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Thursday, February 5, 2015

Trumpet Vine Adds Color to Desert Landscapes

Trumpet vine is commonly used in much colder, arid climates. It is not a true desert plant but can tolerate arid environments and poor soils. It does really appreciate amended soils, wood mulch and regular irrigations. Fertilize once a year in February with a fertilizer that promotes flowering of woody plants. It is a climber and under the right conditions can be extremely aggressive. Restrain with pruning the longest and most aggressive.

Usual complaints are that the vine grows slowly or poorly. Make sure it receives enough water and mulch the base with wood chips. It may not do well in extremely hot microclimates.

Trumpet vine over a wall in Las Vegas

Tuesday, February 3, 2015

Prune Mexican Petunia Similar to Lantana

Q. I have a Mexican petunia (Ruellia) that is about 4 years old.  In 2013 the freeze caused all of the stems to die back. I cut all of them off at ground level and the plant grew back nicely and flowered beautifully.  Apparently, this winter the plant has very little dieback. Should I cut all of the stems off at ground level or just the ones that have frost damage?  Will it flower from the existing stems or does it only flower from “new wood”?

A. Mexican Petunia is considered an herbaceous perennial which means it freezes to the ground if it gets too cold and grows back from the base. It is summer flowering so the flowers develop on new growth. Flowers will develop on new growth from older wood as well as from new growth at the bottom.
You have two choices. You can prune it to the ground again just as if it froze back. It will grow from the base and flower just like it had in 2014. That’s the easy way.
Your second option is to keep it at this height and remove anything dead or weak to the ground. Next, you would cut the remaining stems back to a height where you want it to branch. Cutting it back or shearing it will cause it to grow more densely above where it is sheared and flower.
The second method will give you a taller plant if you want one. If you need to keep it small, then use the first method.

Remember to fertilize it now with an all-purpose fertilizer for promoting flowers such as a rose fertilizer, fruit tree fertilizer, tomato fertilizer or something similar. 

Avocado May Shock When Moved Inside

Q. Last year I grew an avocado outdoors from its pit. As the temperatures began to dip I transplanted it to a pot and brought it inside.  The older leaves have begun to turn brown and dry up. I fertilized it once since bringing it indoors. I water it lightly every other day as the leaves begin to curl up due to lack of water.

A. The main reason leaves drop from an avocado brought inside is the change in light intensity or duration. Moving it from a soil to a container can cause leaf drop as well. Leaf drop can be caused by a watering problem. A fourth possibility are pests like mites.
Avocado. Picture from the California rare fruit growers.

Plants grown outside develop a different type of leaf than plants grown inside. The change in light intensity causes leaves grown outside, called sun leaves, to drop. The plant begins to add new growth with a thinner, larger leaf called a shade leaf.
Disruption of the root system can cause leaves to drop. We call this transplant shock. It is also possible that the change in watering could cause leaf drop. Avocados are prone to mite problems so if there are mites on your interior plants it’s very possible they were transferred to the avocado.
What to do? Make sure the avocado gets as much sunlight as possible. A south facing window is probably best. You need to provide several hours of sunlight to keep it healthy and prevent it from becoming spindly.
Spider mite damage on interior foliage plant

Water the soil in the container until water comes out the bottom. Do not water again until you can feel a dramatic change in the weight of the container. Another method to judge the moisture in the soil is to use a pencil or soil moisture meter.
Push a pencil in the soil and see how easily it pushes down. A pencil is more difficult to push in dry soil than wet soil. You will feel the end of the pencil after you remove it to see how moist it is. A third method is to use a soil moisture meter you can purchase at any nursery or garden center.
Mites are common problem for avocado. There are two methods you can use to inspect the plant for mites. First, take a white piece of paper and slap a yellowing leaf against its surface. Pick up the piece of paper and look at it carefully under a bright light.
If you have good eyes or a magnifying glass you’ll see very small mites the size of a pencil dot crawling along the surface. You can also drag your fingers lightly across the surface of the paper and the mites will leave a red smear.

