Xtremehorticulture

Xtremehorticulture of the Desert

What Vegetables Can I Plant in March?

2 Comments / What vegetables can I plant in March /

Here is a list of vegetables you can plant in March in the Las Vegas Valley. The Las Vegas Valley is around 2000 foot elevation (650 meters). Lower elevations can start earlier than this. Higher elevations can delay planting a bit. March Bush beans (s), broccoli (s,T), brussels sprouts (T), cabbage (T), carrots (s), sweet corn (s), eggplant late in the month (T), green beans (s), pole beans (s), kale (s), kohlrabi (s), lettuce (s), onion sets, onions (T), peppers late in the month (T), potatoes, radishes (s), spinach (s), Swiss chard (s), tomato late in the month (T), turnip (s) T= tramsplants are best s= cam be started by seed

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You Can Still Prune after New Growth Starts

Leave a Comment / How late can I prune fruit trees, when to prune fruit trees /

Q. Took your recommendation and planted a Dapple Dandy pluot and Santa Rosa plum in the same hole about 18 inches apart. New growth has already started to appear. What I’d like to do now is cut and lower the height of the Santa Rosa plum to the same height as the pluot. Is it too late to do that? Pluot and plum planted in the same hole. Santa Rosa plum is one of the best pollinators for Pluots. The fruit trees are whitewashed to help prevent sunburn. A. No, it is not too late to prune. People are mistaken when they think the only time to prune is during the winter months and when new growth appears, it is no longer permitted. This is a not correct.             One of my professors used to say, “The best time to prune is when the pruners are sharp.” I still agree with him. However I would alter that by adding, “as long as it is a hand pruners.” If you are removing large diameter wood using a saw or loppers timing is more critical.             In short, go ahead and lower the height of that pluot. Make sure you whitewash the upper surfaces of any exposed limbs to reduce sunburn unexposed branches. I will talk about summer pruning next month. I will post more about this topic on my blog.

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Be Careful with Fertilizers for Tomatoes

Leave a Comment / How to fertilize tomatoes, what fertilizer is best for tomatoes, what should I use to fertilize tomatoes /

Q. I was reading an older article from Linn Mills about foliar fertilizing tomatoes. Linn was saying to spray tomato plants with phosphorous. I read an organic article in which they use fish-seaweed extract in your opinion which is better to use? High phosphorus fertilizers do not cause all vine and no fruit A. Great advice from Linn! You want to give tomatoes a complete fertilizer at the time of planting. You can use organic sources or conventional fertilizers. It will not make much difference to the plant. These can be applied to the soil or to the plant leaves if they are a liquid. After an initial application of a fertilizer, phosphorus should be in abundance, not nitrogen, with further applications. The problem with organic sources like compost added to the soil at the time of planting is that the fertilizers or nutrients they contain last so long. This is because the nitrogen in the compost is released slowly over a period of several months. This is not true of organic foliar sprays like seaweed extracts. An overabundance of compost added to the soil will cause tomatoes to produce a lot of vine and delay flowering. This is not necessarily true of their close cousins, peppers and eggplant. If flowering is delayed in tomato and begins during the heat of the summer, it can result in little to no fruit production. Example of a high phosphorus foliar fertilizer to stimulate flowers and fruit Inexpensive conventional fertilizers (farm fertilizers) release its nutrients quickly. One big shot is released during the first few irrigations and the amount of fertilizer available to the plant diminishes quickly after that. These quick release or conventional fertilizers, at least the nitrogen component, lasts four to six weeks and 80% of it is gone. Quick release fertilizers, applied at planting time, are perfect for tomato growth and fruit production. Foliar fertilizers, fertilizers applied as a liquid to the leaves and stems, act very similarly to quick release fertilizers applied to the soil. Liquid fertilizers applied to leaves last a very short time; 2 to 3 weeks. Foliar fertilizers need to be applied more often than fertilizers applied to the soils. Foliar fertilizers should always contain a wetting agent to help that fertilizer gain entry inside the plant. We want tomato plants to gain size quickly for about four weeks before they set fruit. If nitrogen is released in large amounts after that time, it will likely cause a delay in flowering and put on leaf and stem growth instead. Example of a 1:1:1 fertilizer If you are foliar feeding, you should have at least two different types of foliar fertilizers, maybe even three. The two which are most important are a high nitrogen content (highest first number) fertilizer and the second is a foliar fertilizer with high phosphorus content (highest second number). If you get a third one then make it a fertilizer in a 1:1:1 ratio of nitrogen, phosphorus and potassium. Whenever possible make sure the third number, potassium, is also high in all three fertilizers or make sure it is applied to the soil and available to plants.

