Xtremehorticulture

Xtremehorticulture of the Desert

When and How to Prune and Fertilize a Cassia

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Q. My cassia is full of beautiful yellow blooms. First year this two year old plant has done this. When do I trim it back and how far?  Type of fertilizer will it need?   The base of cassia has several strong stems coming from the base. Choose one or two of these strong stems and remove then at the base. Let it regrow from the base to rejuvinate it and let the leaves fill in from top to bottom from the strong young basal growth. A. Shrubs or other plants should be pruned soon after they flower. In spring flowering plants the flowers are produced during the late summer and fall months. Some finish maturing in the spring before they flower. But regardless, if these spring flowering shrubs are winter pruned with a hedge shears it will remove the spring flowers. If shrubs are pruned properly and not pruned with a hedge shears they then can be winter pruned. Hedge shears should be reserved for nonflowering hedges. Reach down inside the canopy, or from the outside, cut with a sharp and cleaned pruning shears about one inch above the surface of the soil and make your cut. Pick stems that are the largest or too close together. Pruning should be done with a few well-placed cuts deep inside the canopy to remove sections of the plant which are crowded, too tall or too wide. Cuts are made where two stems join together, removing the offensive stem. This results in a general thinning of the shrub removing larger diameter wood. By removing larger diameter wood, this “renews” the shrub and helps keep it young. I hope this helps.

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Center of Cassia Bush Died. What to Do?

Leave a Comment / dead center, pruning, ugly, when to prune /

Q. I have a cassia at the corner of my house to block the street view of my air conditioning unit.  The whole center section visible from the street has died.  I’m beginning to cut out the dead limbs. I check the cuts but am not seeing any green at the bark.  Is there a chance that partially cut back limbs might still produce new growth?  Or should I cut back to the main trunk?  With no center section it looks ugly. Can I hope the living branches will fill in eventually?  Dig it out and replant with a new one?  One of the cassias and what it should look like with proper care as it is getting at the Las Springs Preserve A. Yes it is possible you had some winter kill but doesn’t sound like winter kill. Winter kill is most common on new growth, such as the tips of branches, if temperatures are just below their tolerance. If temperatures a considerably below their tolerance, then you will see death also in the older, larger diameter wood.  This is what a cassia will look like armed with hedge shears, improper watering and lack of fertilizer 5 years after planting. It is odd if it is just damaging the interior wood and leaving other parts of the plant alone. Another possibility is root rot if it is watered too often or the area is flooded. This should be fairly easy to determine by pulling the top of the plant toward you and looking at the base of the plant. In cases of root rot, trees and shrubs the plant will not be securely anchored in the soil. When you pull on it the base will move around and not be firmly anchored in the soil. In healthy plants that are not winter damaged you should be able to scrape the soft outer bark with your fingernail and see green beneath it. This is not easy to see in all plants. But at least the inner bark should be cream colored or white. So I would not cut anything back at this time. If there is winter damage then the killing temperatures already “pruned” it back. If the plant or plant parts are alive they will show you where to cut after new growth emerges. When it emerges, cut a few inches below the dead part of the limb and into the strong growth, just above a bud or at a crotch (where two stems come together). If you don’t see any new growth by mid-April, then it is dead. Whether to remove it or not is really a subjective call and not one I can direct. It is your call. With an established root system it should grow back very rapidly and will fill in the spots where there is strong sunlight.

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Pink Leaves on Purple Plum Probably Iron Problem

Leave a Comment / chelate, chlorosis, EDDHA, iron 138, pink leaves, purple leaf plum /

Iron chlorosis on purple leaf plum Q. I have two red leaf plum trees both about two years old. They started the year beautifully. One continues to look normal but the other one has all of a sudden taken a turn that bothers me. The leaves are getting pale, pink instead of red and see through-ish. It is a nice full tree yet young. Is it as simple as not enough water or something else? It had a great year last year. A. It is most likely iron chlorosis. If you want to see if that is the problem try making a few liquid applications of an iron chelate to some leaves using a spray bottle to see if this turns them dark purple (I am assuming you have a purple leaf plum).             It may take four or five applications with a spray bottle to the same few leaves a couple of days apart since liquid applications to the leaves are not typically as effective as applying it to the soil. Otherwise buy some iron chelate containing the EDDHA chelate and apply it to the soil in a bucket of water and wash it in around the roots.             You should see it turn dark purple in growth that comes out AFTER you make the application to the soil. This discoloration is also possible if the tree roots are being kept too wet by watering too often or you have poor drainage.

