For Its Investment, Asparagus Offers Good Rate Of Return

Hardy Perennial Is The Garden's First Bounty That Lasts

April 26, 1992|By Dave Glassman | Dave Glassman,Contributing writer

Home-grown asparagus is the vegetable world's equivalent of a set ofreplacement windows. It costs a lot to install, but the benefits canbe enjoyed for years with a minimum of maintenance.

You know the adage about making your bed and lying in it? Well, you've got to makean asparagus bed for the plants to lie in for about 20 years. If youdo it right, they'll keep producing the best asparagus you've ever tasted.

And asparagus, a hardy perennial, is the first bounty to be harvested each spring. Even better, it doesn't all come at once in a fearsome onslaught of green spears, but can be harvested for 8-10 weeks when it's established.

You're probably wondering, "How do I get started?"

"The first thing is to choose a site," said Mary Jefferson, a professional horticulturist and a buyer at Metzler's Nursery in Columbia.

"You need a location with full sun, well-drained soil and no competition from trees or shrubs. You should realize it's a perennial that will be there for 15-20 years. In the summer the foliage grows six feet tall. It makes a wonderful screen, but don't plant anything shorter behind it or you won't see it. Make sure your soil preparation is done very well."

"Soil preparation" is a fancy horticultural term for bed-making. There are two ways to bed down your asparagus:in a trench or in a raised bed, but both require that the plants have good drainage below them. And, because asparagus roots like to spread out forming a thick mat, there should be plenty of room for them to do so. Any trench should be about 18 inches wide and 12-18 inches long.

Raised beds require similar minimum dimensions.

If you're using a trench, "Dig at least 12 inches, then backfill four inches" with sand, organic material and garden dirt mixed 1:1:1, Jefferson said. The organic matter can be composted bark, manure or yard compost, she said. She doesn't recommend using peat moss.

For planting in araised bed, "I'd work the soil maybe four inches below the ground level so the root system can penetrate," she said. "I'd mix organic matter and sand in."

Now you're ready to plant. "I think I'd go with root crowns because you get results -- a harvest -- faster," than with seed, Jefferson said. Root crowns are already grown from seed and are available from mail-order houses and nurseries. They may be dried and require soaking before laying them down, but a nursery should keep them moist in soil, ready to plant immediately.

To avoid delay and possible injury to a healthy root crown, "You should prepare the bed first, then buy the plants and put them in immediately," she said.

The Washington varieties have proven to be disease-resistant producers over the years. Now, the New Jersey varieties are coming into the market. They were supposed to be all-male hybrids but, because of breeding problems, turned out to be mixed. Male asparagus plants are hardier and yield more than females because they don't devote energy to seed production. The Jersey Knight variety, which Jefferson has ordered for Metzler's, is said to have eluded the breeding errors.

After the crowns have been laid out, cover them completely with an inch or two of soil mixture and keep moist. As the stalks begin to pop up, continue covering lightly with more soil mixture (with plenty of organic material) until your trench is filled in or the bed is raised six inches over the crown.

Now comes the hardest part.

If patience is supposed to be a virtue, growing asparagus proves it. The reward for your shoveling and mixing won't come for at least a year. The stalks must be allowed to grow the first year unharvested into tall, feathery ferns gathering energy for the crowns through photosynthesis.

After that it's dealer's choice. The traditional school of thought subscribes to the 2,4,8 theory. That says cut for two weeks the second year, four weeks the third year and eight weeks thereafter. Somerecent research concludes that no limits need be set in the second and third years; just harvest, at about 6-8 inches tall, until the stalks become too thin.

"My grandfather would never harvest unless itwas at least the size of your pinky," Jefferson said.

Since pinkies are as varied as the people they're attached to, some use other guidelines, like the thickness of a pencil. Personally, I cut all of them because it can be hard to find and safely cut the new stalks underdense foliage. In any case, harvesting must stop in early to mid-June so that the plants may replenish themselves for the next year.

"Asparagus likes phosphates," Jefferson said, so she recommends using a little 5-10-10. And a light mulch "keeps the moisture in, the weedsdown and makes the bed look attractive."

A shredded mulch, straw or manure would work well. If the soil level gets lower over the years, just add some more mixture, and each spring remove the previous year's growth which has died back before the new crop appears. Then carefully remove any weeds and you're ready to harvest again.


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