Asparagus is a hardy perennial vegetable that lasts up to two or three decades in a planned and well-maintained garden, according to University of Illinois Extension. Proper care for asparagus includes annual fertilization with the best type of fertilizer.
Phosphorous fertilizer, added to the soil before planting, encourages healthy root development of asparagus, according to the Arizona Cooperative Extension.
A balanced fertilizer works best for asparagus in the early spring, before shoots emerge, according to the Iowa State University Extension. Nitrogen fertilizer works best when applied in June after harvesting ends. Just 0.10 pounds of pure nitrogen covers a 100-square-foot area.
Manure or other organic fertilizer choices such as blood or bone meal and wood ash also work well as asparagus fertilizer, according to the Purdue University Extension.