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Asparagus Should Be Cut Below the Soil Surface

Leave a Comment / cutting asparagus, harvest asparagus, proper way, snapping asparagus, stubble /

Q. I have a raised bed (5 x 10 feet) dedicated to asparagus. The yield has been magnificent. However, the plot has gotten so overgrown with old asparagus stumps that I have had to totally remove and replace all the soil because cultivation was impossible. My question is how long can an asparagus garden last without being so impacted that it must be replaced; or, is there a way to deal with spent stumps annually to prevent this problem.   Purple passion asparagus with some rabbit damage. Rabbits love the higher sugar content of Purple Passion A. Asparagus rhizomes are normally planted about 12 inches below the soil surface. If started from seed, the seed is planted in a trench and backfilled as the plants grow so that the developing rhizomes are still at about 12 inches deep.  Asparagus crown for vegetative propagation. Selecting crowns that are male will guarantee a male crop. Spears emerge from the top where the fleshy roots come together When this is done the spears can be harvested by cutting below the soil surface with a knife so that these “stumps” don’t stay on the surface. If you harvest the spears by “snapping” them or breaking them above the soil surface then you will get these woody stumps remaining above the soil surface and they interfere with future harvesting. So, in short, if you can harvest by slicing with your knife an inch or so below the surface I think this will stop your “stump” problem. The woody part is cut off after harvesting during food preparation. The woody part should compost fairly easily. Snapping off spears will cause the spear to break just above the woody portion. Nice for the kitchen but leaves a “stubble” behind in the asparagus bed Recent research has pointed out that asparagus spears can be harvested anytime the spears are pencil diameter or larger five inches above the soil level. Smaller spears should be left to grow into fernlike growth to replenish the roots for upcoming seasons. The plant is still expanding its root storage system and excessive removal of spears weakens the plants. However, there is a market that has emerged utilizing these very thin spears. In commercial operations all spears are harvested cleaning the entire bed and spears are allowed to grow to ferns only after the harvest period. An asparagus plant will yield an average of 8 to 12 spears per year before the roots need to be replenished by letting the spears develop into ferns. Harvest spears by cutting or snapping. To cut a spear, run a knife into the soil at the base of the spear and carefully sever it. Because the spear cuts below the point where fiber develops, it becomes necessary to remove the fibrous base from the tender stalk. Most homeowners and some small scale growers prefer to snap the spears. This eliminates any woody growth on the harvested spears. This does however leave a “stubble” on the surface that can make harvesting more difficult.  To snap a spear, grasp it near the base and bend it toward the ground. The spear breaks at the lowest point where it is free of fiber. Stalk diameter is not a good indicator of proper maturity and associated tenderness. Hydrocooling, or plunging freshly harvested spears into cool, clean water is strongly recommended. Commercially, asparagus is graded by class (US Number One and US Number Two which are based on straightness and head compactness) and by diameter 5 inches from the tip (see table) according to USDA standards for canning asparagus.

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Stems of Beans Devoured at the Base

Leave a Comment / cutworm, dead, dying beans, organic, preventing, stunted beans /

 Beans planted in cool soils can get collar rot or get devoured by cutworms Q. I found a couple of beans in my garden that have been devoured at the base. Could it be some sort of soil born larva or possibly a virus?  Any ideas would be helpful. I did find one small white worm about a half of a centimeter long near the root about an inch away.    A. It could be a couple of things. First, with cool weather and cool soils it might be collar rot disease that rots the stem at soil level. This will happen if you plant beans too early in cold soils. Some varieties of beans are more susceptible to this than others. Most likely cutworm damage             The first indicator is that some plants appear stunted and grow poorly.  I usually end up removing these plants and hope the weather warms up.              The other problem can be cutworms.  You should be spraying or dusting the soil surface around these plants with either Dipel or Thuricide, an organic pesticide.  This is the time of year you should be doing that anyway for a variety of pests in the vegetable garden.

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Poisonous Plants: Dose Makes the Poison

Leave a Comment / euphorbia, gopher plant, latex sap, poisonous plants, white milky sap /

Q. I have a volunteer gopher plant in my front yard that I nurtured into a bush.  I noticed that something is eating its leaves.  We have a great deal of rabbits in our area. Can it be rabbits?  I thought that the Gopher plant was poisonous even to rabbits. What does gopher plant look like? A. I assume we are thinking of the same plant. It is a euphorbia with white latex sap coming from a damaged stem, similar to the white sap you see in poinsettia which is also a euphorbia. We tend to react to poisonous plants with fear but there are degrees of toxicity when we call something poisonous.             I watched a professor of mine in floriculture on television take a poinsettia leaf and eat it. He didn’t die or even get sick. He was demonstrating that the plant is toxic but it is the “dose that makes the poison”. If he had eaten many leaves the story would be different. Even table salt is poisonous if we eat enough of it.             So it is possible for an animal to eat “poisonous” plants and survive. I have heard that some livestock will eat gopher plant in the range with no ill effects. They just don’t eat a lot of it and only when browsing is poor. Just like us, animals like to eat things that taste good.

