Xtremehorticulture

Xtremehorticulture of the Desert

Figs Dropping From Tree

Leave a Comment / desert, falling off, fig fruit, green, irrigation, Las Vegas, Mohave Desert, Mojave Desert, mulch, nevada, not mature, small /

Q. We planted a fig tree a couple of years ago. Year before last it produced a couple of figs. Last year there were perhaps a dozen figs which never got larger than a small grape. These did not emerge until November and never grew to full size. The tree was fertilized with 16-16-16 commercial fertilizer, and had plenty of water. Can you tell us why the fruit did not mature and what we might do to have a better result this next season? A. The usual problem is not watering at the right time and keeping the soil moist during production of fruit. We can get two good crops of figs here. The first one is called the Briba crop and is borne on last year’s wood (2013 growth). This is the Briba crop. Notice how the figs are developing on older, brown wood from last year. You can see the new growth pushing from the terminal bud, is green and about two inches long.             The second crop is the Main crop and grows on the current season wood (2014 growth). If the tree is pruned or last years wood is killed by freezing weather, you will only get a main crop. This picture shows you the larger Briba crop still developing at the bottom on older wood. Above these fruit are smaller fruit still developing on this years growth, the main crop. The Briba crop will be harvested while the main crop is still developing.             The main crop occurs when it gets hot and if the tree is not getting enough water the figs will get button sized, get hard and drop off. There is a potential third crop in about September and October but the weather does not stay warm enough in the fall for it to mature.             This third crop will get button sized and will fail to develop due to winter weather coming in. That third crop may form without the summer crop if the tree is not getting enough water. Then in the fall it is getting enough and tries to set fruit but it is too late and fails. Although this is another readers picture, this is what this reader is probably talking about. Late season figs never get to ripen. However, if you keep the soil moist during the summer months, the first two crops will ripen.             I would mulch around the tree with about four inches of wood mulch and cover the soil to a distance of about six feet from the trunk. Water in a basin around the trunk about six feet in diameter.             The basin should be able to hold at least two inches of water but four would be better. Fill the basin with water each time you irrigate. Water once a week now, twice a week in May, three times a week in June, drop it to twice a week in September and once a week mid October.             Once the leaves fall off in winter you can water about every 10 to 14 days. Fertilize once in February with a fruit tree fertilizer or four fertilizer stakes per tree, one in each quadrant of the irrigation basin.

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Potted Meyer Lemon Flower Drop

1 Comment / container trees, desert, fertilizer, flower drop, freeze damage, fruit drop, irrigation, Las Vegas, Meyer lemon, Mohave Desert, Mojave Desert, nevada /

Q. You helped me before with my Meyer Lemon, so I hope you have an answer for this one. My tree is in a huge pot. It is about 4 years old.             Last Spring, it had massive flowers (yum) and a lot of little green buds followed. Then every single one of those buds turned black and dropped off.  Not one remained. I want to figure out why and change what I am doing so this never happens again.             The plant is fertilized with granular fertilizer 2x a year — early spring and late summer. It gets moisture and hasn’t dried out.  However the leaves could look more beautifully green. Sometimes, some of them curl and are not quite bright green.             I do not know if the two issues are related, but I sure hope you have a suggestion. A. Sounds like you had post bloom fruit drop. Fruit drop can also occur during summer months and just before harvest. The usual reasons for post bloom fruit drop is usually some sort of stress.             Four years is getting up there for being in the same pot without repotting. You might consider repotting and adding some new soil to the mix. Meyer lemon flowers             I know you said it had adequate water but if it went through just a few hours of drought during or just after pollination, fruit drop may occur. If we have some freezing weather during or just after flowering, that can cause the fruit to abort too.We had some on January 6 and 8 in parts of the valley.             When watering, make sure about 20% of the water that you apply runs out the bottom of the container each time you water. This is important for flushing salts from the soil.             Another possibility in containers is overheating them. If in direct sunlight and the outside of the container gets too hot and transmits this heat to the soil, this can cause stress and cause fruit drop.             Proper fertilization is important. Over fertilizing fruit trees, excess nitrogen, can cause fruit drop. And finally less commonly some insects such as scale or mealybug infestations can cause fruit drop as well.             What to do? Make sure your container, the soil volume, is big enough to handle wide swings in temperature and water. Monitor both closely. You might find a houseplant moisture meter to be helpful.              Keep the outside of a plant container out of the hot sun. Double potting a container is  helpful to keep the soil temperature down. Watch for freezing temperatures at bloom time and cover the plant.             Water the soil just before the heat of the day. Wet soil heats up more slowly than dry soil. If we have any frost during bloom it will affect fruit production.

