IT SHOULD COME AS NO SURPRISE, since it’s true so many other places still: In the asparagus rows, males are in charge. ‘Martha Washington’ and ‘Mary Washington’ were names you used to see most often in catalogs, but no more. Their weakness: The Washington strains include both male and female plants, and the males are far more productive if what you want is lots of spears. Who doesn’t?
In the mid-1980s, Rutgers University, a state institution in New Jersey, began a program to improve asparagus performance that focused on the extra productivity of the male plants. The resulting strains, most of which have the word Jersey in their names, are what you want to grow if you’re going to plant asparagus. They waste no time or energy on seed production and go right to the task of making spears. They can be harvested more often (about every two to three days in a productive, established bed) and yield about 20 to 30 percent higher than the old varieties.
But asparagus tests even the most committed gardener, asking for a major feat of excavation followed by a lot of patience. Whatever kind you’re planting, you have to dig a trench about 18 inches wide and 6-8 inches deep (some people go a foot deep). Since asparagus is best planted in spring, when dormant roots are sold by mail, prepare the bed the previous fall or in earliest spring. Order roots, or crowns, by mail for the freshest possible plants; they will be either one or two years old when you get them. Growers like Jersey Asparagus Farms will tell you which all-male variety is right for your region.
To prepare the bed, first test the soil pH by following the package instructions on a home test kit, or by taking a sample, according to their directions, to a local soil lab. The lab report will indicate how to amend the soil, and with what material; the typical routes are sulfur to acidify and lime to neutralize, but neither is a quick fix—or the whole answer. Adding large amounts of organic matter, preferably compost, to the soil should always be the first step; an organic soil is easier to pH-balance. For asparagus, you are aiming for a pH within the neutral range, or about 6.5 to 7.0.
As you dig the trench, put the soil you excavate on a tarp or in wheelbarrows beside the site. Then layer the middle of the trench floor with a few inches of well-rotted manure and soil, sprinkle with rock phosphate and an all-natural organic fertilizer according to label directions, tamp the bottom, then fan the dormant roots out over the mound in the trench so they look like so many giant spiders with legs dangling. The illustration from Cornell University, above, shows the “W furrow” that is created once soil or soil and rotted manure is shoveled or hoed into the middle of the trench to support the roots, after the roots have their first soil heaped on top, as below:
Space the crowns about 18 inches apart within the row, and leave a few feet between parallel rows. When they are in place, backfill an inch or two of soil onto the plants and firm, then water. Once the crowns send up green shoots, shovel in another thin layer of soil (don’t cover the tips completely), and repeat this step through the summer until the asparagus trench is filled back in. Keep the area weeded and watered.
Now comes the patient part. You cannot cut any spears until the third spring in the ground – a full two years after planting. (Sometimes cutting for just two weeks in the second year is suggested; follow the directions your grower encloses with your crowns.) Until then, simply let the plants go through their cycle of sprouting spears that turn ferny in summer. Don’t cut off any foliage until cleanup of the bed in late winter or early spring.
The payoff is obvious, if you love asparagus. And, best of all, if kept weed-free and otherwise well-tended, a planting can last for up to 20 years. Did I mention that you can also grow the super-sweet and exceptionally pretty purple-spear varieties at home (here’s one source)? Maybe food for another post…