Asparagus is one of the most popular vegetables in spring. If planted in a favorable site and given proper care, an asparagus planting should produce good crops for 15 to 20 years.
Asparagus performs best in well-drained soils in full sun. Avoid poorly drained, wet sites. Phytophthora crown rot can be a problem in poorly drained, wet locations. Raised beds are a good planting option for gardeners with poorly drained soils. Planting sites should receive at least 6 hours of direct sun each day. Avoid shady sites near trees. A location at the end of the vegetable garden (that doesn’t interfere with annual garden tillage and other cultural practices) is a good site for many home gardeners.
Asparagus is dioecious. Dioecious plants produce separate male and female plants. Male asparagus plants live longer and are more productive than female plants. Excellent predominantly male asparagus cultivars include ‘Jersey Giant,’ ‘Jersey Knight,’ ‘Jersey King,’ and ‘Jersey Supreme.’ ‘Mary Washington’ and ‘Martha Washington’ are good standard asparagus cultivars. (A planting of ‘Mary Washington’ or ‘Martha Washington’ has an equal number of male and female plants.) ‘Purple Passion’ and ‘Sweet Purple’ are unique cultivars with deep burgundy or purple shears. (The spears of ‘Purple Passion’ and ‘Sweet Purple’ turn green when cooked.)
Early spring is the best time to plant asparagus in Iowa. Asparagus crowns should be planted in shallow trenches or furrows. The planting depth depends on the soil type. Asparagus crowns should be planted 8 to 10 inches deep in light, sandy soils, but only 6 to 8 inches deep in heavier soils. A small amount of well-rotted barnyard manure can be worked into the soil at the bottom of the trench before planting. Space crowns 12 to 18 inches apart in rows that are 4 to 5 feet apart. Spread out the roots in the trench with the buds pointing upward. After planting, completely fill in the trench with soil. (Though a common practice in the past, it is not necessary to gradually fill in the furrow as the plants grow.)
After planting, asparagus should be allowed to become well established before any spears are harvested. Do not harvest asparagus for the first two years after planting. Asparagus can be harvested until early to mid-June in the third and following years.
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