Recommended variety: Mary Washington
When to plant: Early spring is best, although winter planting is quite common in mild-winter areas.
How to plant: Asparagus thrives best in deep, loose, fertile soil prepared about 2 weeks before you plant the crowns. You need roughly 200 square feet for an asparagus bed containing 2 rows about 20 feet long set about 4 to 6 feet apart. This is a large enough space to accommodate between 30 and 40 plants, which is usually sufficient to supply a family of 4. Dig trenches 1 foot wide, 20 feet long, and 8 to 10 inches deep. Work from 3 to 6 inches of processed steer manure into about 6 inches of the soil in the bottom of the trench; then soak thoroughly. Set the asparagus crowns in the bottom of the trench so that the tops are between 6 and 8 inches below the top of the trench and the roots are spread out evenly. Space crowns about 12 inches apart and cover with 2 inches of loose, pulverized soil. Then water slowly and deeply.
As the young plants grow, fill in the trench little by little with loose soil, but don’t cover the tips. By summer, the trench will be completely filled. Water plants thoroughly every 7 to 10 days during the summer.
Because asparagus plants need at least 2 years to get established, you shouldn’t harvest any spears the first year; rather, allow them to make foliage. When the foliage turns brown in late fall or early winter, cut the stems to the ground. Never cut foliage back too soon – it manufactures food for the roots for about 6 months following the harvest period.
In early March of the second year, you’re ready to harvest your first asparagus crop. Cut spears for only 4 to 6 weeks, then allow the foliage to develop. From the third year on, you can harvest the crop for the full harvest period (8 to 10 weeks), or until spears become thin, indicating that food stored in the roots is about to be exhausted for the season.
Asparagus spears are ready to cut when they are about 6 to 8 inches long. However, some gardeners prefer the more delicate taste of spears only about 5 inches long. You can cut the spears at ground level, or a few inches below the soil, but you should not make any cuts closer than 2 inches from the crowns. To avoid possible injury to the crowns or to the new shoots that are developing below the ground, use an asparagus knife specially designed for the purpose.
At the start of the cutting season, you will probably be able to harvest some spears every 3 days. As weather warms up and spears appear more rapidly, you may have to harvest the spears once or even twice a day. In cold-winter areas, mulch with well rotted manure before the first frosts arrive to protect the root systems. Early each spring, cultivate and feed with a complete fertilizer.
Asparagus beetle, cutworms, earwigs, snails, and slugs are the chief enemies of asparagus. Infestations of asparagus beetle on spears during cutting season can be brought under control by spraying or dusting with rotenone or malathion (note label precautions). A spray containing Sevin may be applied to foliage after cutting season, for control of asparagus beetle, cutworms, and earwigs. Use bait to control snails and slugs.