Fresh asparagus can be one of the early pleasures of a spring vegetable garden. While it takes a few years to establish a vigorous and harvestable asparagus patch, the reward is worth the wait, and the patch will continue to provide new spears for as long as fifteen years.

Asparagus has been cultivated for over two-thousand years, and is thought of originated between the eastern Mediterranean and the Caucasus mountains. Among the few perennial vegetables grown in the garden, Asparagus officinalis was once grouped in the large plant family called the Liliaceae (lily family), but is now grouped into its own taxonomic family, the Asparagaceae. Unlike most plants, asparagus is dioecious, meaning it has separate male and female plants rather than bisexual plants or flowers. Different asparagus varieties are therefore either male or female. The variety ‘Mary Washington’ is a common heirloom variety that is female. Newer male hybrids, such as ‘Jersey Gem,’ ‘Jersey Knight,’ and the sweeter purple-speared varieties like ‘Purple Passion’ tend to produce more, if smaller, spears.

Asparagus is planted as a crown, which consists of a rhizome (underground horizontal stem), fibrous roots for water and nutrient uptake, fleshy roots for energy storage, and a cluster of buds. We eat the young, tender stems (called ‘spears’) that emerge from these buds. The small, scale-like leaves on the side of spears are the only true leaves. If left unharvested, from these buds emerge stems called cladophylls that look superficially like fern leaves. The cladophylls function like regular leaves however, absorbing sunlight and carbon dioxide for photosynthesis and evaporating water for transpiration.

Asparagus grow best in deep, fertile, well-drained soils with a pH of 6.0-6.7. Heavy clay soils should be amended with organic matter, otherwise the spears may not emerge straight. Alternatively, asparagus patches do great in raised beds. Have your soil tested through the N.C. Department of Agriculture & Consumer Services’ soil lab; test kits are available at your local N.C. Cooperative Extension Center. Whereas soils sampled for most vegetables are taken six inches deep, soils beds intended for asparagus should be sampled at a depth of twelve inches.

Disease-free, one-year old crowns should be purchased from reputable nurseries. Asparagus can be planted from mid-February through March in central North Carolina. Space crowns twelve inches apart in rows five feet apart. Plant crowns in eight-inch deep furrows, with buds pointing up. Cover crowns in two inches of soil, then add additional soil as the spears grow until the trench is filled.

Next comes the hard part: patience. Do not harvest spears in the first year! It takes at least two full growing seasons for asparagus plants to develop enough of a storage root system and energy reserves to be able to tolerate the harvest of new stems and the growth of other stems needed for photosynthesis. Once the plants are three years old, spears can be cut just above ground level for six to eight weeks each year. After that, spears should bel allowed to grow through the rest of the growing season.

Matt Jones is Horticulture Agent for North Carolina Cooperative Extension in Lee County.