Growing Asparagus

Karin Peterson
Adams County Master Gardener

It is May, and asparagus, one of spring’s most savory gifts, is at its peak. Whether steamed, stir-fried, roasted, wrapped in prosciutto or sauced with Hollandaise, asparagus fresh from the garden is as nutritious as it is delicious.

Used in both culinary and medicinal ways in ancient Egypt, its popularity spread to Europe, northern Africa and western Asia during the middle Ages. Introduced in the United States about 1850, this perennial vegetable favorite can be found growing anywhere where there is a cold or dry season (needed for its dormant period) in cultivated home gardens, as well as abandoned garden sites, old farm fields, fence rows and even roadsides, where birds have dropped seeds.

Seeds aside, asparagus (Asparagus, officianalis) is best and most easily grown from transplanted crowns, planted in early spring or late fall in rich, well-drained neutral to slightly alkaline sandy loam soil where it will receive ample full sunlight. Traditionally set in 12-inch deep trenches, 18 inches apart in rows 4 to 5 feet apart, asparagus prefers its own bed, as its roots spread laterally for several feet. There has been some success with the more recent method of planting crowns in a shallow furrow several inches or more below the soil surface; but for the uninitiated, best results most likely would follow with the traditional method. With the addition of a dressing of well-rotted manure or compost and watered to 8 inches once a week, all that’s needed from the gardener at this point is adequate patience. During its first spring, the spindly new stalks must be spared and allowed to "go to fern" or to mature to a ferny 39 to 59 inches in height.

Being dioecious, or having both male and female plants, the ferny asparagus may sport bright red berries on the female plants during fall, These berries are much appreciated by birds, but toxic to humans. In the fall, the ferny growth will turn brown, but it should not be cut down until the following spring, when spears will begin to emerge as early as April. When 6 to 8 inches tall, these spears may be harvested lightly for a period of about 2 weeks. It is during the third spring that patience begins to pay off, and the new chubby spears can be snapped off or cut at ground level for a period of 4 weeks. During the fourth and succeeding springs, the harvest may cover an 8-week time span. Given adequate sun, nutrients and water, a well-managed asparagus bed can be expected to produce well for 18 to 20 years.

Remember to mulch deeply after planting, but when spears emerge, remove all but a light covering to discourage lodging slugs. One other known pest, the asparagus beetle, can be controlled to an extent by companion planting with tomatoes, while the asparagus may repel certain harmful nematodes in tomato roots.

While green asparagus is most familiar and popular with gardeners and diners in our area, blanched, or white asparagus, created by hilling soil on the spears as they grow, is considered by many, especially in Europe, as gourmet and thought to be more tender. A more recent, purple cultivar, with a higher sugar content and lower fiber, is also available.

There are many reasons to grow your own fresh asparagus-- nutritional, medicinal and horticultural among them. A high fiber vegetable, asparagus is low in calories as well as in sodium and is a good source of vitamins B6, A, C, E and K. Add to that calcium magnesium and zinc. High in antioxidants, asparagus is also known as a natural diuretic and can be helpful in treating hypertension through its ability to restore an imbalance of the sodium-to-potassium ratio in the body.

As always, when selecting seed or crowns, it is best to purchase from reputable dealers who can be relied upon to carry treated seed and healthy stock. Untreated seed can result in plants prone to rust and fusarium rot. Some proven varieties in our region are Mary Washington, Rutgers Beacon and Waltham Washington.

With all its benefits, as well as its ferny beauty, consider asparagus in your garden.