How-To: Grow Asparagus

How-To: Grow Asparagus

Asparagus has been considered a garden delicacy since Roman times. Any home gardener can grow and enjoy this spring vegetable. Asparagus is a perennial. If you plant and manage properly, it will produce for 15 year or more.

How Much to Plant

To produce enough asparagus for fresh table use, plant 10 crowns for each family member. If you are especially fond of asparagus or want a surplus to can or freeze, plant at least 25 plants for each family member. If you use hybrids, reduce the number of plants by half.

Soil Prep

Any well drained soil will produce good asparagus. Use deep fertile sandy or loamy soil. If your soil is clay you should condition it with peat moss, leaf mould or straw so spears will emerge straight.

Using a raised bed is especially helpful with heavy soils. Have a soil test made at least 6 months before planting. Take soil samples at 12 inches in depth. The soil pH should be around 6.0 to 6.7. This is because asparagus grows poorly in acidic soils. Choose a site relatively fee of perennial broadleaf weeds and grass.

If possible, start building up the organic matter (humus) content of the soil at least a year in advance of planting. This can be done by turning under green manure crops, animal manure, straw, peat moss or leaf mould. Till the soil deeply several times during the year to have it in fine tilth at the time of planting. Use commercial fertilizer in addition to manures. Follow soil test suggestions. On average soils that have not been tested, broadcast 3 to 5 lbs of 5-10-10 per 100 sq. ft. of bed.

Planting

Crowns (roots) should be planted in rows 4 feet apart with the crowns spaced 12” – 18” inches apart in the row. The distance between rows can be reduced, but this may shorten the life of the bed. Closer in-row spacing will increase yield. Use large, well-rooted, one-year-old, disease free crowns, purchased from a reliable source. To grow your own crowns, drill seed in the spring ½ inch deep and 2 inches apart in rows 2 to 3 feet apart. Germination is hastened by soaking seed in water for 5 to 6 days before planting. Dig and transplant the crowns the following spring. One ounce of seed produces about 700 crowns.

In the Moncton area plant crowns after danger of hard freezes is over, usually around the end of May but before plant growth starts. 

Plant the crowns in a trench 8 inches deep. Make the trench wide enough to accommodate the root system of the crowns when fully spread out. In placing the crowns in the trench be sure to have the buds pointing upward. Cover the crowns with 2 inches of soil. As the plants grow, backfill soil around the plants gradually until the trench is filled and level with the rest of your garden. 

Annual Maintenance  

Cultivate when necessary to control grass and weeds to insure a good crop of large spears. During the harvest period, asparagus can withstand shallow cultivation.  

Each spring just before the spears start to grow, broadcast a complete fertilizer such as 5-10-10 on the bed at the rate of 2 to 5 lbs per 100 sq. ft. This should be done about May 1 for our area in Moncton. Give the bed a second application of fertilizer at the end of the cutting season. 

Allow the plants to grow until they have turned brown. Then cut down the fern and destroy it. If cut down before frost the next year’s crop of spears is reduced. 

Harvesting  

Do not harvest asparagus the first growing season after planting crowns. It can be harvested (cut) for short time (not to exceed two weeks) the second year. Weak plants and small spears result from harvesting too much, too early. After the second-year planting crowns, harvest asparagus from 6 to 8 weeks each year. Weak plants should be harvested for less time.  

Exercise care in cutting the spears to prevent damage to those spears that have not yet emerged. Cut or snap the spears at ground level. This practice eliminates the possibility of damaging other spears.  

Preparation for Consumption

Asparagus loses edible qualities rapidly after harvest. Fiber develops rapidly after harvest. To maintain asparagus quality, wash and cool asparagus soon after harvest. If the asparagus wilts, it can be made turgid by soaking in cool water. 

How to Establish Asparagus from Seed

1st Spring Plant seed for crowns
2nd Spring Dig crowns and plant in permanent site
3rd Spring Harvest lightly (2 to 3 weeks)
4th-15th Spring Harvest 6 to 8 weeks each Spring
Asparagus Schedule (from seed)

How to Establish Asparagus from Crowns

1st Spring Dig crowns and plant in permanent site
2nd Spring Harvest lightly (2 to 3 weeks)
3rd-15th Spring Harvest 6 to 8 weeks each Spring
Asparagus Schedule (from crown)

Troubleshooting Asparagus Problems

Symptoms Possible Causes Controls
Tops turn yellow or brown and die back Rust (fungal disease) Cut tops close to ground in fall
Reddish-brown, orange or black pustules on stems of leaves Rust (fungal disease) Destroy infected plants and move planting area to new location
Shoots wilt and turn yellow then brown Fusarium Wilt (fungal disease) Rotate and remove old plant debris. Plant in well drained area and use fungicides
Root rot fungal disease
Small spears immature plants Asparagus produces small spears for the first 2-3 years after planting
Poor fertility and/or drainage overharvested plants Do not harvest late into the season. Plants cannot store enough food for following season.
Crooked spears mechanical injury due to mishandling or windblown Windbreaks, be more careful weeding/harvesting 
Brown and soft spears frost Protect spears with mulch on nights when cold temperatures are expected
Leaves chewed slugs (emerge at night. May see slime on leaves, but no other evidence of insects.) Control insects with registered insecticide

Use commercial slug bait