Trellised vines make good wind blocks
Q: I was hoping to put up a nice strong wind and sun block on the west and southwest corner of our front yard, approximately 20 feet each way. Could you give me some suggestions? I’ve talked to the neighbor on that side and we were thinking probably some kind of large bush.
A: Windbreaks and screens for sunlight in the desert are usually best if they are close to the affected area. The reason is that plants used for screening or deflecting wind have to be pretty big to do any good when they are far away.
Larger plants require more water. If you put a windbreak close to the area where wind is a problem, then you can use smaller windbreaks and smaller plants to achieve the same thing. If wind or sun is a problem all year long, then you would select evergreen plants.
If this problem is seasonal, you would select deciduous plants that drop their leaves in the fall and allow wind or sun through during winter months.
A general rule of thumb is that wind is affected on the downwind side of a windbreak from five to eight times its height, depending on the type and direction of winds.
To be effective, windbreaks made from plants should be at least two layers thick. The majority of wind will be diverted over the top, under the bottom and around the sides of windbreaks. Wind that does go through a porous windbreak will be slowed. How much it is slowed depends on how porous the windbreak is. Try to achieve about 20 percent porosity. This lets wind through it, slows it and decreases the amount diverted up or around a windbreak.
In the desert, think about structures to do this more than plants. These structures would be things like walls or trellises that can be covered with vines rather than large plants. A vine covering a wall or trellis will use far less water than plants the size and density needed to reduce wind speed and sunlight.
Also, using a structure and vines or small shrubs in combination will achieve a more permanent solution to the problem and occupy less space in small residential landscapes. Avoid wood structures that crack in our dry heat. Instead use cement and metal options that are more resistant to our harsh environment.
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