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Asparagus (Asparagus officinalis)
by Carole Saville
When I eat asparagus, I always think of my neighbor, Mr. Tunis—volunteer fireman, school bus driver, jolly good fellow, and generous gardener—who stopped by one spring day in his red pickup truck and brought me an armful of asparagus crowns from his abundant garden. I was a rank beginner, digging my first garden in the shelter of the stone walls left from an old dairy barn in rural New Jersey. As an enthusiastic novice, I attributed my flourishing asparagus patch, which improved with every year, to the things I learned from the vegetable books I studiously read. In reality, my thriving plantation of asparagus probably owed a lot more to those thick stone walls, which warmed the elegant, green spears grown at their base.
Aside from the pleasure of harvesting your own, you get to watch the spears not cut for the table grow into delicate foliage plants with billowing ferny branches that may reach five feet in height. They make a handsome backdrop for a flower border and also look good planted sentry-style along a walkway. The female plants produce vivid red berries; the male plants do not. Though the female plants produce thicker spears, the male plants produce a larger number of them, since they don't have to expend their energy making fruit. These days, many gardeners are planting only the all-male or predominantly male hybrids, such as 'Jersey Giant' or 'UC 157', for a greater yield.
Starting an asparagus patch requires a bit of work intially, but it will stay productive for many years.
Asparagus, a winter-dormant, herbaceous perennial, grows well in most North American climate zones, with the exception of the coldest, the warmest, and the most humid areas. Traditionally, the "quickest" route to harvesting your own asparagus is to plant bare-root crowns in deep trenches, which will net you a small number of spears in the second year, followed by sizeable harvests after the third year. You can also start asparagus from seed, with a small harvest the third year and a full harvest in the fourth and each following year. Generally, gardeners purchase seed only of those varieties for which crowns are not available, such as the heirloom 'Argenteuil', a savory French asparagus with thick, handsome rosy-purple and green stalks.
Growing Asparagus
Diligence in the preparation of asparagus beds—and patience—are the initial requirements for enjoying harvests of the vegetable over many seasons to come. A heavy feeder, asparagus requires soil with a pH of 6.5 to 7 that is rich in organic matter and provides excellent drainage. As the asparagus beds can remain productive for ten years or more in the same place, it's vital to dig the patch deeply when you start. In early spring, choose a site in full sun and turn over the soil, removing all weeds and grass. Amend the soil with compost or well-aged manure, and add one pound of bonemeal or two pounds of rock phosphate for every 25 feet of row.
How much asparagus should you plant? The rule of thumb is that 30 to 40 crowns will suit a family of four. To prepare beds for that quantity, dig two trenches six to eight inches deep (or one foot deep in cold areas) and one foot wide, approximately 20 feet long, and three to four feet apart. Plant the crowns 15 inches apart, spreading their roots out in a circular fashion over a small mound of soil. Cover them with several inches of soil. As the shoots gradually break through the surface, keep filling the trench with soil until it reaches ground level, then spread four to six inches of an organic mulch, like salt hay, cocoa hulls, or fir or oak leaves, to help eliminate weeds, provide extra nutrients, and conserve moisture. The asparagus patch needs to be watered well during its first year but will require only moderate amounts of water during the following growing seasons. When the long-awaited day of the asparagus harvest arrives, cut six- to eight-inch spears on an angle just below the soil level and savor the rewards of your labor. Once the asparagus crowns are full-grown, the harvest season will last about six to eight weeks every year.
Rust and Cercospora leaf spot are diseases that plague asparagus, and the best approach is to plant varieties that have proven disease-resistant. Rust is associated with damp weather conditions, and Cercospora can invade asparagus in the Southeast. Consult a local nursery or your cooperative extension about which asparagus varieties are best adapted to your USDA zone. The asparagus beetle is a prevalent pest, but covering beds at planting time with floating row covers is an effective deterrent. If the beds are already infested, conduct a diligent fall cleanup, followed in early spring by hand-picking of the beetles, their larvae, and their eggs.
Recommended Varieties
With the exception of 'Argenteuil', an heirloom variety that needs to be started from seed, all the varieties mentioned in the following list are available as crowns.
'Argenteuil'—French heirloom; grown from seed; thick, rose-purple and whitish-green spears with excellent flavor. Traditional variety for blanching (white asparagus).
Once the asparagus crowns are full-grown, they will produce fresh spears, such as these purple ones, for about six to eight weeks every year.
'Jersey Giant'—Productive all-male hybrid; large succulent green spears with purple-tinted bracts; tolerant of rust, Fusarium wilt, and crown rot; good for colder climates.
'Jersey King'—Predominantly male hybrid, exceptionally large, tender spears with tight, round purplish bracts; widely adapted and resistant to rust, Fusarium wilt, and crown and root rot.
'Jersey Knight'—Vigorous all-male hybrid with large, bright green spears with purple tips; consistently high yields; widely adapted and highly resistant to rust, and tolerant of Fusarium wilt as well as crown and root rot; excellent disease resistance among the all-male hybrids.
'Mary Washington'—Heirloom; produces husky, straight, dark green spears with purple tinge on tightly folded tips; also good for canning or freezing; rust-resistant.
'Purple Passion'—Predominantly male hybrid; a European favorite with deep garnet, medium-size spears; very sweet and stringless; decorative in the garden but fades to green when cooked; however, the pretty purple slim young spears can be eaten raw or used as a garnish.
'UC 157'—Predominantly male hybrid; commercial variety developed for mild-winter areas of the Pacific coast, the Southwest, and the South; vigorous producer with large green spears of superb flavor; resistant to rust and tolerant of Fusarium wilt.
Eating Asparagus
Asparagus is an ancient vegetable, first cultivated by the Romans and used in such curious recipes as puréed asparagus tips simmered in white wine with onion, lovage, coriander, and savory, then thickened with egg yolks. If you don't want to go to all that trouble, fresh asparagus tastes fabulous briefly steamed and served with melted butter or as a salad with a vinaigrette drizzled over the vibrant green spears.
Carole Saville is a food and garden writer and author of Exotic Herbs (Henry Holt, 1997) as well as contributing editor to Country Living Gardener. She lives and gardens in the San Francisco Bay
area.Photos: David Cavagnaro, Derek Fell