by Jan Cashman
Growing up in Minnesota, my mother had me scrounging for wild asparagus behind our house near the railroad tracks, a duty I didn’t mind because asparagus was one of the few vegetables I liked as a child. All this wild asparagus in the Midwest might make you think that it is native to North America, but it is not. Cultivated in Asia and Europe for two thousand years, asparagus was considered a delicacy and prized for its medicinal properties. When the first Pilgrims came to the New World, they brought asparagus. They knew it was adaptable to various soils and, once established, a dependable, nutritious food so they included it in their earliest plantings. The pioneers brought asparagus with them as they moved west, and, over the centuries, birds have spread the seed throughout our nation’s woodlands and river bottoms.
Mary Washington, a hardy, strong, productive variety, has been the asparagus grown in northern climates for years. Recently, newer hybrids have been developed at Rutgers University, which are more vigorous, disease resistant, and higher yielding than Mary Washington. The researchers, in the hybridizing process, bred out most of the thin female seed stalks and left the thick male spears we like to eat. Because Rutgers is in New Jersey, each of these asparagus varieties has “Jersey” in their name (i.e. Jersey Knight, Jersey Giant).
Purple passion is a new hybrid available this year. Its tender spears are a beautiful, deep burgundy color but they turn green when cooked. Although I haven’t grown purple passion, the descriptions say it is more tender and sweet than other varieties and so vigorous the spears are ready to harvest a year earlier than most varieties.
Asparagus can be started from seed sown directly into your garden, however, most gardeners chose to start with two-year-old, bare root plants (called crowns) in early spring, giving them a two-year head start on seeds. Since an asparagus bed will be there for years, it pays to do plant it right. Locate your asparagus patch in your vegetable garden, probably near the edge because you cannot rototill this area after it is planted. The crowns need to be planted deep so dig a trench 12 inches wide and deep. Work several inches of organic matter such as compost or well-rotted manure into the bottom of the trench; then work Triple Superphosphate or bone meal into the compost.
Bare root asparagus crowns look like little octopuses. Spread the roots out onto small mounds you have made in the bottom if your trench 12 to 18″ apart. Do not fill in your trench with soil entirely right away, but barely cover the top of the crowns, and then, as the new sprouts emerge, cover them with your soil/compost mix until the trench is filled in to ground level. So all the plant’s energy can go to root development, don’t harvest your asparagus the first year, and sparingly the second. Once your asparagus bed is established, you can harvest into June. After that, let the spears go so they can store up for next year’s crop.
Asparagus, in gardener’s talk is, a “heavy feeder”, which means it needs plenty of fertilizer. Once-a-year fertilization in fall or early spring with a high phosphorous fertilizer such as 16-20-0-14 should be sufficient.
Weeds, especially grass, can be a problem in your asparagus patch because you cannot rototill nor can you use most herbicides when the plants are up or they might harm the asparagus. The preemergent herbicide Preen can be applied in early spring to contain weeds, but avoid preemergents such as Casaron that could harm to spears as they emerge. Grass Getter, a postemergence grass herbicide, is safe to use on asparagus. Sometimes during the summer we spray Roundup near our asparagus row, being careful to keep it a safe distance away. A thick mulch over weed-free ground, and diligence in pulling the weeds as soon as they come up is probably the best way to deter weeds.
Asparagus is not particularly prone to insects or diseases. Since it is a crop you are harvesting in April and May, frost can damage the new tender spears. My solution to this frost danger is to pick all that is up if a hard frost is forecast.
Leave your asparagus fronds standing over the winter to catch insulating snow; then cut the fronds down in the spring. Extra mulch on your asparagus patch in the winter is probably not necessary if you have a winter-hardy asparagus variety.
Fresh asparagus is my favorite vegetable-there is nothing better than picking (cut spears off slightly above ground level with a sharp knife or scissors, don’t pull them) a bunch and cooking it for dinner. If your patch provides more than you can eat, asparagus freezes well. April is the ideal time to get asparagus started, along with perennial fruit crops like raspberries and strawberries. Plant now and enjoy for years to come.