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Hybrid Bermudagrass Lawn Needs the Bumps Gone

Leave a Comment / aerate, dethatch, mowing bermudagrass, topdress grass, warm season grass /

Q. My hybrid bermudagrass lawn is flat and 30’x40′, yet it seems bumpy when I mow. Can I get it as flat and smooth as a putting green? Should I top dress with sand or something else? If so, what and where do I buy the material, and how do I spread it? I do not overseed in the winter, thus it’s dormant now.  Hybrid bermudagrass makes a beautiful soil cover but does require work to keep it like this   A. You can do a lot of damage to hybrid Bermuda and it will come back but you should do this when it gets hot, not now. You can level it by taking the high spots out with a straight-nosed shovel, you can fill in low spots with soil (not sand, but something similar to the soil you have now). Once you get these highs and low spots rectified, then this putting green (if that is what you want to do with it) will never have the same type of ball roll as a putting green because it is not built the same way. The best putting greens are constructed along very specific engineering specifics called the USGA Greens Section constructions specifications. http://www.usga.org/Content.aspx?id=26124 In golf course terminology you have what is called a “push-up green”, one that is made inexpensively from the local soils. These work just fine but will not give you the “feel” of the Augusta National.  Aerator for turfgrass. Sorry but I dont remember where I got this years ago. If you aerate lawns in LV, let me know. Once you have your area level you should then start to aerate, fertilize and topdress your green on a regular basis. Topdressing can be done by hand with a shove with a little practice at “throwing” it. I would look at sourcing stuff like this from sand and gravel company. Sand is used a lot because it is smaller and won’t interfere with ball roll and it is inexpensive. For professionals they would select sand similar to the sand used for constructing it. If you don’t have one, you will need a greens-type mower (usually around $600or so for the inexpensive type or frequently you can find one used from people who have converted to desert landscaping). But this will be a reel-type mower, not the rotary type. Greens are mowed at about 3/8 inch or thereabouts (bragging rights among superintendents is “how low you can go” with some at ¼ inch). These types of heights mean mowing daily in the summer months. If you let it go and mow it after a week you will not have the same quality. Mowing frequently makes the grass “tight” and helps keep weeds out as well.  Thatch is not just the light brown stuff, its the dark brown peat moss stuff below it. It is mostly dead stems, not leaf blades This climate can produce very high quality hybrid bermudagrass. It is similar to Tucson. I would rule out the climate as a problem. If it is flatter than this, then you should fill in the lower spots with soil similar to the soil in the lawn. I would not use pure sand to fill in these low spots. Bermudagrass will start to have an inferior look if you don’t dethatch the lawn. An advantage of overseeding bermudagrass in the fall is that this process requires dethatching or opening up the turf for better soil and seed contact to improve germination. If the area is small, a hand dethatcher is adequate and gives a great upper body workout. You would overseed sometime between mid-September and mid-October in our climate. Use high quality perennial ryegrass, not annual rye if you want a high quality winter lawn. Seeding rates are high if you plan on a greens height cut in the winter.  I would use something around 15 pounds of seed per thousand square feet. When you mow close, the grass plants need to be closer together so you have to use a higher seeding rate than it says on the bag. Aerating is important but if you do not dethatch bermudagrass you will have problems with color, texture and just plain looks of the grass. If you don’t overseed in the fall then you should dethatch it, but earlier so it has a chance to recover and fill in before cold weather hits. I would dethatch any time it is actively growing fast. Bermudagrass can handle that kind of stress in the heat. Cool season grasses like tall fescue cannot and must be dethatched in the spring or fall; fall is preferable, around mid-September to mid-October. Same time as overseeding (strange how that works).

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Legumes Should Be Supplemented with Nitrogen for Optimum Results

Leave a Comment / acacia, mesquite, nitrogen fertilizer, supplement fertilizer, supplement nitrogen /

