Planting During our Desert Heat

Leaf scorch can be a reminder that the plant might be in a hot location, soil not amended properly or it was not surrounded by wood chips when it should be.

 Avoid planting anything during our desert heat. All planting should stop if it's windy or temperatures are above 100°F. Sometimes you must plant but think about other times. They will be better and you will have more success. Planting during cooler weather is better for the plant. Planting during cooler weather and you will have more success.

If you must plant during the heat:

Plant in areas of the landscape appropriate for the plants. Some plants tolerate desert heat better than others. No plants like heat. They prefer growing at temperatures they like (45F to 85F depending on the plant).

Dig planting holes and amend the soil a day ahead. Fill the planting hole with water when you're finished.

Plant only during early morning hours.

Avoid planting on windy days. Check your phone weather app.

Have water ready and available. Would you like some coffee you like some coffee no?

Always plant in a "wet hole", never a "dry hole".

Plant as soon as you get home. Never wait for tomorrow.

Keep plants roots wet. Feeder roots in without moisture die within 15 seconds. How many roots die determines the degree of "transplant shock". Transplant shock isn't "normal".

Leaves Browning on Palm May Be Lack of Water

Q. I moved here a year ago and have yet to figure out what this tree needs to thrive.  I located and uncovered the drippers to make sure it was getting enough water.  I removed a lantana and a Mexican bird of paradise that I thought might be robbing it of moisture.  I think I may need to rake back the rock and provide mulch around the base.

It puts out new growth, but it soon turns brown and the tree looks pretty sad.  I thought that leaving a few of the dead fronds may provide the new growth with shade.  So far that hasn’t helped.

The tree is in the east side of the house and gets morning sun.  It is shaded by the house to the west and a large palo verde tree on the south side of the house. 

Any help would be a life-saver.  My other palms seem to be thriving, but this little guy is sick.

A. It looks like a windmill palm. What I'm looking at looks exactly like a lack of water. I hope you are not watering every day. You should give plants like this a long burst of water and then hold off before you water again. In the summer this might be 2 or 3 days apart. In the winter this could be a a week to 10 days apart.

 Windmill Palm and Drought

Windmill Palm will have leaf scorch a little bit in our climate but not that much. If that exposure is on the south or west side of the house it's probably a bad location for it because of the heat reflected off of the house and also the rock below the palm. That location can be very hot.

 What Todo

You can get some of that leaf scorch to disappear by adding more drip emitters around the palm and making sure that it gets enough water. I am guessing that your palm should receive about 15 gallons each time it's watered. I would have at least 4 drip emitters under that palm, located about 18 inches from the trunk. The amount of water depends on how many minutes the drip operates. Let's say you have it watering for 60 minutes. Then you would need for drip emitters that are 4 gallons per hour located under the palm tree. If your system is on for 30 minutes then I would have 6 drip emitters under the canopy and these are the 5 gallon per hour.

Another alternative is to not use drip emitters but a coil of drip tubing circling the tree.  .Let's again say you are running it for 60 minutes. This tubing would be connected to your irrigation supply line and be about 15 feet long. The tubing would have emitters embedded in the tubing 1 foot apart and they would be 1 gallon per hour emitters. If you are watering for 30 minutes, then use a coil 30 feet long circling the Palm multiple times. The tubing would be put under the rock. In any regard, the problem appears to be not enough water is being applied.

Bottle Tree Leaf Drop

Q. You told someone that a bottle tree lacked water when its leaves turned brown and fell. I have a large, Australian bottle tree that was here when I bought this house 12 years ago.  Every summer it blooms and makes seedpods that eventually fall.  It also loses leaves as the person in your article described. However, it grows new leaves so it looks eventually much as it did.

Bottle tree with one side of the tree leaf drop

A. Bottle trees from Australia are “dry deciduous” trees. In other words, during the dry season of the Australian desert they drop their leaves. When rain returns, they grow their leaves again.

If these trees get water stressed in our climate and suffer from a lack of water, they drop their leaves. They “think” they are going through a dry season so they drop their leaves to protect themselves from drought.

