Type your question here!

Saturday, January 12, 2019

Desert Horticulture Podcast: Citrus, Landscape Fabric, Lawn Failure

Join Bob Morris' Podcast on Desert Horticulture

This podcast includes discussions of questions posted previously on this blog.

The topics of this podcast are:
Why did my Meyers lemon not produce fruit this year
Why did my Lisbon lemon stop producing fruit when I planted it from a whiskey barrel?
Should I use landscape fabric when installing desert landscaping?
After 6 years of having a lawn, the homeowner gave up and replaced it with desert landscaping

January Freeze May Eliminate Some Citrus Fruit

           I know I will get questions sent to me why their lemon or grapefruit did not produce any fruit this year. They will say, “The tree grew great, but it didn’t produce any fruit!” We had a pretty good freeze in parts of the Valley recently. If your lemon tree or other citrus had flowers, or very small fruit at that time, then that’s why.

Freeze Tolerance of Flowers vs Tree

            Citrus, the entire tree itself, is tender to freezing temperatures in the first place. It’s considered subtropical. The most tolerance to freezing temperatures starts with kumquat, then Myers lemon, grapefruit, followed by some of the oranges, true lemons and finally limes. Freezing damage results in temperatures ranging from about 22° F to 32° F.
            As soon as growth begins, tolerance to freezing temperatures decreases in entire trees. This holds true of all fruit trees. There is no temperature discrimination when the tree is flowering. All fruit tree flowers and young fruit, whether they are apple or citrus, will die when it freezes. Freezing occurs at 32° F. No exception.
            All flowers are tender to freezing temperatures. All fruit trees flowering during freezing temperatures result in dead flowers and no fruit. The tree survives at 32° F, but the flowers don’t. Young fruit trees are more sensitive to cold temperatures than older ones.

Wind Makes Freezes Worse

            Add a light wind to this formula, flowers and fruit for that year are history. There is a debate whether plants succumb to “wind chill” like humans and animals. Let the debate rage. But I guarantee you, if there is wind associated with any freezing temperature, there is more damage than if there were no wind at all. Protect food production areas of the landscape from wind.
            You are lucky. If you don’t like a cold north wind, you go inside the house and get warm. Plants can’t. They must “suffer” through it. Therefore, let them occupy protected spaces in the landscape and they will be more productive and produce better quality food.

Arizona State University's citrus variety descriptions and harvest times.

            Remember, there are microclimates in a landscape. South and west sides are warmer locations than north and east sides of the home. Protect the tree from wind and you have a nice small, warm microclimate that produces better food.

Windbreak Establishment for Gardens in Pahrump, Nevada

Q. I am a recent transplant to Pahrump, Nevada, from Idaho where I was a master gardener. I have an acre property of bare dirt and want to plant all sorts of edibles from tree fruits to vegetables. But first I want to plant a windbreak around the perimeter of my property. I need some advice on how to start. 

A. As you will find out as you talk to more people in the Pahrump area and those that are gardening you will see the temperature in the winter time is one of your major limiting factors. Trees that do not survive below temperatures of 15 or even 10 degrees Fahrenheit during the winter time are not good choices for you so that might eliminate pomegranates, figs, etc.

The Windbreak

     Let's start with the windbreak. I would caution you about is planting a perimeter around your property for a Windbreak. I think some people are making a mistake when they do that with their property. I understand the reason for defining it with some sort of wall but I think that's the wrong approach if you are thinking about a Windbreak.

Diagram of a living windbreak. Area A is the area of competition and equal to about the same height as the plants in the windbreak. This is competition for sunlight, water, etc. B is the "quiet zone" and maybe 5 times the height of the windbreak or even more. This area is the best area for food crops. The overall effects from a windbreak could be up to 30 times it's height. 

    A key component of a windbreak is how much area it modifies. I would suggest for you that you determine which direction winds are coming from that are your primary problems. Put windbreaks as close to your growing area as possible. The most effective when brakes allow about 20% of the wind to penetrate it through and into the growing area. They don't block wind as much as they slow it so it decreases the damage.

     Buy  an inexpensive recording temperature device such as this Taylor instrument available on Amazon. You can get them for less than $15.

Consider Non-living Windbreaks int the Desert

     I would also suggest that you consider nonliving windbreaks around growing areas, particularly around the vegetable and Herb growing areas. These could be things like chain link fence with PVC slats throat through them if you want to put something up that's relatively expensive. Or it can be as simple as reed fencing.
     The area affected by the windbreak is about equal to 5 - 10 times its height. You can see that if you were to plant around your perimeter for a windbreak it won't be very effective because the distance is too far from the growing areas. Plus, if you were to grow big plants on the perimeter they are just going to use a lot more water than a nonliving or even a living when brake that's closer to the growing area. Plus nonliving windbreaks have a smaller area of competition.
     For sure, growing areas are more productive with better quality produce if they have a windbreak. But that windbreak should be as close to the growing area as possible if it's to be effective. Otherwise you're just growing plants on the perimeter of your property that don't do much good. And you have to water them.
     So I hope you will rethink the windbreak options that you would have on your property before you start investing in some plant materials and irrigation to support it. As far as growing during the growing season which is probably behind Las Vegas about 3 to 4 weeks.

Soil Amendments and Sun Shade Cloth in the Desert

     Some of your big problems in growing will will be the use of soil amendments more than you did an Idaho and learning when to irrigate at the right time.
     Sun protection may be a problem for some vegetables because the sunlight here is more intense than it was in Idaho. So some vegetables will perform better under light shade cloth, about 20 to 30% shade and no more than that.
     I will forward to you some contact information on some good growers in Pahrump and start picking their brain. Start with the Pahrump Farmers Market people and get to know them in particular Cherri and her group who are very active in the gardening community there.
     You can always send me some questions to verify some information or if you don't find the information you need. Pahrump have some pretty good soils compared to Las Vegas but that winter low temperature is a major barrier that you have to consider.