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Bring Back Queen Palm from the Dead

Leave a Comment / cold, heat, iron, irrigation, queen palm, summer dieback, yellow /

Q. During the excessive hot spell in July our irrigation failed while we were out of town. As a result, one of our queen palms lost all its branches. In spite of subsequent life support, it does not appear to be coming back. Is that too much to hope for? Is there anything we can do to help it recover or should we just mourn its passing? Queen palms dead during first winter planted (1989/90) at local casino. Admittedly temperatures hit a 50 year low. A. Queen palms can handle heat but they struggle with extreme cold (25F) and hot, dry winds. In short, among the approximately ten palms we can grow here, they are not among the “chosen ones”. However, if these plants are water stressed or planted under poor soil conditions then they will not tolerate heat very well either.  Queen palm fronds from central bud yellowing during new growth             The only places here where I have seen decent, older queen palms has been in areas protected from wind, the soil prepared adequately with amendments and the use of organic surface mulches.  Queen palm with yellowing foliage after planting in rock mulch. Probably iron chlorosis and poor soil enrichment at planting.             Once they are stressed and water is withheld, they will suffer greatly. They need adequate soil preparation at the time of planting, good drainage, protection from winds and low temperatures, an annual fertilization program and organic surface mulches.

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Mesquite Bushes Can Be Trained to a Tree

Leave a Comment / form, growth, honey mesquite, irrigation, management, pruning, riparian, training, watering /

Q. I grew up in a part of Texas where mesquites were bushes not trees.  We have a small backyard here in Vegas with two mesquite trees in it; one large one and one slender one. There is little or no green on them, just wood. There are so many woody branches I am wondering if they will ever give us shade.  Would you please educate me on this? Native honey mesquite growing in the Mojave Desert just outside of Las Vegas, NV A. The Texas mesquite or honey mesquite is a shrub that we prune into a tree form. The plant grows well here but is usually not a preferred type of mesquite because of its long thorns. There are improved types of mesquites that are usually preferred.             With a little bit of care when they are young they can be trained into a tree form.             In our climate many mesquites drop their leaves in winter and so are considered deciduous to semi evergreen due to winter cold. In warmer climates they tend to stay evergreen during the winter unless there is a cold spell.  One of the ornamental mesquites in the nursery trade, claimed to be thornless, showing dense canopy and shade, a sign of abundant water.             We consider our local mesquite to be a riparian species of plant. In other words it puts on growth when water is available and slows down when water is not. When mesquite trees are watered frequently they can put on large amounts of spindly growth, perhaps 8 feet or more each year.             Mesquite are normally very deep rooted plants in the wild. Being deep-rooted gives them the capability of avoiding long periods of time without water. For this reason they can be very drought tolerant if they have rooted deeply. Native mesquite growing in the Sonoran Desert near Jerez, Mex, demonstrating sinker roots tapping into deep water from a nearby river.              If mesquite trees are watered too often, their roots will tend to be shallow and not deep-rooted, a frequent problem in over-irrigated landscapes. They also tend to put on a lot of wood because of frequent irrigations.             Mesquite trees handle pruning very well and their growth is very adaptable to landscape management. They do well with light fertilizer applications annually. They should be grouped with other desert plants for irrigation purposes.             After training these plants into a tree form they do not require a lot of pruning. In fact heavy pruning just encourages a lot of new growth. I would remove lower branches just high enough to allow traffic to pass under them.             Frequent irrigations will cause these plants to be lush and provide dense shade. Watering less often will cause them to become more open and provide lighter shade. Remove branches that are crossing or growing too close together.             Limbs would be removed at their point of origin, not by hedging or simply cutting them back.

