Xtremehorticulture

Keys to Healthy Landscape Plants in the Desert

Q. We have several shrubs with an eastern exposure that appear to be very distressed or dying. The first three photos show the entire shrubs. Photos 4 and 5 are close ups of the distressed area. Photo 6 is a very healthy plant in the same area but with a southern exposure. Irrigation is excellent; enough that water is standing in the bed upon completion of the water cycle which is five minutes and four times a week in the hot summer.  Japanese euonymus in question A. Thank you for the pictures.  There are several things that might be going on at the same time with these shrubs.  They appear to be variegated mock orange and Japanese euonymus.  Many of the leaves are yellowing and scorching or turning brown and dying from the tips back.              Most people will look at these pictures and say they are not getting enough water.  Another person might look at the same pictures and say they need iron. Another person may look at the same thing and say they are getting too much water. And even another person may look at that and say it is salt damage. The problem is they could all be correct just based on the pictures.  Leaf damage closeup of Japanese euonymus             Many of these things, and even more, are interrelated.  Just giving more or less water or even iron may not solve the problem alone.  Let me just give you a rundown of the problems that I see as possibilities: plants planted in the wrong spot in the yard, improper pruning, lack of additions to the soil to improve it, wrong type of fertilizer and improper watering.              From these pictures, any of these could be a possibility and there could be combinations of things going on.  Let me handle each, one at a time and perhaps you can make the best decision. First of all plant location.  If this is a very hot location, facing south or west with lots of reflected heat and light, then they will not do well in this spot. This does not mean that they cannot survive there; it just means it will require more effort to keep them looking good if they are placed in spots that are extreme for their best health.  Variegated mock orange with scorching and dieback             By finding the best location for plant in a yard means that they will require less time, energy and money to keep them looking good.  A very hot location will be even more difficult if there is no air movement and they just sit there and bake. Pruning. These shrubs appear to be pruned with a hedge shears into the shape of a gumball.  This type of pruning may work for a few years but eventually this type of pruning makes the plants look ugly and contribute to their poor health.              Pruning with a hedge shears should be reserved for hedges, not shrubs.  This type of pruning forces older wood out closer and closer to the perimeter of the shrub.  Young or juvenile wood is the only wood that is removed.  Closeup of variegated mock orange leaf scorch             My guess is that you have a landscape maintenance company doing the maintenance.  This is how they prune. They don’t know any better. Very few, if any, prune shrubs properly. The proper way is to remove ¼ to 1/3 of the shrub each time it is pruned, forcing new growth to come from old wood deeper inside the canopy of the shrub.  This rejuvenates the shrub, adds more juvenile wood to the canopy and keeps it young and vigorous. Soil amendments.  I could not tell from the picture but these shrubs will perform better if they were growing in organic mulch or wood mulch.  Not bark mulch.  The chipped wood decomposes into the nutrient poor soil and adds vital nutrients for the shrubs.              Rock mulch also breaks down but adds only minerals to the soil.  The shrubs will perform better if compost is added to the base of the plants and watered in with a hose.  Compost should be added to the list of fertilizers and soil improvements for these plants each year.              The first year I would add about 4 cubic feet of compost per plant along with its fertilizer applications.  After two or three years of this I would probably only add about 2 cubic feet per year.  Then of course the wood mulch is an added on top of the compost.  You should start to see improvements after one full season of growth after the additions.  Fertilizers. The same type of fertilizer used for lawns will do a good job on most shrubs as well.  This is usually a fertilizer with a ratio on the bag of 3-1-2 or 4-1-2.  An example of a 3-1-2 fertilizer would be something like 12-4-8 and a 4-1-2 might be 16-4-8.  You will not find these numbers on fertilizer bags exactly but at least you can get the idea of how the numbers should go up and down in sequence.              The next fertilizer you need is an iron chelate such as iron EDDHA.  It is expensive but can go a long way since of the small amount is needed each year.  My apologies to other nurseries and outlets but I know that Plant World Nursery carries this iron chelate.  If others do, let me know please. Fertilizers are added to shrubs in February of each year. Watering. The frequency of watering will vary during the year but during the heat they will probably need water about three times each week.  As it gets cooler, decrease that to twice a week, cooler yet, than once a week, etc. In the winter it should be no more frequently than once a week.             The gallons of water to apply is going to be difficult for you to judge because you operate an irrigation clock in minutes. Somehow

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Hawaiian Tomoto Plant with Yellow Leaves May Be For Many Reasons

