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Plant of the Week: Blanched Asparagus

The University of Arkansas System Division of Agriculture does not promote, support or recommend plants featured in "Plant of the Week." Please consult your local Extension office for plants suitable for your region.

Plant of the Week

Blanched Asparagus
Latin: Asparagus officinalis

Picture of asparagus on dinner plate
White asparagus is produced by mounding sandy soil over the crown to exclude light in a process called blanching.

Rapid transportation, global trading and improvements in storage have eliminated seasonality from our table, making it possible to get almost any fruit or vegetable at any season. As an example of this, fresh white asparagus produced in Peru is in the stores this winter.

Americans favor green asparagus, whereas white (blanched) asparagus seems more popular in Europe. Blanching dates back to at least the 16th century when asparagus forced in cellars became popular with the rich aristocracy. The word “blanching” is also used in food preservation when vegetables are immersed in boiling water to kill the tissue. But in the gardening sense, blanching is used to describe growing plants in the dark.

Asparagus is a labor-intensive crop to produce and blanching requires more of it, so blanched spears cost about 15 percent more than the green form. Blanched plants have a slightly milder taste (some describe it as nuttier) than green asparagus.

Chlorophyll forms only in the presence of light so blanched plants must be grown in complete darkness. Asparagus farmers blanch their plants by piling sandy soil over the crown in late winter. Then, by careful daily or sometimes twice daily inspection, the spears are cut as the soil begins to crack open. Established plantings can be cut for four weeks.

Asparagus, blanched or not, has a dirty little secret never mentioned in polite company. It makes your urine stink. Not surprisingly, a socially taboo subject like the stinky smell of urine has attracted attention from a number of scientists who never quite outgrew their adolescent ways.

Since tackling this serious question, science has raised as many questions as it has answered. It appears that not everyone is afflicted by this malady. An English study suggests that about half of the population produces asparagus smelling urine while about 75 percent of Americans do.

The French, on the other hand, claim that everyone metabolizes asparagus to produce the odor, but that only part of the population have the smell receptors in the nose to detect it. This is obviously challenging research because many are reluctant to discuss their bathroom habits with complete strangers.

A sulfur containing compound called asparagusic acid appears to be the only compound unique to asparagus. While there’s still much debate about how this compound is metabolized, the best guess so far is that it breaks down into at least six volatile sulfur compounds that give rise to the smell that has been described as being like rotten cabbage. Of these compounds, methanethiol and dimethyl sulfide have been shown to produce a similar smelling concoction when added to water.

The smell reaction occurs quickly. Real asparagus urine aficionados use a stopwatch and report that the smell is present in about 15 minutes.

By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - March 3, 2006


The University of Arkansas Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.