Growing Asparagus in the Home Garden Presentation

Growing Asparagus in the Home Garden

Michelle Infante-Casella Agricultural Agent/Professor Rutgers NJAES Rutgers Cooperative Extension, Gloucester County

• Asparagus officinalis has been cultivated for thousands of years. It was first thought to be domesticated by the Macedonians about 200 B.C.

• It is native to Eurasia and it was said to grow wild in seaside dunes along the Mediterranean Sea and the British Isles. That would explain and confirm the ability of this plant to have salt tolerance.

• The crop was thought to be brought to North America by English colonists. Asparagus 1942 ~8,000 acres in NJ Increased to ~10,000 acres in the 1960’s Asparagus in the 1970’s

• In this decade acreage of this crop plummeted due to fields dying from disease. Primarily Fusarium Crown Rot – a soil borne disease that weakened crowns. • Rutgers University researchers worked to breed new varieties that were disease resistant, higher yielding and that were selected to have all male off-spring. • Severe diseases for this crop include: – Fusarium Crown Rot – Purple Spot – Asparagus Rust Asparagus Today

With about 1,000 acres planted with asparagus, New Jersey is the nation’s 4th largest producer, but still a distant 4th behind California, Washington and Michigan. Some Facts About Asparagus:

• Family: Liliaceae • Genus/Species: Asparagus officinalis • Season: Cool season Exposure: Full-sun Zone: Hardy from Zone 2 to 8 • Nutrition: Asparagus is good source of vitamin A and C and minerals and is low in calories – less than 3 calories per spear. • Dioecious, meaning that it has separate male and female plants. • Plant Part Eaten: grown for its stems or spears. • Ferns sometimes used for flower arrangements. Some More Facts About Asparagus:

• Asparagus is a hardy perennial. It is the only common vegetable that grows wild along roadsides and railroad tracks over a large part of the country. • Although establishing a good asparagus bed requires considerable work, efforts will be rewarded. • A well-planned bed can last from 20 to 30 years. • Asparagus is one of the first vegetables ready to harvest in the spring. Farm Production of Asparagus

• Most of the asparagus harvested in the United States is sold as fresh produce. The United States produces around 25,000-30,000 acres of asparagus with a value of $80-100 million. U.S. acreage is currently only about one-third of what it was 15 years ago due to competition and increased imports from Central and South America. Asparagus Yield

• For most home gardeners, a 20-foot row or 100 square feet of bed is generally adequate.

• That’s equivalent to 20 planted crowns or 10 pounds of harvested asparagus per season Male vs. Female Asparagus Plants • Asparagus plants are naturally either male or female. • The female plants bear seeds, which take considerable energy from the plant and sprout new seedlings, which cause overcrowding in the bed. • Male plants produce thicker, larger spears because they put no energy into seeds and have no weedy seedling problem. • A genetic line that produces only male plants was discovered at Rutgers University and has been incorporated into some truly amazing varieties. Female Plants Produce Seeds Varieties

• The hybrid asparagus cultivars ‘Martha Washington’, ‘UC 157’, ‘Jersey Giant’, and ‘Mary Washington’ produce better than the standard cultivars.

• Male asparagus cultivars such as Jersey types (‘Jersey Giant’, ‘Jersey Knight’, and ‘Jersey Supreme’) are more productive and resist diseases better than the female cultivars (‘Washington’ types).

• Varieties with female cultivars are less vigorous and produce many red, berrylike fruits that become volunteer weeds in the garden. Sourcing Asparagus Crowns or Seeds

• Walker Brothers Inc. - https://www.walkerplants.com/

• Johnny’s Selected Seeds – https://www.johnnyseeds.com/vegetables/

• Nourse Farms – https://www.noursefarms.com/

• Many other seed companies and garden centers Site Selection for Planting

• Because asparagus remains in the same place several years, it is important to select the right spot and prepare the seedbed well.

• Asparagus does best in full sunlight and deep, well- drained, sandy or light- textured soils.

• Asparagus plants do best on the edge of a garden, along a fence or in their own space. Soil Preparation Before Planting

• Before planting, make sure that the soil is free of trash, soil insects, and perennial weeds.

• In late fall, the year before spring planting, spread a 3”- 5” layer of organic matter such as manure, rotted leaves, or compost over the beds. Till or spade the beds to a depth of 10 to 12 inches and turn the soil to mix all the organic matter beneath the soil surface.

• Test the soil for both fertility and pH at least a month before planting. Asparagus grows well in soils with a pH of 6.5 and will grow poorly if the soil pH is below 6.0.

• Add lime if needed to raise the soil pH as per the soil test recommendations. Planting Asparagus Crowns

• Asparagus crowns can be planted as soon as soils thaw in the spring. Generally mid-March. • Place the plants in a trench at least 12-18 inches wide and 6-8 inches deep. • The crowns should be spaced 9-12 inches apart in the row. • Spread the roots out uniformly, with the crown bud side up, in an upright, centered position, slightly higher than the roots. • Cover the crown with two inches of soil. Gradually (over time) fill the remaining portion of the trench during the first summer as the plants grow taller. Maintenance of Asparagus Beds

• Asparagus roots and crowns have a tendency to "rise" as the plants mature, the crowns gradually growing closer to the soil surface.

