Asparagus
Asparagus officinalis. ASPARAGACEAE.
Planting, Growing, and Harvesting Asparagus
You’ll find everything you need to know to plant and grow asparagus in the accompanying table’s tabs:
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- How many asparagus to plant
- Growing conditions for asparagus
- When to plant asparagus
- How to plant asparagus
- Watering, fertilizing, and pruning asparagus
- Companion plantings for asparagus
- How to harvest, store, and use asparagus
Growing Asparagus
Asparagus is a cool-season perennial. This member of the lily family is a prized, early-spring delicacy. Plants grown from seed require 3 years to become established and will produce spears but yield ample harvests annually for 20 or more years. The edible green female spears are capped with a bud-forming top; allowed to go to seed, the buds will sprout feathery, fernlike foliage.
Asparagus Plant and Care Guide
How Much to Plant
Allow 10–15 plants per household member.
How to Plant
Plant either seed or transplant root crowns.
Indoor Starts. Seed germinates in 14–21 days. Sow seed indoors in flats 12–14 weeks before last expected frost, grow to 3–4 in. (7.5–10 cm) tall and harden seedlings 7–10 days before transplanting. Transplant seedlings outdoors when soil warms to 50–85°F (10–29°C).
Direct Sowing. Sow seed in garden soil after soil warms to 50–85°F (10–29°C). Sow seed 1-1/2-in. (38-mm) deep, 2 in. (50 mm) apart, thinning to 6 in. (15 cm) apart, in rows 2 ft. (60 cm) apart.
Transplants. Alternatively, plant root crowns in late winter or early spring for annual harvests beginning in the second season. Plant crowns 18 in. (45 cm) apart, in trenches 1 ft. (30 cm) deep, backfilled with organic compost until 8 in. (20 cm) deep. Bury crowns with a layer of soil 2 in. (50 mm) deep, adding more soil over the plants in spring as their spears emerge, gradually filling the trench.
Best Conditions for Growth
Growing temperature: 60–85°F (16–29°C). Zones 3–10. Shade plants in full sunlight at temperatures over 95°F (35°C) to prevent bolting.
Soil Type and Fertility
Moist, well-drained soil. Fertility: Rich. 6.0–6.8 pH. Prepare soil at least 1 ft. (30 cm) deep.
Proper Care
Challenging. Keep evenly moist. Apply ample water during the so-called “fern stage.” Fertilize in early spring and after harvest with 10–5–5 formula supplemented with garden lime. Mulch. Cultivate.
Cut back feathery foliage to 1 in. (25 mm) above soil when it turns brown. Mulch heavily in cold-winter climates to protect root crowns from freezing and frost heaving.
To grow white spears, blanch asparagus by covering the bed with black plastic supported at least 12 in. (30 cm) high on stakes before spears emerge.
Rodent susceptible. Insect pest and disease resistant.
Pairing Recommendations
Artichokes, basil, parsley, and tomatoes.
Maturity, Picking and Gathering
Spring of third season, then annually. Avoid harvesting asparagus spears during first two seasons until root crowns are established and have multiplied.
Thereafter, harvest each season in spring. Plants produces thin male and stout female shoots for 4–6 weeks in spring. Cut only female spears when they are 1–4‑1/2‑in. (2.5–11.4‑cm) in diameter and up to 10 in. (25 cm) tall.
How to Store and Preserve
Fresh in vegetable keeper of refrigerator for 2–3 weeks; blanched and frozen, 4–6 months; pickled or canned, 1–2 years.
Steam or grill until tender. Avoid using metal utensils that discolors asparagus. Avoid salting water used for cooking to retain asparagus’ bright green color; cook, then chill in an ice-water bath.