Plant and Harvest Asparagus in Early Spring

Home gardeners anxious to enjoy their first spring crop can plant asparagus--a cool-season vegetable that's one of the earliest to emerge in the spring garden.

Asparagus is a perennial crop that can remain productive for years, so selecting the bed site is important. Asparagus grows best in well-drained, sandy loam soil.

Before planting, apply one pound of super phosphate (0-46-0) and a half-pound of urea (46-0-0) per 100 square feet. (These numbers, found on all fertilizer bags, represent percentages of nitrogen, phosphorus and potassium.) Mix in fertilizers to a depth of 4 to 6 inches with a rototiller. Alternatively, gardeners can apply a complete fertilizer like 5-10-10 (4.5 pounds per 100 square feet), particularly if soil is low in potassium.

Make furrows 1 foot deep and 4 to 5 feet apart. Fill furrows back up with compost and fertilizer until they are 6 inches deep. Plant dormant, year-old asparagus crowns 12 to 18 inches apart in the furrow with buds facing up. Crowns can be purchased through most vegetable seed catalogs or in local nurseries.

Spread crown roots out evenly in the furrow covering both the roots and crowns with a couple of inches of soil and compost. Irrigate immediately. As spears emerge, allow them to develop into ferns, which can grow 4 to 6 feet tall. Do not harvest spears the first year to give them a chance to develop a strong root system for next year's crop.

Gradually fill in the furrow with soil and compost as the ferns develop, being careful not to cover the foliage with soil. Use furrows formed on both sides of the new asparagus bed for irrigation. In July, apply a side dressing of nitrogen fertilizer, incorporating the fertilizer into the sides of the bed and irrigating.

Early next spring, remove the old ferns and side dress with a complete fertilizer like 5-10-10 by incorporating it into the sides of the beds around the plants and irrigating.

Spears that emerge the second spring can be snapped off near the ground when they reach 6 to 8 inches long with tight buds. Stop harvesting when the average diameter of the spears is less than one-fourth of an inch. Fertilize and allow ferns to develop so that new food reserves can be restored to the roots for next year's crop.

When selecting varieties, look for all-male hybrids like "Jersey Giant", "Jersey Knight" and "Jersey King". All-male hybrids will out produce older varieties like "Mary Washington", which have both male and female plants. Female plants produce seed, reducing energy that would normally be devoted to spear production.

For more information, please visit New Mexico State University's Cooperative Extension Service (CES) Publications website.