacing this tree in the near future or will it come back next year? Chitalpa not the readers Chitalpa not the readers Chitalpa not the readers A. Desert trees need water just like regular trees but their main claim to fame is that they need irrigations less often. Let’s explore what happened. First of all, 5 gallons of water a day is not enough water unless they are very small trees, perhaps no more than 5 feet tall. Secondly, there is no reason to apply the water at three different times when using drip emitters. Drip emitters apply water very slowly so the entire amount of water can be applied at one time with no problems. I think you may have been a bit misled when you purchased these trees. Many people, including professionals, do not understand the relationship between the water use of desert trees and the level of acceptability these trees have when different amounts of water is applied. Chitalpa with limb dieback, probably watering issue, not the readers Just because trees are so-called desert trees does not mean that they can get by with very little water. Chitalpa is a desert-adapted tree, not really a true desert tree like some of the acacias and palo verdes. I do think your damaged tree resulted from the fertilizer application to the soil. I don’t think there was enough water present in the soil to dilute the fertilizer enough to keep the roots from getting damaged after the application. Secondly, I believe the soil water taken up by the roots was so high in fertilizer salts that the leaves were damaged and the severely damaged ones fell from the tree. What can you do? Flood the area under the tree with water once a week for the next three weeks. After this, go back to normal irrigations using your irrigation system. I would look closely at the possibility that you may not be applying enough water during an irrigation. More about deep root fertilizer applications If you suspect this might be the case, either increase the number of minutes so that more water is applied or add more drip emitters under the canopy if you suspect there are not enough. You will increase the amount of water either way. The key consideration is whether you are applying enough water under the entire canopy or not. If you suspect you are not, then the only solution is to add more emitters. What will happen to the tree? Because of leaf drop you may have some branch die back and lose some limbs. Let the tree continue to grow this summer and fall and don’t do any pruning until this winter. This winter see if you can do some corrective pruning to improve the shape of the tree. If the tree has been to severely damaged due to die back, then you might consider replacing it. I don’t think you can make that determination for another month or two.

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Plant Lantana While Soil Still Warm

Leave a Comment / fall planting, fall planting of lantana, how to plant lantana, when to plant lantana / xtremehorticulture

Q. Is it better to plant lantanas now or wait until Spring? Lantana with spring growth A. Now for most of November is a great time if you can find them. Make sure to amend the soil with good compost and water thoroughly each day for several days in a row and then turn it over to your drip system. Before they start growing next spring, cut them back to about an inch and a half above the soil, fertilize them and give them a good drink.

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Precautions When Planting Peach After Borers

Leave a Comment / are borers in the soil, can i plant a tree after borers, sterilizing soil for planting / xtremehorticulture

Q. You recently identified that my peach trees had borers in them. I found the oval larval holes under the loose bark. Can I plant a new peach tree where I removed the afflicted tree? If so, are there any preventive measures I should take? A. There is no problem planting in the same hole. This insect burrows into the tree, not the soil. However, make sure you whitewash the next tree with either tree whitewash made from lime or dilute white latex paint, or nearly white latex paint, not an oil-based paint, with about the same amount of water and apply it to the trunk and main scaffold limbs. Prune the tree so the canopy shades as much of the trunk and scaffold limbs as possible. Make sure the tree receives adequate water and if you can apply 3 to 4 inches of a woodchip surface mulch the tree will perform better and have less stress. Peach tree with whitewash and mulch Make sure you keep surface mulches a safe distance from the trunk so it does not cause it to rot from excess moisture. That has a known history of good performance in our desert. You can go to my blog, extremehorticulture of the desert, and search for recommended fruit tree varieties if you don’t have one in mind. This borer can fly and comes in from other infested trees including many landscape trees and shrubs in the area. Sunburn or sunscald is the main culprit so providing shade on the trunk and lower limbs and giving it protection from whitewash helps reduce sunburn. Good luck.

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