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Podocarpus Leaf Scorch Update from Previous Question

Leave a Comment / fern pine, how much water do trees use, irrigation, sunburn, sunscald, watering /

Q. Thank you so much for responding to my letter. I did want some clarity on these trees because I was surprised you determined this was a watering and not sunscald. First off, these trees are in a courtyard about 5 ft apart and they are on the same run station.  The trees on the south wall are actually shaded by the wall.  The trees on the north wall are getting more direct sun, so I figured the leaves had sunscald. If you don’t mind my asking, why do you think it’s a watering issue? I clearly diagnosed it incorrectly so I’d like to learn how to better diagnosis this issue if I come across this again. Readers Podocarpus with leaf scorch on the north side.  Podocarpus showing no signs of leaf scorch and with rock mulch, a potential problem in the future. A. I recently started a Yahoo group discussion page because I felt my blog did not give enough opportunities for discussion. It can be found in Yahoo Groups as [email protected] As long as you become a member (which is free but you have to be admitted by the Administrator) you can ask questions, post your thoughts about someone else’s comments or add with your own experiences. It is meant for sharing information. To send a question for my blog you have to send it to me in an e-mail which is [email protected]             It is always difficult to assess a situation remotely. I have to rely on what I know about a particular plant, our climate and soils and my personal experience. I have these plants myself and they are located next to my home on the east side. They get a very small amount of water but it is regularly applied.             First of all, we know they are not true desert plants so we have to add a lot of extra things to get them to grow well here. Soil improvement at planting times is one of them. They will do better with wood surface mulches as well as long as you keep them away from the trunk during the first five years. Besides that, the microclimate or their exposure to the elements can make a difference.             I also know that these plants can suffer if they get watered too often or if they don’t get enough water. The problem is, they look similar if they get watered too often or not enough. When they get watered too often, the roots begin to die. Once the roots begin to die they can’t take up enough water and they look like they are drought stressed. Drought stress will be leaf tip burn like yours or even branch dieback if it is extreme. If it is a chronic lack of water in summer months they usually have leaf tip burn.             I know that plants growing on the north side of the building, or the east side as in my case, are in a cooler location than they are on the South or West sides. High temperatures, wind and lots of sunlight drive plant water use up tremendously. So, plants on the north side and East side will not use as much water as they would on the South and West sides. (As a side note, ideally, we should be irrigating plants on the south and west sides differently than the plants on the north and east sides. This means they should be on different valves.)             You called it sunscald and in a way you are right. Usually the term sunscald has to do with burning of the limbs and trunk of a tree, not the leaves. But that is a technical issue and you would not necessarily know that as a layperson but I got what you meant. We would actually call this leaf scorch or tip burn. Leaf scorch on mockorange             Leaf scorch typically occurs around the margin of the leaf. Leaf scorch occurs because not enough water is being pulled by the roots of the plant and transported to the leaves. The margins of the leaves, or edges, are furthest from the veins and they are the first to show a lack of water, resulting in scorch.             A lack of water can occur because not enough water is applied, or there is root damage so it can’t take up enough water, or the plant is just is not suitable for a very hot and dry climate and it can’t take up enough water in enough volume. We see leaf scorch in plants here like the really big sycamores (that always get cut down when they are about 15 years old because they look so bad) and a few others. Sycamore with leaf scorch due to reflected heat from south facing wall We will also see leaf scorch from plants that are stressed in other ways. For instance, if a plant is suffering in a lack of a nutrient, like iron in iron chlorosis, it will scorch when the same plant which is healthy will not. An unhealthy plant just cannot handle the extremes like a healthy one can. Leaf scorch resulting from iron chlorosis in apricot               Your plants have leaf scorch or the leaves are dying back on the north side but they are doing well on the south side, as you said. I am assuming that the plants on the north and south sides are getting similar amounts of water. If they are good on the south side, then it appears like they can handle that very hot and bright exposure okay (at least for now).             These same plants should have no problem handling a north (less stressful) exposure … but they ARE having trouble. So I ask myself, why do they look poorly on the north side when that should be where they look the best? The reason they look bad on the north side is because of leaf scorch, judging from your picture.             Leaf scorch is a lack

