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Xtreme Horticulture

Posted 4/29/2008

"Horticulture under Extreme Conditions of Southern Nevada" Robert Morris, Area Horticulture Specialist Email questions to: morrisr@unce.unr.edu

March 17, 2008

Questions

  • Good apricot for Las Vegas
  • Pomegranate no fruit after second year in the ground
  • Other ways to know if you can remove stakes from plants
  • My gardenias are doing great!

Q. Could you recommend a good apricot for the home gardener? All the descriptions I read about for Goldkist, Royal and Moorpark apricots were the same, that they were sweet and juicy. I planted a Katy apricot which is supposed to be sweet, but the fruits are not sweet enough for me.

A. It is tough to really get specific on how fruit will perform in different places and climates. The quality of the fruit will vary with climates, soil types and how they were cared for. That is why it is valuable to have test and demonstration gardens doing some of those evaluations so we can help you decide. The advantages of Katy apricot is that it makes a very nice landscape tree as well as pretty good fruit. The tree is a vigorous grower, shows very little stress in our climate and is really a pretty tree. On our fruit evaluations of Katy’s, it typically scores a 4.0 on a 5.0 scale. Other varieties you might want to try for better fruit might include Royal Rosa, Blenheim, Canadian White Blenheim or Moorpark. Also try to avoid over watering just prior to picking and leave the fruit to "rest" for 24 to 48 hours in the kitchen before you eat them.

Q. I have a small pomegranate in my back yard next to the house with full south exposure. I assume that the lack of bees is the reason I had no fruit although I had a few blossoms this spring. This is the second year since planting this bush and the first year of blossoms. I only lightly fertilized in the spring and infrequently deep watered it this past summer.

A. Be patient. It will take a few years to get into production. The fruit is born on new growth coming from older wood so it will take awhile for your older wood to develop. Just don’t prune off to much new growth in the spring. Fertilize it in January and thin out the canopy so that there is enough room for the light to penetrate into the canopy. It is self fertile and does not need a pollinator. A common mistake is to think that because certain fruit trees are so-called desert trees, like pomegranates and figs, that they don’t need much water. This is not true. Any tree producing fruit needs to have water available to it all during fruit development if you expect to have fruit or have good quality fruit. Don’t skimp on the water as fruit is growing on the tree.

Q. We really enjoy your column, especially the article on removing tree stakes. Now the only problem is how to tell if our trees are well rooted and ready to stand on their own. They have been in the ground approximately nine months. They seem to be doing great. Anyway, is there a way to tell or should we do it in late September or Early October when we trim or prune them?

A. It is hard to give one broad generalization when to remove tree stakes for all situations. Much of that depends upon the condition of your tree when you bought it and how it was planted. One easy method that you can try to see if the tree or plant needs to be staked longer is to first remove the stake. Begin to bend the tree and watch the soil surrounding the trunk. Do this gently. As you bend the tree as if it were being blown by the wind, see if the soil moves around the trunk. A firmly rooted plant will not move the soil surrounding it or move it only slightly. If the soil moves excessively, replace the stake making sure the stake is driven deeply in the soil so it will not move. Tie the tree to the stake as low on the trunk as possible so that the top of the plant can move while its roots remain motionless. Water deeply to encourage root growth. By the end of this growing season your tree should be firmly rooted and you can remove the stake permanently. If you have done all this and it is not firmly rooted by the end of this season, there may have been something very wrong with the root system at the time you bought it. Tree roots that are pot bound or overgrown for the container may never firmly establish in the soil. Always select a plant that appears appropriately sized for its container. Avoid plants that appear large for their container. Even though these plants seem to be a "better deal", they never are. Those plants will be your future problems.

Q. Right now I have seven gardenia plants. Six are recommended for full sun and one is a shade gardenia. I don’t agree with you that they are difficult to grow. Two are almost three years old and the rest are 1 to 2 years old. They bloom like crazy in the spring and have lovely shiny green leaves the rest of the year. They are watered on the same schedule as the rest of the plants in my yard and I give them acid fertilizer in the spring and fall. Last year’s freeze did not injure them at all and they take the heat here also. I have had a wonderful experience growing them.

A. The problems that you will have with your gardenias will begin at about year four or five. Generally speaking, plants that are considered more acid loving frequently do well here (as long as you don’t throw in what are called the ericaceous plants, those that truly love highly acidic soils).

What I believe happens is that at the time of planting these plants are planted in ideal soil conditions. Frequently they are planted with plenty of compost, acid forming soil amendments and fertilizers and given prime care.

This soil environment usually deteriorates in about five years. At this time, the plentiful organic matter has decomposed to low levels in the previously rich soil. Now the surrounding desert soils begin to heavily influence the soil surrounding the roots. The deteriorating amended soil begins to revert back to our harsh (for plants like gardenias) desert soil.

The tap water (carrying one ton of salt for every 300,000 gallons) used for irrigations begins its inevitable impact on the soil surrounding the roots. Soil around the plant begins to compact when it was previously open for drainage. Water begins to drain more poorly.

Iron and a couple other plant nutrients sensitive to our soils start becoming less available to these plants. Root systems respond to these conditions by dying back. Yellowing leaves with green veins begin to appear on new growth. By the following year, leaves begin to scorch more easily and branches begin dying back. Increased susceptibility to stresses like heat is inevitable as plant health deteriorates due to poor nutrition. In following years these plants continue a slow decline and downward spiral.

We frequently see this happening with plants that are not as sensitive as gardenias to our soils. These nondesert plants, such as photinia, heavenly bamboo, mockorange, bottlebrush, and others, are commonly planted in rock mulches with more tolerant plants. The five year time frame generally holds true for most of them provided they are planted with amended soils at the start. If not, this series of events happens sooner. I am very happy you are trying them and I would hope that anyone who would like to grow gardenias here should have a chance at them. Gardenias have been sold in Las Vegas for decades but we seldom see any in town over a few years old.

In the meantime, I hope you use organic mulches around these plants and irrigate them so their roots are continually flushed of salts. Secondly, use acidifying agents when you can such as finely granulated sulfur, aluminum sulfate or soil drenches with phosphoric acid to counteract the buildup of alkalinity. Third use soil-applied iron chelates such as EDDHA annually in the spring and foliar applied iron fertilizers when needed.

I would very much like you to keep me posted on how they are doing over the next three to four years. I think you will have trouble down the road but enjoy them! If I am wrong, you will have to tell us how you grew them. If I am right, at least you can enjoy them for several years to come. You can’t lose either way!

Don’t miss my two electronic newsletters on gardening and growing fruit in Nevada. You can get them by emailing morrisr@unce.unr.edu with which newsletter you would like to receive!

The University of Nevada Cooperative Extension is an outreach arm of the University that extends unbiased, research-based knowledge from the University of Nevada—and other land-grant universities—to local communities. Educational programs are developed based on local needs, often in partnership with other agencies and volunteers. For more information about the University of Nevada Cooperative Extension, please visit the website at www.unce.unr.edu or call (702) 397-2604 or 346-7215.

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