Asparagus: A Small-Scale Agriculture Alternative

Published February 1994

United States Department of Agriculture
Cooperative State Research Service
Office for Small-Scale Agriculture

Easy to plant and care for, asparagus comes back every year(with minimal labor except for harvesting. Its high value brings early income to direct marketers before harvest of other vegetables or(as a good complementary crop(strawberries.

Asparagus, native of temperate regions, succeeds best where either low temperatures or drought stops plant growth for a 'rest.' Asparagus should not be considered for commercial production where warm conditions result in the plant's growth all year.

Asparagus grows and yields best in deep, well-drained sandy loam soil. However, it tolerates heavier soils as long as the water table does not come within 4 feet of the surface. The soil should be free of perennial weeds.

Planting Techniques

Planting can be done anytime in the spring after the soil warms to 50° F. Asparagus should not be planted in cold, wet soils which can harbor Fusarium crown rot disease.

To open furrows, a lister plow or middlebuster throws soil in opposite directions. Only a 6-inch deep trench is needed, and no deeper. The deeper the plant, the lower the yield.

Rows should be at least 5 feet apart. This permits good air circulation and helps stop onset of foliar fungal diseases.

Asparagus is generally planted using 1-year-old crowns. A crown is a root system of a year-old plant grown from seed.

At planting, 200 lbs. of 0-20-0 or 0-46-0 fertilizer per acre goes in the furrow. The crowns are toss atop the fertilizer. They won't burn. If not added at first, phosphorous won't reach roots later.

Crowns go 1 to 1-1/2 feet apart in a row. This takes between 5,800 and 8,700 crowns per acre. Costs run about $130 per 1,000 crowns or from $780 to $1,170 per acre, including fertilizer and lime (if needed), soil preparation, etc., total cost should be about $1,500 acre.

Crowns placed in the trench should have the crown buds facing up with the root systems spread out as much as possible. Cover the trench with soil up to the original soil level. However, do not compact the soil over the row, or spear growth will be seriously delayed. With good soil moisture, new spears emerge in about a week.

Harvesting Techniques

Asparagus is generally harvested by snapping versus cutting. Snapping has the advantage of harvesting an "all usable" product. The spear snaps at the point where fiber starts to develop. Cutting spears below the soil with a knife adds more weight to the spear but the lower 1/3 of the spear is tough and fibrous and has to be discarded. Also, cutting below the soil injures other potential buds that will send up new spears on the crown. Snapped asparagus should command a higher price than cut asparagus.

In California and certain other States, commercial asparagus growers still cut below the soil with a knife because the fibrous butt end of the spear helps to slow water loss in the tip of the spear so it can survive several days of transit.

Asparagus spear are harvested when they reach a height of between 5 to 9 inches, with a diameter of at least 3/8-inches of larger. The first harvest year is actually the year after crown planting. Harvesting lasts 2-4 weeks, depending on how long the mature fern stays green. In subsequent years, the harvest season can be extended for 6-8 weeks.

Contact a State Extension specialist to find out how long the harvest can last. In the east, in the cool spring, asparagus grows very slowly, and a 9-inch spear can be harvested with the spear tip being tight. When temperatures rise, a 5-inch spear may have to be harvested before the tip opens up or starts to "fern out." Spears allowed to fern out must be snapped and destroyed to deny insects a site to lay eggs and to prevent the delay of new emerging spears. Stop harvesting when 3/4 of the spear's diameter reaches less than 3/8 inch.

Fiber development (toughness) of the spear is related to the tightness of the spear tip. The tighter the tip, the more tender the spear is. Spear diameter has no bearing on toughness.

Asparagus can be harvested by hand into buckets. It is tiring work. Or a person can harvest an acre of asparagus in 2 hours riding a harvest-aid(easily home-made to straddle the rows(traveling between 1/2 to 3/4 mph.

Asparagus is very perishable and must be put into an ice water bath immediately after harvest. It can then be drained and placed in plastic bags, and stored under refrigeration between 32 and 40( F for 2 weeks without an appreciable loss of quality.

However, the grower shouldn't store for more than 2 days thus giving the consumer the longest storage time possible. Wholesale growers will pack the spears into 30 lb. pyramid wood or corrugated cardboard containers.

Marketing Techniques

Many growers sell asparagus by direct marketing (roadside market, pick-your-own, or farmer's market). Many growers who have a roadside stand located on a well-traveled road do well. Others advertise through newspapers, telling the people to come to their farm to pick it themselves or to buy it already picked.

Pick-your-own marketing involves considerable consumer education on how and when to pick.

Wholesale marketing of asparagus for the small grower is not profitable due to the added production costs. Wholesale buyers usually want the asparagus packed in a certain container, or require the asparagus to be hydro-cooled, using equipment in a packing-house that showers ice cold water on top of the packed asparagus to remove the field heat. They will buy huge quantities of asparagus (tractor-trailer loads) over a certain period of time.

Also, when growers analyze the cost of the packaging, cooling, transportation, etc., the price per pound they receive is usually very low compared with the price received by those growers who retail direct to consumers.

Wholesale marketers are forced to take whatever price is offered for their product, regardless of the quality.

Another way to wholesale asparagus, besides selling to produce wholesalers, chain stores, etc., is to sell to area hospitals, nursing homes, schools, etc. A small-scale grower may be able to receive a satisfactory price, and be able to "unload" some unanticipated asparagus during heavy growth.

Another sales option is to become familiar with chefs of fine restaurants in our area. Take them some asparagus and let them try it.