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Watering Citrus in Bullhead City

Leave a Comment / citrus, irrigation /

This is an irrigation basin around a fruit tree. The basin keeps water contained near the tree where the roots are. This basin receives its water from a bubbler (upper left inside the basin). This particular bubbler puts out two gallons per minute if the water pressure is adequate or above (it is pressure compensated which means if the pressure is higher than adequate it will still give only 2 gallons per minute) I have three trees  planted in a “L” shape with the orange and lime on the bottom of the “L” and a lemon on the top. They are about 6 years old and the trunks are about 5” in diameter. They are almost 6 ft. tall and about 7 ft. in diameter. I have the three on a separate circuit with each having a 1/2 “ p.v.c. bubbler providing water every other day at 6:30 a.m. and 8:30 p.m. for 15 minutes. this fills a water well that is about 4” deep and 4 ft. across for about 10 minutes after the water goes off. The water is then absorbed into the ground.             I have tried to let the water run longer but it seem’s to want to go outside of the well and not deeper into the well. I thought about cutting down on the flow so it would run longer and maybe soaked in to the well better but I have not tried that. I have been told to water once every 90 days and let it run for 3 hours. I would have to cut the bubblers just to a drip or it would flood the yard. I don’t know what is the best option. I get a heavy crop of limes now but just a few oranges, and they are half orange and half green. any suggestions?  Remember this is in Bullhead City and it gets very hot during june thru sept A. I forwarded your question to Terry Mikel, retired Extension Horticulturist with the University of Arizona out of the Phoenix office who knows your location very well. Here it Terry’s response: I am familiar with much of the Bullhead City soils and conditions but I have yet to hear that watering every ’90’ days  . . . I should think, or hope someone might have meant or you meant every ‘9’ days .. . That would be certainly a point of clarification . . Irrigating citrus in Hermosillo, Mexico, at USON’s research farm. This is ditch irrigation which is terribly inefficient but still more efficient than flooding the entire field. Water moves toward the roots from the ditch through the soil. The most efficient would be drip irrigation and would not need a basin or ditch but is expensive for farmers with hundreds of acres.             I personally avoid giving calendar or numerical days for watering . . There are too many factors; for example, are you near the river with a heavy clay soil or up on the higher ground where the soil drains much better? . . .             It sounds like you are careful and meticulous about watching the growth and you should check the soil in the morning hours and water when it is dry down a couple inches . .  .Remember to check in the morning not in the afternoon when the heat will dry all soils there down a couple inches . . In the morning the soil will have the cooling  of the night to percolate water up from below thus rehydrating (fancy word for wetting) the upper soil zone . . . If you want to add more water and much more efficiently then change how you add the water . . Set the repeat cycle to  whatever time it takes the initial water to move into the soil and then run the set again instead of spacing it out for hours . . This is called surge watering and it works much better than the delay . . . Maybe next summer you can try and see if you can go more days between waterings without impacting the plant . . If you have a fast draining soil it might not work; likewise, if your soil is heavier you might . . . Don’t forget that a nice thick layer of mulch on the soil surface saves a lot of water from being lost into the air through evaporation . . . There are some great Master Gardeners in your area that are both knowledgeable and grow lots of things under your conditions . . With respect to the lime’s yield vs. the orange’s yield:  My first guess is the orange is a Navel type orange . . They are notoriously sensitive to hot dry condition and their fruits drop like flies . . The plant itself does well but the fruits you get are great but the number you get is usually a disappointment . . .It’s almost a shame they are sold . . . Terry Mikel