 One of the bird of the desert bird of paradise, a legume. Most legumes have characteristic flowers and leaves. Q. Do nitrogen fixers like trumpet vines and locust trees provide significant nitrogen to nearby plants?  For example the Bermuda lawn surrounding the locust or the iris and daffodils in a flower bed anchored by a trumpet vine.   A. No they don’t produce enough for our high expectations in landscapes and gardens. Nitrogen fixers (such as legumes, there are others) supply enough to help make sure they can reproduce and make seed. The objectives (if I can put it in human terms) of plants and humans are different. Plants want to survive, reproduce and out-compete with other plants for their niche. In nitrogen poor soils nitrogen fixers, like legumes, take nitrogen from the air and supplement what they can’t get from the ground. In nitrogen poor soils, legumes are fantastic competitors. In nitrogen rich soils they are not. Typical legume flower leaf and pod             The expectations of humans for the plants they care for are far greater than plant objectives. We want beauty and lushness from landscape plants and we want a good production of food from our legume crops.             The nitrogen needed to meet human expectations is far greater than the nitrogen needed to meet plant objectives. So for this reason, we need to fertilize nitrogen fixing plants with nitrogen to meet our objectives. The basic rule of thumb I use is the question, “So I want my plants to meet what they consider to be adequate (reproduction and beat out the competition) or do I want them to do more than that?” Snow pea flowers and leaves are good examples of what many legumes resemble             Most people want these plants to do far more than successfully reproduce. Some people are purists and they want that “native look” or for philosophical reasons they prefer the plant produce what it can they are happy living in the “nitrogen cycle”.  Nothing wrong with that and it meets their expectations. If you want lushness or greater production, then add extra nitrogen.             The general rule of thumb you can follow is that many nitrogen fixing plants receive only about 25%, at best, of the nitrogen they need to meet our expectations. However you can treat legumes just like any other plant and feed them extra nitrogen. Plants can be lazy. If you give them all this nitrogen, they may produce little to no nodules on the roots (the nodules contain the nitrogen fixing bacteria). Hey, its alot easier to take available nitrogen than it is to build these homes on their roots for these symbiotic bacteria that take nitrogen from the air. root nodules of legume can resemble root knot nematode infestation             We are lucky in that nitrogen fixation by legumes is far more efficient in our alkaline soils of the desert than in acid soils of high rainfall areas. So to answer your question with a short winded response, no, they will not produce enough nitrogen for surrounding plants if your landscape expectations are high. If you are a eco-purist, then maybe they will.

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Removing Sucker Growth from African Sumac

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Q. I have an African Sumac that has sprouts coming up from the roots. Besides trimming them every time they get above the soil level is there anything I can do to stop these sprouts from popping up?    Suckers coming from tree rose. These should be removed from the roots by pulling back the soil and pulling them if they are young enough. If older they should be cut off below ground. A. I think I have enough information to answer. If these are naturally occurring “sprouts” and not coming from a damaged area then I would say no. However, usually if you keep these suckers controlled as soon as you see them and remove them at the trunk, not cutting them off with a shears, the number should slow down considerably.             There are chemicals you can apply that are sprout inhibitors but I don’t think you have access to those chemicals as a consumer and not a professional. Besides, even if you did have access to them they would probably be expensive for you and a real pain to apply it. The best way to reduce the numbers is make a short term commitment to remove them as soon as you see them. Remove them directly from the trunk.             This may mean you will have to remove some soil from the trunk and cut them as close to the trunk as you can. As you see new sprouts a couple of inches long, immediately pull them from the trunk.             If you keep this up and do not let them get large before you remove them then I think you will see a reduction in numbers and easier maintenance. I wish there was a magic bullet for you but I doubt it.

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Use Plants Resistant to Nematodes

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Q. You have covered on one of your post about nematodes. Last fall, I pulled one of my cucumber plants. There were 4 plants in a row. One of the plants definitely had strange roots which I am almost positive were caused by root knot nematodes. I didn’t do any solarization because it was cold during the time and I have read that it is best to do it during the hottest months. Are these nematodes harmful to humans and my dog? Will it give me a disease or worm if I touched the soil? Swelling bumps on roots is root knot nematode infestation You have covered that the only other way to fix this completely is through fumigation–which I can’t really do since I only do organic gardening. Can I at least plant any other vegetables in the same raised bed, or will it cause me any ill effects after I eat the fruit/veggies that it bears? I was also thinking of maybe removing the soil from the raised bed and move them to the big pots where I will be planting citrus plants. Then I will replace the raised bed with new soil. Would this work well or will it just cause problems to my citrus plants? I’d love your input.   Root know nematode on tomato A. Nematodes are very tough to impossible to get rid of if you have them. I should say they are basically impossible to get rid of. Be careful and do not move soil from this spot to other areas or you will move the nematodes as well. Nematodes only infest plants, not animals so all animals are safe around these guys. Soil solarization will help knock back the populations but not get rid of them. There are some products like Clandosan (a natural product) which are supposed to help but I would not be too optimistic. Even with fumigation it does not get rid of them buy just knocks them back.             Use vegetables that are nematode resistant and fruit trees on rootstocks that resist nematodes. On vegetables they will have the designation “N”below the name somewhere. Other letters might also appear like “V” “F” and the like which just stands for resistant to other pest problems like Verticillium (V) and Fusarium (F), two prominent disease problems. Nematode resistant rootstocks for fruit trees include Nemaguard, Citation, Viking, Atlas, Myrobalan, and Marianna. Hope this helps.  

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