Preparing for Asparagus
Time to turn your attention to asparagus. One of spring’s earliest crops, asparagus is typically ready for cutting in Maryland between April 25 and June 15.
If your bed is already planted, it needs prepping. Winter weeds have most likely covered the beds, and the old asparagus stems are still sticking above ground. While the soil is still cool, asparagus roots are not yet energized. As soon as the soil dries sufficiently so it will not clump on the hoe or tiller, adjust the cultivator or tiller so that the blades will not penetrate the soil more that two inches. Cultivate or till weeds and those old asparagus stems into the soil. Allow the soil to dry for at least a week, then repeat. Cultivating the soil will hasten its warming, which will hasten the sprouting of asparagus stems.
If you wish to delay the emergence of asparagus spears, cover the cultivated beds with four to six inches of straw. The straw mulch will shade the soil, retarding warming.
Under normal conditions, asparagus beds should not be fertilized or mulched with compost until after harvesting. But they should be kept weed-free. Hand weed with a hoe immediately after making a harvest of spears.
If you’re starting a new asparagus bed, now is the time. Choose a full-sun spot with well-drained soil. Dig a trench 10 to 12 inches wide and eight to 10 inches deep. Place one to two inches of compost in the bottom of the trench, and spade the compost into the soil to a depth of four inches.
Place the asparagus crowns over the spaded soil at eight-inch intervals, spreading the roots uniformly flat. Cover with about two inches of soil amended 1-to-1 with compost. As the asparagus spears begin to grow, continue adding amended soil to the trench until it is full.
Do not harvest any asparagus spears for at least two years. Allow the foliage to grow to its maximum height, cutting the stems to the ground in late fall when they have completely turned golden-brown. By delaying cutting, you allow residual nutrients in the stems and leaves to return to the roots.
After you have cut the asparagus back to the ground in the fall, mulch the bed with a two-inch-thick layer of compost. This not only helps to insulate the bed, it also supplies all the nutrients for next year.
In the third year, you may start harvesting asparagus spears in the spring. During the first year of harvesting, you should limit your harvests to two. For maximum recovery, cut the asparagus spears just below the surface of the soil using a sharp knife.
If you prefer eating French-style asparagus, white spears, build a low frame, 10 inches to a foot high above a section of your asparagus bed and cover it with black plastic. The same wire hoops used for building small tunnels can be used to support the black plastic. To prevent heat build-up, leave both ends of the tunnel partially open. Asparagus that develops in total darkness will be white and tends to be tenderer than green asparagus.
Ask Dr. Gouin your questions at [email protected]. Please include your name and address.