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How to Water a Landscape With Two Valves (One front, one back)

Leave a Comment / drip irrigation, irrigation, irrigation schemes, size and water use, water use /

Q. I have a LOT of different shrubs and trees on only 2 valves (front & back). The shrubs have 2 emitters per shrub and range from 2- 2gph for plants like photinia, red autumn sage, fountain grass, jasmine vines, rhaphiolepsis etc.; and  2-4gph on euonymus, abelias, boxwood, honeysuckle vines etc. The trees have more emitters. My landscaper told me to water 6 days per week for 2-20 minutes per day (equals 4 hours per week). Star nursery advised me to water only 3 times per week for 45 minutes per day. Plant World advised 6 days per week. So, what to do?             My biggest problem is my 8 year old magnolia tree, trunk diameter about 5″, has 4-4gph emitters. It used to be very full, now it’s about 10 ‘ high & the leaves are dark brown, dry and falling off.  All help would be appreciated. A. You even confused me. In their defense I would have to say it’s possible that all three could be right. Because plants are adaptable to different situations there can be several right answers to one irrigation question. Nurseries are there to provide service, the best answers they can muster up. I am an educator so let me take a stab at it from an educator’s point of view. I would like to give you enough information so you can solve your own problem with irrigation. But you I think already realize that this is not the best irrigation setup for conserving water. You will have considerable waste even though it is on drip irrigation just because you have so few valves. Bear with me on this. Let’s all agree for the most part that as plants get larger they will require more water. Let’s also agree that large plants will use more water, and considerably more water, is one smaller plant. The larger the plant, the more water it should receive. Irrigation valves are basically an on and off switch for water; when the valve is open, water flows. When the valve is closed, water stops flowing. Since you have one valve in the front and one valve in the back, these switches open water to all of your plants in the front at the same time and the valve in the back does the same for plants in the back. There are three basic questions that must be answered; 1) how long to water, 2) how much should be applied, and 3) when to apply it. The valves basically solve the question when to water. The drip emitters solve the question about how much to water. Irrigation clock answers the question when to water. The irrigation valves allow water to flow and the emitters determine the amount of water applied to each plant. The length of time the valve is open combined with the size of the emitter determine the amount of water delivered plant. This is where the confusion begins. To make it as easy as possible to irrigate let’s hold one of these variables constant. Arbitrarily, let’s hold the length of time the irrigation valve is open to one hour. Just for the sake of argument. It could be 30 minutes, it could be 90 minutes, but let’s just hold it at 60 minutes. If we make this decision first, how many minutes to open the valves, it can make our other decisions much simpler. So we now agree the valve will be open for 60 minutes for drip emitters. This is how I typically determine an irrigation schedule for drip. To determine how much water each plant will get we have to size our drip emitters. Because of plugging, it can be a little bit dangerous to give plants only one emitter. If that’s emitter plugs, chances are we will lose the plant in a short period of time during the summer. To determine how much water to give the plant at each watering or when the valve is on we look at its size. The smaller plants of course require less every time the valve is on. So for the sake of argument let’s do this. Let’s give a plant 1 gallon of water every time the valve is open (in this case one hour) for every foot of its mature size. A very small plant may get 1 to 2 gallons. A medium-sized plant may get 3 to 6 gallons. A large shrub may get 8 to 15 gallon every time it’s watered. The larger the plant, the more emitters it will need under its canopy. A very small plant may require one to two emitters. A medium sized plant might require 3 to 4 emitters. A large shrub might require 6 to 8 emitters. So now you will take the number of gallons you are giving this plant and divide it by the number of emitters you will provide for each plant. When you do this, you will determine the number and size of the emitters you will give to each plant. So for instance a medium sized plant may get 3 to 6 gallons at each watering delivered by 3 to 4 emitters. So the size of the emitters might be 1 to 2 gallons per hour. But I would keep all the emitters going to one plant at the same size. So what if it’s one or 2 gallons more than you calculated. What is important is that you apply enough water during one irrigation to water the entire rootzone of each plant (plus a little extra to keep those salts in our city water flushed out of the rootzone). So now we have answered two of the questions; how long to run the valve and as a result of that how much water each plant will get because you have selected the correct size and number of emitters. The next and last question is probably the most difficult to answer. Remember, you have elected to set the time that the

