How to grow asparagus: a commercial guide

Choose hybrids and crowns

All-male hybrids

Hybrid asparagus has better vigour, disease tolerance and yield. All-male hybrids do not produce seed, which avoids volunteer seedlings that become a weed problem. Examples named in the guide: Jersey Knight, Guelph Millennium (the industry standard), Guelph Eclipse, Guelph Equinox, Sequoia, Spartacus and Walker Deluxe. Order well in advance.¹

Crowns or seed

Some varieties are sold as one-year-old crowns; others only as seed, which crown growers turn into crowns. For field production use only one-year-old crowns. Ten- to fourteen-week-old seedling transplants can also be machine planted in spring or fall.¹

Clean material matters

Fusarium can be seed-borne. Source new plantings from blemish-free crowns produced in virgin soil, ideally from fields fumigated against it.¹

Prepare a deep, well-drained site

Soil and drainage

Select deep, well-drained sandy loam. Crown and root rot is promoted by acidic and poorly drained soil, and Phytophthora spear rot by excess irrigation and poor air circulation.¹

Lime early

Maintain pH 6.7–7.0 and, if possible, lime the year before planting.¹

Weeds first

Reduce perennial weeds with systemic broad-spectrum herbicides before planting; herbicide options are limited in the planting year.¹

Plant the crowns

Date and spacing

Transplant one-year crowns from April 15 to May 38 cm (15 in) 1.2–1.5 m (4–5 foot) rows, with in-row spacing that gives 34,600–37,070 crowns per ha (14,000–15,000 crowns per acre).¹

Furrow depth

Set crowns in 20 cm (8-inch) furrows in light soils and 12.5–15 cm (5–6 inch) furrows in heavy soils, then cover with 5–7.5 cm (2–3 inches) of soil. Cultivate when spears emerge and continue until the furrows are level at the end of the first season.¹

Starter fertility

Before planting apply 56 kg N/ha (50 lb N/acre), plus phosphorus and potassium by soil test, and plow it under. Add 34 kg P2O5/ha (30 lb P2O5 per acre) in the bottom of the trench.¹

Feed the established planting

Annual nitrogen

Each year before emergence apply 22–45 kg N/ha (20–40 lb N/acre) and incorporate lightly; after harvest ends apply 45–65 kg/ha (40–60 lb/acre). Total from fertilizer should be about 90 kg N/ha (80 lb N/acre). No more phosphorus is needed if pre-plant levels were adequate; apply potassium by soil test.¹

Weed control

After the first year a typical programme uses a long-residual pre-emergence herbicide before spears emerge and again after harvest and a clean mowing, with post-emergence products directed or shielded.¹

Ramp up the harvest slowly

Why

Roots are the “gas tank” of asparagus. Picked spears withdraw stored carbohydrate and do not pay it back through photosynthesis, so harvest ends to let ferns grow, make sugar and refill the crowns in fall.¹

Pick early in the morning, then protect the fern

Harvest early in the morning for best quality and let ferns grow vigorously afterwards. As much care should go into a healthy fern as into the harvest.¹

Avoid very long harvests

Long harvest periods weaken plants and favour crown rot over the years.¹

Scout for beetles and leaf diseases

Asparagus beetles

Adults overwinter in field debris and lay eggs on spears. At harvest treat when 5–10% of plants are infested or 2% of spears have eggs. In the fern stage treat when 10% of plants are defoliated or 50% have larvae. Regular harvest limits the eggs that survive.¹

Leaf diseases

Cercospora leaf spot is favoured by warm, humid conditions; remove or mow dead ferns in fall or winter. Purple spot (Stemphylium) and rust also occur.¹

Japanese beetle

It feeds on ferns through the season; control focuses on the adult stage after scouting the ferns.¹

What the numbers look like

US asparagus production in 2025 was 21,500 t (473,600 cwt) from 4,700 ha harvested (11,700 acres; 12,100 acres or about 4,900 ha planted), worth $66.5 million, up 41% on 2024. That works out to about 4.5 t/ha (40 cwt per acre) nationally; it is an average over establishing and mature fields, not a yield target.

Plan for a long payback

With no harvest in year 1, a trial in year 2, two weeks in year 3 and full harvest from year 5, cash flow is negative for several years. Model establishment cost, crown price and labour in the farm enterprise budget calculator before planting.^1,2

Frequently asked questions

How long does asparagus take to grow?

You plant one-year-old crowns, take no harvest in year 1, a trial in year 2, two weeks in year 3, four weeks in year 4 and a full season of about six weeks from year 5.

When do you plant asparagus crowns?

April 15 to May 15 in the Midwest guide, in 12.5–20 cm (5–8 inch) furrows covered with 5–7.5 cm (2–3 inches) of soil.

How far apart do you plant asparagus?

Rows 1.2–1.5 m (4–5 feet) apart with in-row spacing that gives 34,600–37,070 crowns per ha (14,000–15,000 crowns per acre).

What soil does asparagus need?

Deep, well-drained sandy loam at pH 6.7–7.0. Acidic and poorly drained soil promotes crown and root rot.

How much nitrogen does asparagus need?

About 56 kg N/ha (50 lb N/acre) before planting, then 22–45 kg/ha (20–40 lb/acre) before spears emerge and 45–65 kg/ha (40–60 lb/acre) after harvest each year, totalling about 90 kg N/ha (80 lb N/acre).

How long does an asparagus planting last?

The Midwest guide does not give a lifespan; the plan assumes full harvests from year 5 for as long as the crowns stay healthy, which depends on fern care, drainage and avoiding long harvests.