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Wednesday - July 24, 2013

From: Mesa, AZ
Region: Southwest
Topic: Diseases and Disorders, Transplants, Cacti and Succulents
Title: Soaptree yucca falling over in Mesa AZ
Answered by: Barbara Medford

QUESTION:

My soaptree yucca is about 5 ft tall and has fallen over. Does this plant require staking for I thought not, or is something else going on with it?

ANSWER:

This USDA Plant Profile Map shows that Yucca elata (Soaptree yucca) is native to Maricopa County, AZ, so hopefully that rules out the plant being in the wrong environment. By following the link above to our webpage on this plant, you will learn that it can grow from 5 to 25 ft. tall, and there is no mention of it bending over. One of the pictures from our Image Gallery below shows a Soaptree yucca which looks to be about 5 ft. tall. Here are the growing conditions for this succulent:

"Growing Conditions

Water Use: Low
Light Requirement: Sun
Soil Moisture: Dry
CaCO3 Tolerance: High
Cold Tolerant: yes
Soil Description: Well-drained soils. Gypseous, Sandy, Sandy Loam, Medium Loam.

Conditions Comments: State flower of New Mexico."

Two of those conditions that we would emphasize is that it needs "Sun" which we consider to be 6 hours or more of sun a day and the requirement for well-drained sandy soils. However, we think we may have finally found a possible answer to your question. If this yucca was transplanted into the spot where it is growing now, you should read this article by the USDA Forest Services on Yucca elata (Soaptree yucca):

"Soaptree yucca is difficult to transplant. Campbell and Keller reported that only 25% of soaptree yucca transplants survived due to taproot breakage. Soaptree yucca has been transplanted to revegetate highway rights-of way, but there was great expense in removing entire roots, as is required for successful planting. Successful transplanting of yuccas (an unspecified amount of which were soaptree yucca) has been done; plants were removed with as little root damage as possible and immediately watered when replanted."

Apparently the Soaptree yucca is rooted by rhizomes (like the underground roots of some grasses).

From the same article:

"Like all yucca species with dehiscent fruits, soaptree yucca is rhizomatous. The species is unique in that the rhizome develops downward and later begins lateral root extensions. The "vertical rhizome" as described by Webber commonly grows to 3-5 feet (1-1.5 m) deep, and 3-6 inches (8-15 cm) in diameter. Lateral roots are 6-10 inches (15-20 cm) long and 1-3 inches (2.5-8 cm) in diameter."

We can only assume that some of the rhizomes were damaged or destroyed in transplanting and, like a great tree blown down in a hurricane, the supports simply failed. If our supposition is true, we frankly see no remedy. The plant cannot live long on its side.

From the Image Gallery

Soaptree yucca
Yucca elata