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Modesto Ash Landscape Tree Usually Does Not Establish a Tap Root

Leave a Comment / ash tree growth, irrigation, shallow roots, surface roots /

Q. I have a Modesto ash tree in my front yard.  I have had it for 12 years, so it is a big tree.  I am having a problem with its roots.  They are coming up through the grass.  Are those top roots?  They are ruining my yard.  What can I do for this problem?  I love the tree but not the roots. Surface roots of large tree. My picture, not the readers. A. This can be a problem with ash tree particularly if they are not watered deeply and were planted in a lawn. Lawns are typically watered with shallow irrigations because most lawn roots grow in the top 12 inches of soil. Since the tree is also growing in the lawn and receiving the same irrigation water as the lawn they will be in competition with each other for this water.             Maybe you mean tap roots and not top roots? Tap roots by definition do not grow on the surface of the soil. Trees with tap roots in nature seldom develop true tap roots once they have been replanted or transplanted into landscapes.             To develop tap roots trees need deep waterings or have deeper water available to them for their roots to grow into. In our desert environment most irrigations are shallow since water is expensive and we try to conserve as much as we can. In some cases you can remove a few surface roots without compromising the tree. You could explore this option.             Trees use their roots for taking up water and nutrients as well as stabilizing itself in the soil to keep it from blowing over. Tree canopies act like sails. If too many roots are removed, obviously this could result in the tree blowing over in heavy winds.             If you are removing more than one or two roots then you should consult with a certified arborist about the potential for blowover.

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Watering Santa Rosa Plum in the Mojave Desert