Use a horticultural oil and spray the plant from head to toe to suffocate mites. Oils work well against active mites as well as soap sprays.

Snails, Disease and Shade Are Related

Q. I have been noticing tiny little snails climbing up my red brick planter during the fall. I have thousands of those shells all through my planters and yard. My roses have now developed powdery mildew disease which they never have in the past. My lawn is thinning I think because of the snails. I have shade in my yard because of some older mulberries. I sent you some pictures of my yard.

Readers yard with shade
A. After seeing the pictures and reading your description I think that the shade is contributing to a number of things going on. Increased shade causes plants and the soil to stay wet longer.

Snail shells from another readers question
Staying wet longer favors snails and slugs. Increased shade increases the probability of powdery mildew and other diseases. Increased shade causes lawns to thin and eventually fail as well.
          You will see an improvement in everything if you remove some lower limbs of the trees. Limb removal will allow more light on your property and improve the roses, reduce disease problems, thicken the lawn and reduce snail problems.

Cool season lawn grasses like fescue and ryegrass needs direct sunlight at least five hours a day or filtered sunlight so that no more than 50% of the lawn is shaded. Shading lawns and flowering plants more than this is going to hurt them.
Shady lawns are not vigorous enough to withstand any kind of traffic. The lawn will thin and bare soil will appear in the more shaded areas.
Plants that flower, like roses, have fewer blooms and the blooms will be poor quality in the shade. Powdery mildew loves the shade. Powdery mildew also likes splashing water. If there is overhead irrigation that is splashing on the leaves of roses and they are shaded, it will spread powdery mildew from rose to rose.
          Snails are difficult to control. The usual control methods are trapping and baiting. Trap snails by placing wet newspapers or cardboard between the plants. When the sun comes up, snails and slugs like to have parties under wet paper or cardboard.

Powdery mildew on rose

Pick them off of the underside of the cardboard or from the ground and put them in a plastic bag for disposal. If you do this on a regular basis, say weekly, you will start to put a dent in their population.

Snail and slug baits also works well on snails. These are typically spread around the plants periodically and according to the label. These can be purchased in most nurseries and garden centers or online.

Persimmons Will Grow in the Mojave Desert

Q. I recently received a large bag of home-grown Fuyu persimmons given to me, grown in California. Will the Fuyu Persimmon tree survive our Las Vegas climate?  If the tree will grow here?

A. Nearly all of the persimmons will grow in this climate. I wouldn't recommend the variety called ‘Hachiya’ but Fuyu, giant Fuyu, Coffee Cake, and most of the others will grow here if they are planted correctly in amended soil and not part of a desert landscape surrounded by rock mulch.
Immature Hachiya persimmon. Hachiya may not be the best type of persimmon to grow in the desert unless you are in a backyard situation, protected from the wind and plenty of moist air.

The fruit is good quality but the fruit may sunburn because of our high light intensity.
It is important to surface mulch them with wood mulch, fertilize them once a year, prune them in a very similar manner to most other fruit trees and irrigate them as you would any other landscape plant.

Giant Fuyu which does well in the desert

Video Help Pruning Peach to Keep it Small

Q. I wonder if you can tell us how to prune our Elberta peach tree. We planted it in the spring and had one beautiful peach to enjoy. We are in our mid-70's and do not do ladders unless we have to and it is getting over 6' now and is supposed to be a semi dwarf.

A. You may begin to lower the heights of peach trees at the first sign of leaf drop and possibly sooner. The cuts that you should make to lower the height should be thinning cuts and not heading cuts. To see the difference visit my video on how to make heading cuts and thinning cuts and what the difference is.

Some of my videos on pruning peach tree

 On the peach tree, go to my YouTube videos on pruning fruit trees. I think that might help you. They can be found at

Those videos on pruning focus on size control so you don't need a ladder.
Controlling the size of fruit trees by pruning

Irrigating Fruit Trees After Planting and During the First Year

Fruit Tree Establishment

During the first few weeks after planting, new roots must grow from older roots and into the soil used for planting. Learn how to plant fruit trees here. The growth of new roots from older roots and into the surrounding soil after planting is called fruit tree establishment. New roots can only grow from healthy, living roots. The smallest roots are fragile, resembling hairs, and are called feeder roots. See some feeder roots here. Feeder roots are responsible for most of the water and fertilizer taken from the soil and transported to the leaves. Feeder roots do not survive for more than a few minutes without soil, air and water surrounding them.

