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Tuesday, April 2, 2013

Saguaro Leaning and How to Correct It


Q. I have a saguaro cactus with three big arms growing from it leaning toward the west. On the east is my house and shading the cactus from the morning sun. I also have been watering on the house side of the saguaro, the up slope side, and letting the water run downhill into the roots.  I water about 3 or 4 times a year and water very slowly.

Do you have any suggestions about either stopping the continued leaning or how to straighten the cactus to upright?  Those two large saguaros have been in my yard for 17 years.

Saguaro leaning due to shade from the house most likely
A. These Sonoran desert monsters are top heavy. The root system of the saguaro is fairly shallow but expansive. This extensive but shallow root system can give this top-heavy cactus quite a bit of support under native desert conditions. But they have been known to blow over in high winds.

These cacti, like most, are opportunists and take shallow water from the soil before it evaporates or taken by neighboring plants. Most of the roots away from the trunk can be found at depths less than 12 inches. Watering deeply around these plants is probably a waste of water.

We put these plants in artificial desert landscapes and put them on drip emitters or run water close to the trunk. This can lead to a very small but dense root system close to the trunk. The roots don’t have to grow far from the trunk for water and so doesn’t help to stabilize the plant as the top gets bigger.

Saguaro normally does not need to be staked when transplanted but here is one method that protects the trunk
Your cactus could be leaning either because of the shade from the house or it might be leaning due to poor root support or both. If it is leaning and there is danger it will fall over then you will have to support it.

In the meantime, we create a more expansive root system by placing enough other desert plants close to this plant so that the irrigations from these other plants can help the saguaro extend its root system further from the trunk.

We could sprinkle irrigate the area around the saguaro, simulating desert rainfall. But sprinkler irrigation can lead to weed invasion in the landscape and weed control problems.

From the pictures you sent, obviously your watering regime has given your saguaro some good growth but it sounds like the water is concentrated close to the trunk. I will post the pictures of your saguaro on my blog for others to see.

Another possibility that could contribute to the leaning is how it was planted. If a hole was dug just large enough for the transplanted roots, and the soil was not conditioned properly, then this will encourage the plant to grow roots close to the trunk as well.

All cacti grow better in amended soils than in straight desert soils or sand. Always amend soils for cacti at planting time.

What can you do now? If the plant is leaning due to the house there is not much you can do. To give it better support put irrigation water at greater distances from the plant and use shallower irrigations.

Like I said, giving saguaro deep watering is not going to help but getting its roots to grow wider might. If the soil is not loosened, it is best to loosen the soil surrounding the plant where you are watering to encourage growth at distances that will support top growth.

2 comments:

  1. We have a 15 foot high saguaro that leans heavily, about 35 degrees, from half way up. It has a number of nest holes as well, and we fear it will fall soon. Do you recommend removal? I would like to attach a photo.

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    1. The usual reason for saguaro to begin leaning after several years is because the roots have not spread far enough horizontally into the soil. Frequently homeowners will put a few drip emitters close to the base of the plant. Saguaro roots in the desert extend a number of feet from the trunk so that it will remain stabilized. If it has its roots close to the trunk and it gets tall and heavy, it will begin to lean because it does not have the support needed. It is important for these taller plants to have many other desert plants that receive irrigation scattered within a few feet of the trunk. The roots will follow these irrigated areas where there are plants. Do not plant saguaro all by itself with water close to the trunk.It is difficult to tell you if you should remove it or support it until you get its roots growing at greater distances from the trunk. Certainly as the plant gets taller and heavier, it will fall over. Your call on it.

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