Leave a Comment / drip irrigation, fruit trees, how many gallons, irrigation /

Q. I read your gardening articles faithfully, and I just searched your blog for some help, but I would like more information.  I just purchased a Santa Rosa plum, but I am not certain how much I should water it.  I haven’t yet planted it, and I want to make sure to give it enough emitters as it is located in the front yard which is mainly desert landscape plants and therefore do not require as much water as this will (I think).  Santa Rosa plum The tag indicated how much water in inches, and I wasn’t certain how to convert that into gallons.  Also, although there is rock mulch in the front yard, I am more than happy to remove that in this are to give the plum the best chance.  Is that necessary?  Finally, your article on planting fruit trees from your blog mentions a “slurry” but I don’t know what that means, and I wasn’t able to find a definition on your blog.  I would really appreciate some help.  Thank you.  A. Plums are not desert plants and should not be irrigated as if they were desert plants. Mixing desert plants with non-desert plants on the same valve can lead to watering desert plants to frequently or, the flip side, watering the non-desert plants not often enough. But this may be a moot point. In this town desert landscaping means surrounding any type of plant with rocks. This is kind of like calling tofu, meat. Just because people put rocks around plants does not make it desert landscaping but does give it the appearance of desert landscaping. Hopefully your Santa Rosa plum will be on a valve that has other drip emitters on it. The first thing to do is determine your current run time for that valve on your irrigation clock; the number of minutes or hours that station or valve operates. It will be more difficult to irrigate your plum if the valve irrigates other things on it that are not on drip. Drip irrigation is designed to give small amounts of water over long periods of time, usually hours. Other types of irrigation such as bubblers or sprinklers are designed to operate in minutes, not hours. Mixing the two together on one the valve makes it very difficult to accurately apply water to either one. I like to see true drip irrigation operate a minimum of one hour. Let’s assume that the valve for your plum will operate for one hour. (Now I am going to give you some misinformation and tell you a couple of lies so that I can make my point. I will clear up the lies and misinformation later.) So, if the plum was purchased in a 5 gallon container, then make sure it gets irrigated with 5 gallons of water in that one hour. If it was purchased in a 15 gallon container, then give it 15 gallons in one hour. As a tree in a 5 gallon container gets bigger, you will need to increase the amount of water applied to it in one hour to perhaps 10 gallons or 15 gallons next year. You can do this by adding additional emitters; perhaps a second one next year and the third one maybe three years from now. If the plum is really growing fast you may have to add emitters sooner. This is a judgment call. Mature plums at the Orchard are getting 30 gallons every time they are irrigated. This 30 gallons is applied once every 10 days to two weeks during the winter to as frequently as twice a week in midsummer. As it gets hotter, the frequency of applied water changes, not the amount per application. Let’s say you now have discovered a problem. The valve which will irrigate your plum runs for 15 minutes, not one hour. And everything on that valve is designed to be irrigated in 15 minutes. This means we have to enter the dark side of irrigation; bastardizing drip irrigation to get it to do something it was never intended to do. Adjustable drip emitter: the dark side of drip irrigation. Now we enter the realm of adjustable drip irrigation emitters. These emitters can be adjusted with flow rates of zero (shut off) to a lot. Oh, they like to say it is 0 to 10 gallons per minute but in actuality who really knows? I don’t care what they call it but this is no longer drip irrigation. But in some cases it will get the job done and you may have no other choice. Plants surrounded by rock mulch use more water than plants surrounded by wood mulch. Any type of mulch will help but rock mulch will get hotter than wood mulch and drive water use up. Some plants should never be planted in rock mulch. Your plum is one of them. Others include roses, lilies, Photinia, mock orange, heavenly bamboo and many others. It might be okay for a couple of years but I will guarantee its health will decline living in rock mulch after just a few years. Organic mulches like wood mulch will help your tree a lot. This wood mulch should cover an area not less than 6 feet in diameter around the plum tree and be at least 4 inches deep. Be sure to keep wood mulch a foot away from the tree trunk the first four or five years. There is 7 1/2 gallons in one cubic foot of water. 1 inch of water covering one square foot is a little bit more than half a gallon, actually 6/10 of a gallon. Since rain is measured in inches of precipitation and sprinklers are also measured in inches of precipitation per hour there is a tendency to give watering advice in inches rather than gallons. They leave it up to you to determine how many square feet you are going to irrigate. A penstemon might be irrigated over an area of

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Rosemary Bush Very Susceptible to Dieback if Overwatered

Leave a Comment / collar root, dieback, irrigation, root rot, sudden death /

Rosemary dieback from reader Q. Can you diagnose what is wrong with my rosemary bush?  We have two rosemary bushes which are less than three-feet apart.  One is beautiful; the other has die-back in the center.  The one that has the die-back was replaced last year because the previous one had the same problem.      Both of these plants receive the same water and the same fertilizer.  When I replaced the rosemary plant last year, I did a 50/50 mix of compost and native soil.  I don’t see any pests on either of the plants.  Any suggestions? A. I looked at the pictures. There are no specific pests that would cause this type of damage on rosemary. The most likely culprits would be physical damage to the stems (broken stems) or root rot or collar rot from either planting it too deeply or keeping the soil around the one with dieback too wet. Healthy rosemary of reader             If the soil was heavily amended with mulch or compost and it was planted in this then it is possible it could have been planted too deeply while the other one was not. Sometimes plants will sink in the planting hole if the soil is too “fluffy” at the time of planting.             This sinking and soil consequently coming in contact with the stem due to follow-up waterings, can cause the main stem or side stems to decay and then entire stems can dieback.             I would carefully lift the plant out with a shovel and examine the main stem or trunk and side stems and see if they were planted too deeply. Rosemary is very susceptible to collar rot or keeping the soil too wet. If the stems are rotten, dispose and replant in a new location.

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