Asparagus is undeniably one of the most anticipated crops at the farmers’ market. Bundles sell out early, usually purchased by giddy customers that show up well before the market opens. In the home garden, however, this same giddy anticipation can jeopardize future harvests.
With years of waiting ahead, beginning asparagus growers will want to be sure that they set themselves up for success from the beginning. Asparagus is a perennial crop with a lifespan of up to 15 years. When started from seed, is not harvested the first two years and only sparingly the third. Plantings that are harvested too soon or overharvested in any given year will likely never fully recover.
For long-term production, growers need to plant asparagus into a well-prepared site in full sun. To improve drainage and because asparagus is a heavy feeder, amend the soil with organic matter such as finished compost or aged manure before planting. Be sure to choose a site where asparagus has not been grown before. Asparagus is allelopathic, meaning it exudes chemicals that prevent the growth of surrounding plants, even other asparagus plants. It is also highly susceptible to Fusarium root rot, a common pathogen which remains in soil for up to seven years.
To provide time for the establishment of a healthy root system, plant asparagus crowns in May right after threat of frost. Disease resistant all-male hybrid varieties can be purchased from reputable dealers as crowns, one to two year old root systems. Asparagus crowns are typically shipped for planting in April or May.
Most small-scale growers prefer using the trench method of planting asparagus. After amending the soil and ensuring proper drainage, dig a 12 to 18 inch wide W-shaped trench down the length of a row. The trench may be anywhere from four to ten inches deep. In the W-shaped trench, place the asparagus crown slightly higher up in the middle, with the roots spread out into the lower parts of the trench. Plants may be spaced 12- to 18-inches apart within row and five to 6 feet between rows. Backfill the trench to cover two inches above the crown. As the plants grow continue backfilling a few inches at a time until the trench is full.
When deciding how deep to plant asparagus, consider market and family preferences. Shallow plantings, such as four inches deep, will produce earlier in the season, send up many smaller spears, and be more susceptible to frost. Deeper plantings will send up fewer and larger spears later in the season. The yield of the asparagus crop does not change, but planting depth will produce different style asparagus spears.
Planting asparagus is an investment, and growing a healthy, productive plot requires a hearty dose of patience and planning. After the initial planting, however, asparagus requires minimal maintenance and will produce for years to come.