What Is White Asparagus – How Does White Asparagus Grow

What is white asparagus? Perhaps you've enjoyed this European delicacy in fancy restaurants and found the mild, nutty flavor more appealing than the grassy, bitter taste of green asparagus. If so, you probably want white asparagus growing in your garden, but here's the real head-scratcher. There are no varieties of white asparagus! So how does white asparagus grow?

What is White Asparagus

If you've ever watched seedlings sprout on a wet paper towel, you've probably noticed the stems are white and the leaves are pale yellow. These sprouts aren't green because they have not begun producing chlorophyll, which is the green pigment that gives herbaceous plants their color. 

Some plants, like asparagus, won't produce chlorophyll until they've been exposed to sunlight. So what is white asparagus? It's simple: Asparagus shoots which haven't seen the light of day. Any variety of green asparagus can be deprived of sunlight to produce white asparagus shoots.

How to Grow White Asparagus

Before you can have white asparagus growing in your garden, you must first establish healthy asparagus crowns which are at least three years old. Follow recommended guidelines for prepping soil, planting, and fertilizing asparagus for the first two years. 

White asparagus care can then begin in early spring of the third year. By this time, you should have a reasonable expectation of when asparagus will begin emerging from the ground in your area. Prior to this date, set up a method for blocking the sunlight from the emerging asparagus shoots:

• Soil mound – Pile 6 inches (15 cm.) of loose soil where the asparagus shoots are expected to emerge. A frame built of 6 inch (15 cm.) boards can be placed around the asparagus bed to keep the soil in place. When you see the shoots begin to push the soil upward, you'll know it's time to harvest. Carefully dig around each shoot and snap it off beneath the soil level.
• Black plastic tunnel – This method works well if you have unused row covers which can easily be covered with black plastic. There's no digging with this method and the asparagus shoots stay much cleaner, but excess heat generated underneath the black plastic may be problematic. If so, try substituting breathable black fabric for the plastic.
• Plastic tubs – Dark-colored totes can also be used to block the sun's rays. These are easy to lift off for harvesting, but will need to be secured on windy days. This may not be a cost-effective method for producing larger beds of white asparagus.
• PVC pipe – If you can detect where an asparagus shoot is ready to emerge, a section of PVC pipe can be placed over the soon-to-sprout asparagus plant. Push the pipe into the soil, then close off the pipe with a PVC cap to block sunlight. This method is simple and quick if you only want a few spears of white asparagus growing in the garden.
• Wooden Box – Craft a wooden box with a hinged lid and place this over the asparagus bed. Wooden boxes tend to be heavy, but are ideal in areas where high winds are an issue.