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Help Save My Photinia from Dying

Leave a Comment / iron chlorosis, leaf scorch, leaf yellowing /

Q. Our red tip photinia appears to be dying. It is 8 years old and receives full sun. The leaves are turning brown and dry.  Is there a disease causing this or is it the very hot weather we have experienced this summer?  We fertilize and  apply iron regularly. Photinia with iron problems and soils with lack of organic matter A. The usual problem with Photinia occurs when their planted in desert landscaping with rock mulch covering the surface of the soil. They are planted with some soil amendment in the planting hole which disappears in two or three years. Sometime during the fourth and fifth year Photinia begins to develop yellow leaves. Photinia with the beginning of the decline These yellow leaves become a brighter yellow and begin to scorch around the edges. If this problem is not fixed, Photinia gets worse and we see die back of the stems and the canopy of the plant opens up and looks very sparse. The problem is the rock mulch for this plant. They do not like it. They like organic soils, not soils covered in rock. You have two options. Pull the rock mulch back and add compost to the soil around each of the Photinia about an inch deep and scratch it into the surface. Next cover the area with wood mulch, not rock mulch. Add iron fertilizer and a regular fertilizer to the plants. Water them in thoroughly with a hose. Cut the Photinia back close to the ground and let it regrow. Hopefully this will get them off to a good start this spring. Continual additions of compost every two years will help this plant stay healthy. The second option is to dig and remove these plants and start all over. Make sure the soil they are planted in as 50% compost mixed with it. Cover the soil with wood mulch and grow them out. Fertilize once a year in January with the commercial fertilizer for trees and shrubs and make sure you add an iron fertilizer at the same time.

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Starting Texas Mountain Laurel from Seed

Leave a Comment / hard seed coat, legume, seed germination /

Q. I harvested some Texas Mountain Laura. Can I expect them to grow if I plant them in garden soil? Should I remove the outer shell first? Texas mountain Laurel dried seed pods A. Texas mountain Laurel can be started or propagated from seed but there is at least one major hurdle you must overcome. This hurdle is the very hard coat around the seed, not the pod. The seed is best harvested from pods that have not fully matured. If possible harvest the seed from pods that have not yet turned brown but give you a clear indication that there is a seed which has fully formed. Texas mountain Laurel For seeds to germinate they must absorb water, be at the right stage of development, have warm temperatures and air. This very hard seed coat does not permit water to enter the seed and begin the germination process.  To my knowledge, this seed does not have to be stored in cold temperatures prior to starting them from seed. Some seeds from temperate climates have to go through a simulated winter in the refrigerator before you plant them or they will not germinate.  This seed does not seem to need this. However, to be on the safe side take half of your seed and give them an 8 week cold treatment in the fridge and take the other half with no cold treatment and see what happens. Give them a cold treatment before you damage the seed coat. Damaging the seed coat without damaging the seed permits water to enter and start the germination process. If the damage to the seed coat is too deep, the seed may die.            The easiest way to damage the seed coat safely is to use a file or sandpaper and scratch or nick the seed coat deep enough so this barrier is breached but not deep enough to damage the seed itself.            There will be some variation in these plants because they are propagated sexually, that is by seed. When these seedlings first come out and reach about 1 foot in height you can begin to discard plants that don’t have the size or shape that you desire. This is called “roguing” out the seedlings. Here is a good website to look at. http://uts.cc.utexas.edu/~harms/MtL-seed.html This website seems to say it needs a cold treatment http://homeguides.sfgate.com/grow-mountain-laurels-seed-25353.html

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When to Plant Tomatoes, Peppers and Eggplant?