During the summer here, if they are not receiving enough water they will also drop their leaves. They are conditioned to drop their leaves from millennia of evolution on the Australian continent.

If you want them to keep their leaves through the summer, then give them more water or, possibly, water more often. It is hard to say which is the right thing to do but my guess is they should be given more water when they are watered.

Plants use 500 to 800% more water during the months of July and August when compared to January in our desert climate. When bottle trees mature, they develop a swollen trunk that they use for storage of water that allows them to survive periods of drought, thus their name.

Help Save My Photinia from Dying

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.

Apricot Leaves Cupping and Dropping

Q. My Blenheim apricot tree is not doing well. A few branches have lost all their leaves. Other leaves are starting to curl and cup.

Rose Leaf Scorch Probably a Soil Problem

Q. I have some roses doing poorly. Any thoughts?

A. If I see it correctly, it looks like rock mulch in the background. No, no, no for roses. This leaf is showing leaf scorch and marginal tip dieback, a sign of fertilizer, soil and water conditions. They are all inter-related.

The first thing we need to consider is soil improvement. In our desert soils they need massive amounts of organic material to bring it up to the bare minimum of 3 to 5 % organic matter for plants like roses. Our soils in Las Vegas are typically around 1/10th of 1% organic matter. Organic matter breaks down over time so to accomplish a 1% change will mean about a 25% volume of compost added to the soil at the time of planting.

Surface mulches made of wood mulch like the kind made from chipping trees will contribute organic matter back to the soil and replenish what is lost over time. Bark mulch will not contribute much of anything. It is decorative only.

Water should be about two to five gallons at each watering. Watering frequency with surface mulch is about three to four times per week, basically every other day. In the winter this might be every ten days.

Fertilizers should be one that promotes flowering, adequate in phosphorus, and balanced with all three numbers present. The first number, nitrogen, should be a relatively high in number. Potassium, the third number would be anywhere from half the value of the first number all the way up to an equivalent number. This would be applied in January or just before or during when new growth commences. Iron chelates should be applied at the same time. Small amounts of fertilizer can be applied every four to six weeks if these are for show. Rosarians suggest the application of magnesium in the form of epsom salt.

Oleanders Drop Leaves in Drought. Will it Recover?

Q. I read the post on your blog on oleanders with interest. I too have an issue. My five oleanders are mature (at least 20 years old) trees.  When we moved here a year ago they had not been watered.   When the water was turned on and major landscaping installed, many of the leaves turned yellow and dropped. However the trees blossomed and continued to do fine. 

This is not the readers oleander but this oleander has leaf
scorch and leaf drop while the oleander behind it is
doing very well. Check the emitters or the source of water.
This is a good sign it is getting a lack of water.

            During the rains the gardener turned off the water system and sadly forgot to turn it back on. The water is of course back on but I have had to replace many bushes, although NOT the oleanders.  However they have begun to turn yellow again and are dropping leaves. There are still a majority of green leaves and the trees are about to burst into blooms. They have been fertilized, as has everything on the property, but I am baffled.  Would you be so kind as to give me your advice on what is happening and why?

A. Oleanders are so extensive worldwide that no one is sure where they originated from. Their climate of origin is important because it determines under what conditions these plants perform best but we do know quite a bit about how oleanders behave with and without water.

            We know that they are very drought tolerant. This means that when there is limited water, they can survive. Many plants can’t do this. Normally when drought tolerant plants first experience a lack of water the leaves will drop and the canopy will become sparse. If the water continues to be sparse the leaves they produce will be few and smaller and little new growth. They have to have a sparse canopy to survive.

            However when water is present they have the potential for using a large amount of water and are not low water users. They respond to this water by growing more, setting new leaves that are quite a bit larger and shedding the old ones. The plant itself becomes denser and flowers profusely (provided they are not trimmed with a hedge shears).

            Leaf drop is very characteristic in response to a drought. It is also characteristic when they receive water again after a drought. It is also characteristic of older growth to shed some leaves on older wood.

            So, in a nutshell, going from drought to abundant water expect some leaf drop. And when oleander grows normally, expect some leaf drop as the plant matures but not typically as much as during dry/wet periods. So is oleander a good pool plant? No.