Other growers practice "value added"(changing the product and selling it in a different way other than in the raw product stage. For example, getting the necessary license to preserve green or white asparagus by pickling it and packing it in glass jars enables a grower to command a premium price and will bring off-season income if sold during the winter. Mail-order can be done.

White Asparagus

White (blanched) asparagus is traditionally grown in Europe by mounding up the adjacent soil over the asparagus rows in the spring before the spears emerge to a height of 10 to 12 inches. Once the tip of the spear emerges through the mounded soil, it is cut off at the base by digging into the mound. This is very labor intensive but the product can bring a price of about $3 to $5 per pound.

An easier way to grow white asparagus is to suspend black plastic over wire hoops, bent over and spaced 5 to 6 feet apart over the row. One side of the plastic is weighted down with soil and the other is anchored by placing 2 X 4's on the edge of the plastic. When the spears emerge, the 2 X 4's are put to one side and the edge of the plastic is lifted to snap the white spear. The black plastic has to be at least 4 mils thick to block out the sunlight. Otherwise, the spears turn green.

Varieties

The old Mary and Martha Washington varieties are dioecious, meaning they produce male and female flowers on separate plants. Female plants produce seed which fall to the ground, germinate, and become an asparagus seedling weed problem. They also have to expend more energy to produce seed, so spear yield is less.

All-male hybrids have been developed by Rutgers University in New Jersey to have superior high-yielding characteristics with no seeds produced. Some of these popular all-male varieties include Jersey Giant, Jersey Knight, Jersey Prince, and Jersey King. Jersey Centennial is a variety consisting of 50 percent male and 50 percent female plants.

The all-male hybrids yield 3 to 4 times more than the older, open-pollinated varieties. Growers following good cultural practices should be able to expect the following yields:

• 500 lbs. per acre the first year after planting
• 1,000-1,500 lbs. per acre the second year
• 2,000 lbs. per acre the third year
• 3,000 lbs. per acre the fourth year
• 4,000 lbs. per acre the fifth year

Other dioecious varieties for warmer climates include hybrids developed at the University of California. These include the F1 and F2 hybrids of UC 157, Ida Lea, and Apollo. They produce a high-quality 7- to 9-inches spear when daytime temperatures are warm. Yields are still less than those of New Jersey hybrids in warm climates.

Diseases and Disorders

Spears can be damaged by frost. If a frost is predicted, go out and harvest everything above ground. Spears should be mowed off at ground level after frost, being worthless.

Fungus diseases of importance include asparagus rust, Phoma sp., and Fusarium crown and root rot. Rustwill infect asparagus by attacking the fern growth. Orange rust pustules form on the fern and cause it to die back. Phoma forms elliptical (football shaped) spots on the fern stalks and also causes fern dieback. Approved fungicides must be applied after harvest when ferns reach 4 feet tall and then reapplied every 14 days throughout the season until late fall. Fusarium attacks the roots and the crown of the plant. It is present in the soil and plants will take it up through the root system when they are under stress.

Stresses can come from improper soil Ph; low fertility; excessive harvesting; and insect, disease, and weed infestations. Failure in any of these areas can lead to asparagus decline. The soil Ph should be between 6.5 and 7.5. Add limestone if soil Ph is below 6.0.

Insects

The cutworm feeds at night below the soil on one side of the spear tip. Spears are then unmarketable. Cutworms can be controlled using an approved insecticide.

Asparagus beetles lay eggs on spears, making them unmarketable. During fern growth after harvest, they chew on stalks, stripping off the green material, causing fern dieback. Asparagus beetles are controlled with an approved insecticides.

European asparagus aphids feed on fern growth, injecting a toxin. This results in dead crowns the following spring. So far, infestations have been sporadic throughout the Midwest.

Weed Control

Weeds are controlled mostly by hand hoeing and cultivation since no preemergence herbicides are labeled for use in asparagus during the planting year. The better the weed control during the planting year, the more fern growth for the next year's crop.

The following spring, about 3 weeks before asparagus emerges, mow dead fern with a mower or bush hog. Delaying fern mowing until then will keep the soil temperature about 5 degrees colder than bare soil and discourage spears from emerging in an early warm spring.

Approved, preemergence herbicides may be applied right over the shredded fern because asparagus is a no-till crop. Cultivation will bury unwanted seeds from the female plants and run the risk of damaging crowns.

Asparagus Crown Sources

This list is intended only as a reference and does not imply endorsement; there undoubtedly are other suitable sources of crowns.

Information Source

For an illustrated publication on "Asparagus Production, Management, and Marketing," send $6 to Ohio State University, Piketon Research Extension Center, 1864 Shyville Road, Piketon, OH 45661. Telephone: 614-286-2071.

by Carl J. Cantaluppi, Research and Extension Horticulturist, The Ohio State University, Piketon Research and Extension Center; and George B. Holcomb of the Office of Communication, U.S. Department of Agriculture, for USDA's Office for Small-Scale Agriculture (OSSA); Howard W. "Bud" Kerr, Jr., Program Director, Office of Small Scale Agriculture.

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All uses of fungicides, pesticieds, and herbicides must be registered by appropriate State and/or Federal agencies before they can be recommended.

CAUTION: Fungicides, pesticides, and herbicides can be injurious to humans, domestic animals, desirable plants, and fish or other wildlife if they are not handled or applied properly. Use all products selectively and carefully. Follow recommended practices for the disposal of surplus products and their containers.

Published February 1994

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