Leave a Comment / Uncategorized /

Traditionally, by the middle of March at around the 2000 foot elevation in southern Nevada, we will have a 90% chance that there will be no more frost. This is normally the date we use for planting warm season vegetables. Strong and vigorous tomato transplant You can usually sneak them in a little earlier if you watch the weather forecasts or give them some protection. Tomatoes are warm season crops and they can suffer from chilling injury. This is damage to the plants if temperatures drop close to the same temperature in your refrigerator. Even a bit higher than this. Hot microclimates in the yard can support please vegetables earlier than the middle of March. So if they are going in a spot that is West or South facing, you can put them in earlier. Watch for temperatures below 50° F. If temperatures are going to drop this low, there is a potential for chilling injury. You can use some hot caps and cover them at night when the sun goes down. White woven crop cover rolled back showing the differencein plant growth a crop cover can make in spring You can use a crop cover and lay it over the top of them. These crop covers will give you an extra 5° F over the lowest temperature during the night. You can throw a light blanket over them if you push in some short stakes to keep the blanket from crushing plants. Or you can buy the plants and leave them in their containers. Put them outside during the day and move them indoors at night. This way you can delay planting them if you think there might be some low temperatures coming.

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Strawberry Tree Needs Extra Care in the Desert

Leave a Comment / leaf drop in strawberry tree, Strawberry tree leaves Brown, Why are my leaves turning Brown /

Q. I have a strawberry tree that is probably getting too much sun. The tips of the leaves are very discolored. Is there anything I can do to help it? A. Strawberry tree is native to Western Europe and the Mediterranean region.  Its leaves tend to yellow because of micronutrient fertilizer problems, cold temperatures and intense sunlight. Leaves also tend to scorch on the tips in very hot locations with intense sunlight. They do not perform well in rock mulch in south or western exposures. Getting this plant closer to optimum health helps it tolerate stresses caused by extreme soil and environmental conditions. Soil improvement and wood surface mulch will help this plant a lot. This plant should not be in rock mulch. Rock mulches radiate a lot of heat during the summer and add nothing back to the soil. If this plant is in rock mulch, I would pull the rock back a couple of feet and apply an inch or two of compost. After lightly incorporating the compost into the upper soil surface, I would cover the exposed area with about 3 to 4 inches of wood chips. The combination of compost and decomposing wood chips will help to rebuild the soil around the roots. Rebuilding the soil around the roots improves the biological activity of the soil and overall plant health. From your picture, the foliage otherwise looks healthy except for its scorched leaf tips. I would guess it is getting adequate amounts of fertilizer. Applying fertilizers regularly to desert soils is frequently not enough to provide a plant with optimum health. Be sure to add an iron chelate such as EDDHA in a spring application of fertilizer once a year. The combination of the right kind of fertilizer, soil improvement and wood surface mulch will bring this plant closer to optimum health and better tolerance for hot locations.

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When Should I Prune My Vitex Tree?

Leave a Comment / chaste tree, flowering in vitex, how to prune vitex, monks pepper, when does vitex produce flowers /

Q. When should Vitex tree be trimmed and how much should be cut? Vitex in its winter form A. Vitex blooms in early summer through late June or July. If this plant is pruned with a hedge shears you will likely affect how it blooms this summer. Larger vitex in late June Vitex with flowers in June Any pruning done now should selectively remove entire branches back to a crotch. This is a pruning technique called “drop-crotching”. This technique reduces the size of a plant while still retaining its natural form. Drop-crotching avoids plant injuries due to “topping”. Vitex in bloom in May Limbs that add height or size are removed at the juncture with a branch of smaller size. This type of limb removal maintains terminal buds at a lower height, retains flowers and maintains the architecture of the plant. The opposite of drop-crotching is topping, or shearing the plant at a desired height or size. We do not want to do that to most trees. After reducing the size of Vitex we would remove any crossed branches or broken branches and shape the tree to maintain its symmetry.

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Can I Save My Wind Damaged Tree?