Q. I have 4 Hawaiian tomato plants in containers, all producing tomatoes.  On one plant the leaves on lower branches are turning yellow.  The plant appears to be healthy having several flowers and small fruit forming. I fertilized all 4 plants 2 weeks ago with Miracle Gro and was planning to fertilize in 2 week intervals as suggested on product container.  What can be done to prevent the yellowing of leaves on the other 3 plants and resolve the present problem with the one plant in question? A. There could be several things going on. My first reaction was a lack of nitrogen fertilizer until you told me you were using a fertilizer on a regular basis. When plants don’t get enough nitrogen fertilizer the older leaves can turn yellow and die.             You can also look at how much new growth there is since nitrogen is also responsible for stem and leaf growth. If it is not growing and putting on new growth then this can also be an indicator of a lack of nitrogen.             Watering too often and keeping the soil too moist can also cause yellowing of foliage. So if you have mulched the soil and watering frequently then this might also be a potential problem.             Some soil amendments if they have not broken down completely can cause yellowing but this is usually compensated by using fertilizer high in nitrogen. Also poor grade composts can cause yellowing so try to avoid the very inexpensive composts and soil amendments. Good soil amendments are expensive unless you make your own.             If the soil is native desert soil that has been amended with compost or soil amendments, salts can cause yellowing of leaves. There are lots of natural salts in desert soils, frequently at levels too high for most of our landscape and vegetable plants. If your soil is fairly new, it make take a couple of years of compost and growing to get it into good condition.             Salts are removed by leaching or watering the soil with lots of water in and letting it drain over and over in repeating cycles. Salts dissolve easily in fresh water and the draining water carries dissolved salts from the soil to a depth below the roots of the plants. If you use composted native desert soils you should always leach the soil prior to planting.             So look at your soil modifications, how you are watering and whether you have leached the soil or not. If after this you think there is still a problem you might consider replacing the soil.

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Make Jelly From the Fruit of Your Ornamental Plum

This is cherry plum, not from the ornamental tree but the same fruit sold as Delite cherry plum Q. We have a flowering plum (supposedly ornamental) tree in our front yard.  This year it is covered with small walnut sized plums.  Are these edible?  I am envisioning plum jam if they are edible. A. Yes they are! These plums are sour but great flavor so use lots of sugar and follow your favorite plum jelly or jam recipe. By the way, it can also be used to make wine or infused into vodka or grappa with sugar and let it stand for three to four months or longer. I was put to shame by one of our local winemakers who brought me some of his ornamental plum jam and another with his infused vodka. Purple leaf (ornamental) plum             Because the plums are so small wash and put them into a pot and add enough water to cover them. Boil them for 20 minutes or the skins pop. Mash with a potato masher. Continue to cook another 10 minutes. Let cool.             Strain mashed fruit through cheesecloth or jelly bag. Add Sure Jell to filtered juice and extra water and bring back to a rolling boil, stirring all the time. Add butter and all the sugar and boil for one minute. Skim and pour into jelly jars.  Ornamental Plum Jelly 4 c. plum juice 1 c. water 6 1/2 c. sugar 1 box Sure-jell 1 tsp. butter

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Crape Myrtle and Mimosa (Silk tree) Similar in Care

Readers silk tree in excellent shape in rock mulch Q. I have a mimosa tree and I am giving it a lot of TLC and it seems to do well here. A. Your Mimosa or silk tree looks great and is doing well judging from the picture you sent to me.  It looks like it has good growth and a nice dark green color.  You must be giving it a lot of attention as it seems to be thriving there in rock mulch.  I will caution you that these are not long-lived in our climate and tend to suffer a lot of branch dieback or decline as they get older.             They particularly struggle in rock mulch that is fully exposed to summer extremes.  They seem to live a bit longer when surrounded by grass rather than rock mulch.  It has never been diagnosed, to my knowledge, but this decline may be mimosa wilt disease, a disease that infects and plugs the vascular or water transporting system in the tree.  Crape myrtle 20 years old growing in alkaline pH 8.2 soil with little soil amendment  following regimen suggested here. There is some wood mulch at the base of the tree in the irrigation well.             Continue to keep it healthy and it’s possible to keep it going for quite a while.  Another plant which can suffer here in rock mulch is crape myrtle but is, in my opinion, a better tree for here if you give it some TLC like you are doing.  With this tree you can keep it looking good growing in desert soils by fertilizing it with a well balanced fertilizer like 16-16-16 in late January along with iron chelate applied to the soil and watered in.              Follow this about two months later with a liquid fertilizer applied to the leaves until the solution begins running off the leaf surface and dripping onto the soil.  I usually apply a wetting agent with the liquid fertilizer applied to the leaves.  If you can keep plants healthy, they can withstand diseases and extremes of temperature and soils better

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