During planting it is normal that feeder roots and some of the larger roots will die. As the amount of time that roots are not in moist soil increases, more roots and more roots begin to die. As more roots die, the time needed for establishment increases and leaf and stem growth is delayed or the tree may become damaged.

More on transplant shock.
Still more on transplant shock.
Stop it, you're killing me, even more!

Fruit tree establishment takes time after planting. Fruit trees use energy stored in the roots for establishment. This same energy is used by fruit trees to grow new leaves and stems. Energy must be shared between the growth of the roots and growth of leaves and stems. The more energy needed by roots for establishment means less energy is available for the growth of leaves and stems.

After planting, fruit trees favor root growth more than leaf and stem growth. After the roots have grown significantly and can absorb enough water and nutrients, leaf and stem growth become increasingly more vigorous. Rapid and vigorous leaf and stem growth after planting is an indicator that roots have become established in the soil. This observation is when the Orchard manager can claim that the fruit tree has become established.

The time of day and weather conditions at planting time also affects establishment. The ideal conditions for planting fruit trees is early in the morning when temperatures are cool, the sky is cloudy and there is very little wind. Warm temperatures, bright sunlight and strong winds are the worst conditions for planting.

Irrigation after Planting

Drip irrigation on almonds. The first 2 to 3 years only requires one drip line. As they get older they will require two drip lines, one on either side of the tree.
All fruit trees must be irrigated immediately after planting. The reasons for this are several. When fruit trees are planted and soil is placed around the roots by hand or with machinery, large spaces filled with air are left in the soil surrounding the roots. If spaces in the soil are too large to hold water, tree roots cannot grow into these spaces.
Micro sprinkler beneath fruit trees.
Wetted area from a micro sprinkler on almonds.
Sprinkler from Jain irrigation
It is very important to collapse these spaces around the roots of trees. This helps the tree to remain upright and the collapsed soil surrounding the roots can more easily hold water. The easiest way to collapse these spaces is through irrigation. Irrigating the soil around the roots helps to collapse air spaces around the roots. After soil spaces have collapsed, roots can grow into these spaces and take water and nutrients.

To maintain rapid growth after establishment, adequate amounts of water is needed by the roots. Watering too frequently results in the roots “drowning” or suffocating from a lack of air. Not watering frequently enough results in roots dying from dehydration or a lack of water. The Orchard manager must determine when to irrigate with observations of the soil, not the tree. If the fruit tree shows signs that water is needed such as the dropping of leaves or wilting, establishment will be slow.

It is best to judge when to irrigate by observing the soil. The ideal time for the second and following irrigations can be determined easily by using a shovel, a sample of the soil and your hands. Use the shovel to dig and remove a handful of soil at the depth of the roots close to a tree. Squeeze the soil tightly with your hand. Lightly bounce the soil in your hand. If the soil falls apart easily after bouncing, it is time to irrigate. Soils that contain a lot of sand must be irrigated more often than soils which do not. As the summer months approach, fruit trees real require irrigations more often.

How to Prune Fruit Trees

In case you missed my classes this spring, below is an updated version of some short notes on pruning fruit trees. This covers most of the major temperate fruit trees such as peach, nectarine, apricot, Apple, pear, plum, pluot and the rest of that group.

Unfortunately it does not cover pomegranates, citrus and nut trees. I  post something in another post on citrus and nut trees. Pomegranate is a different animal altogether and I will post something soon on this as well.

Below are my updated notes on pruning that I put together for training purposes in Tajkistan for a project working with local tra and fruit growers.

If this doesn't work for you, here is the link by clicking HERE
Don't forget to visit my YouTube videos on pruning which can be found 

Happy Pruning!