Leave a Comment / how to repair wind damage to large trees, repairing split crotch /

A. yes, both branches can be saved or you can remove one of the larger branches but I know removing a large part of the canopy will make it look ugly. Repairing this type of damage is best left for professional arborists.  If you want to tackle this yourself or hire someone to do it under your supervision, then this would be the procedure you would follow. Pay particular attention in getting the right supplies for this type of job.  Any permanent steel that enters and stays inside the tree should be stainless. Any steel outside of the tree that would be resistant to the environment would either be stainless or galvanized. But it is very important to use stainless on anything in contact with wet tissue inside the tree. It is also important to make sure that the supplies you use are strong enough. Use American or Western manufactured steel products. Avoid Chinese made steel products. I have been very disappointed in the quality of some of these materials from outside the United States. I realize why they are available but these supplies have to be able to accommodate the bearing load of that tree in future years. This type of repair to a very large tree is usually beyond the abilities of most homeowners. There is also the possibility of future liability if this work is not done correctly. Having said all that, these are the basic steps that should be taken. Supplies you will need: stainless steel eye screws with a length long enough to penetrate 1/3 the diameter of the limbs galvanized, stranded wire cable with a working load limit capable of supporting the canopy (for large canopies cabling may need to be done in multiple locations) stainless steel partially threaded rod, washers and nuts Equipment you will need: chainsaw or arborists handsaw large enough for drop-crotching limbs power drill or manually operated brace wood bit long enough to drill a continuous hole through the split to accommodate the partially threaded rod 1. Reduce the load (weight) on both sides of the split by removing some of the top growth. Use a technique called drop-crotchng to remove top growth. Drop-crotching is selective removal of branches. The removal of these branches is at the “V” where the tallest branches come together with a side branch. Removal of these limbs should be just outside the “collar” of the limb to promote faster healing. Sanitize and disinfect all blades or bits used for entering the tree prior to its use. 2. Drill pilot holes for the eye screws into major limbs for securing the stranded cable. Secure eye screws into the major limbs a distance into the tree of one third the diameter of those limbs. Eye screws should be stainless steel, not galvanized or zinc plated. Large canopies may need two or more locations where eye screws are inserted and cabling is secured. 3. Secure stranded galvanized cable through eye screws and use a block and tackle, come-a-long or winch to pull these major limbs together enough so that the split visually disappears. Treat the top of the split with grafting wax to keep water from penetrating to the inside of the tree. The grafting wax is not permanent but helps keep water out of the crack until compartmentalization of the damaged area can occur. You can also use water-based asphalt sealer. 4. Drill a continuous hole through the trunk at the split. The hole should be continuous to accommodate a steel rod large enough in diameter to assist in bearing the load of the canopy. 5. Insert the stainless steel rod and secure both ends with stainless steel washers and nuts. Tighten the nuts to assist in bearing the load of the canopy. The tree will eventually engulf the steel rod, washers and nuts. You should remember to notify anyone who might remove the tree that there is a steel rod in the interior at the split. You can read more information on this and see some pictures of how this is done at: http://essmextension.tamu.edu/treecarekit/index.php/after-the-storm/tree-damage-and-hazard-assessment/repairing-storm-damaged-trees/ http://www.kbs.msu.edu/information-resources/repairing-storm-damaged-trees http://gearycountyextension.com/Hort/Stormdamagetotrees.pdf

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Black Spot and Rust Not Common in Vegas Roses

Leave a Comment / Black spot of rose, diseases of roses, rust of rose /

Q. Here’s the pic of what’s going on with my roses.  What do you think?  Black spot or rust? A.This was sent to me in July, 2014. I really didn’t see any black spot or rust in the picture. Black spot of roses have the typical “black spots” on the leaves and rust are pustules on the leaves that can be rubbed off with your fingers. Both are more common during the spring, periods of high humidity and too much shade. Usually full sunlight, drip irrigation (no overhead irrigations), watering during early morning hours, fertilizing regularly and our dry conditions seldom lend itself to either disease here. If you need to put on a preventive treatment on roses in the spring or fall, apply one of these treatments to the leaves: sulfur dust, Neem oil or compost tea. The damage looks more like spider mites, drought or lack of fertilizer. Make sure roses have an organic surface mulch applied to the top of the soil that decomposes (wood chips), use drip irrigation, water early in the morning and are fertilize during the spring and fall months. 

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