White asparagus is green asparagus that is grown in the absence of light.
It’s the Same Vegetable
White asparagus is not a special cultivar of any specific plant variety. Any variety of asparagus can be grown either white or green. All varieties will start out white while they are growing beneath the soil surface, then they will turn green as they emerge from the subsoil and are exposed to sunlight.
Why Plants Turn Green in Sunlight
Photosynthesis is the process by which plants convert light energy to chemical energy. In this process, the plant absorbs light creating a chemical reaction that converts water and carbon dioxide to glucose that supplies nutrients to the plant.
Chlorophyll, a green pigment, is the part of the plant that is designed to absorb sunlight. Chlorophyll absorbs red and blue light thus making it appear green.
Do You Have to Grow White Asparagus Differently?
Because white asparagus will turn green if exposed to light, it must be grown in darkness. The process is called etiolation, which by strict dictionary definition means to alter the natural development of a green plant by excluding sunlight.
There are several ways that growers can accomplish this. One is to grow the asparagus underground by planting the asparagus deeper and mounding the soil higher. The asparagus grows in this manner underground and requires harvesting prior to emergence. If this method were not tricky enough, they then must be handled in the absence of light to keep them white.
An alternative method is to grow asparagus in created darkness, which can be done by using black plastic tunnels that completely seal the growing plant inside. This method presents several problems such as the retention of heat, which can be detrimental to the plant if it gets too high, as well as the issue of care, maintenance, and harvesting without exposing the plants to too much light.
Does It Taste Different?
The fact that white asparagus is considered a delicacy would suggest that there is a major difference between white and green asparagus when it comes to flavor. The general consensus seems to suggest that white asparagus is more mild.
The fact is, there are taste variations between two different green asparagus spears that were grown in different places. The flavor of any vegetable is contingent upon soil conditions, moisture levels, harvesting handling, and a variety of other factors. So in fact, one person may find white asparagus to be mild while another would find one grown in a different location bitter.
“Asparagus, Commercial Vegetable Production Guides, North Willamette Research and Extension Center.” Asparagus, Commercial Vegetable Production Guides, North Willamette Research and Extension Center. N.p., n.d. Web. 25 Feb. 2014. <http://nwrec.hort.oregonstate.edu/asparagu.html>.
“Photosynthesis.” UC Clermont College. N.p., n.d. Web. 24 Feb. 2014. <http://biology.clc.uc.edu/courses/bio104/photosyn.htm>.