• For this reason, many gardeners apply an additional 1 to 2 inches of soil from between the rows to “hill” the rows of asparagus. Fertilizing Asparagus

• Before planting a new asparagus bed, broadcast and hoe in or incorporate ¼ pound of nitrogen, phosphate, and potassium per 20 feet of row or as directed by a soil test report. • For established beds, scatter 2 pounds of 10-20-10 fertilizer (or its equivalent) per 20 feet of row before growth begins in the spring, late February or early March. • After the last harvest (usually in early-mid June), apply an additional 1 to 2 pounds per 20 feet of row. If available, use a nitrogen-only fertilizer like 21-0-0 at this time. Always water the fertilizer into the soil as to not burn the tips of emerging spears. Crowns vs. Transplants Laying Out Crowns

9-12” Stages of Growth: Early Spring, Late Spring and Summer

April July-August June Color Differences of Spears Harvesting Asparagus Harvesting Tools:

• Sharp Kitchen Knife • Shears • Asparagus Knife* Harvesting Duration

• Asparagus should not be harvested the first year it is planted. • It can be harvested the second year for no more than two weeks. • The plant is still expanding its root storage system and excessive removal of spears weakens the plants. • During the third year of growth and thereafter, the spears may be harvested from their first appearance in the spring for as long as 6 to 8 weeks. • Harvests generally begin in late April or early May depending on spring temperatures and should be stopped in early June. Over-cutting asparagus spears will be detrimental to the long-term future health of the crowns.

Therefore, never cut the planting for more than 8 weeks after the 3rd year of planting. • Why? – There needs to be enough spears left to grow sufficient fern to make energy (stored carbohydrates) for the crown to produce new buds over the summer growing period to make new spears next spring. How to Harvest Asparagus

• Harvest spears that are at least 6 to 8 inches in length by cutting or snapping. Cutting is the preferred method • To cut, run a knife shallowly into the soil, or just at the soil line, at the base of the spear and carefully cut it. Because the spear is cut below the point where tough fiber develops, it becomes necessary to remove the fibrous base from the tender stalk before cooking. Cutting may damage some spear tips that have not yet emerged from the ground. Be careful to just cut no further than the spear you are harvesting. • To snap, grasp the spear near the base, near the soil line, and bend it toward the ground. The spear will break at the lowest point where it is free of tough fiber. Storage of Asparagus Spears • Even after harvest, spears are still “alive” and will grow in length and respire. • Place fresh cut spears upright in a container of clean water. Water should be no more than 2” deep. • If to be eaten within a couple of days, spears can be kept at room temperature. • If storing longer, keep refrigerated. • Spears that are not kept in water will lose firmness and become limp. • Do not wet the tips of the asparagus, as they will rot and slime. Preparing Spears for Cooking

• Fresh asparagus from the store usually requires a fair amount of trimming to remove the woody section. • Snapping the spear by holding the cut end and middle of the spear generally eliminates this problem. • Asparagus spears may contain soil particles and need to be washed several times to remove dirt before cooking. This is especially true if harvested after a rain event. • Most asparagus purchased in the store has been washed during the packing process, but still needs to be washed before consuming at home. Growth Stages of Spears Fully grown, mature plants Asparagus plants in fall Primary Diseases

• Fusarium Crown Rot can be an issue in soils, especially where soils do not drain and high moisture occurs weakening the crowns. Plant resistant varieties.

• Asparagus rust can be a problem in NJ. Moisture left on the plant (ferns) for 10 hours can help to spread the disease. If needing to water with overhead sprinklers, water in the morning so ferns can quickly dry during the day. Plant resistant varieties. Primary Insect Pests of Asparagus

• Asparagus beetles • Asparagus aphids • Cutworms • Japanese beetles

• Monitoring for insects will help you determine when and if you should use pesticides. • Many insects and their egg masses can be removed by hand. Insect Pests

• Asparagus beetles are commonlyCommon found in home Pest Problems plantings. If numerous, they may be controlled by a suggested insecticide or by handpicking.

• Asparagus beetle adults feed on young shoots during the harvest season, chew holes in the shoots, and lay small, dark brown eggs standing on end on the spears. Insect Pests

• Asparagus aphid (Brachycorynella asparagi). • The aphid was first reported in southern and central Minnesota in 1982. The asparagus aphid is a minute, blue-green sucking insect that usually feeds on asparagus fern. • In the process of feeding, it injects a toxin into the asparagus plant that is translocated down the stem into the dormant buds. The toxin causes the buds to elongate into new shoots prematurely, producing a "witch's broom," or a dwarfed, very bushy, short plant with silver, blue- green color. Asparagus Aphid Life Cycle

• The asparagus aphid lays its eggs in late summer or early fall. The eggs over-winter on the fern and fall to the ground by spring. Unharvested asparagus, which ferns out in early spring, is highly susceptible to early aphid infestations because egg masses are allowed to hatch and the aphid's life cycle begins. • The aphid feeds only on the fern, not on asparagus spears. Removing asparagus fern in late fall after it has dried down greatly reduces potential aphid infestations the next year. Cutworms in Asparagus

• Cutworms can cut off asparagus spears below ground and even cause damage by feeding on the tips of spears above ground. Shoots damaged by cutworm feeding develop into crooked spears and must be picked and culled. Common Problems

• Crooked spears – from mechanical injury – from wind damage – from insect feeding • Spears with white tips – from freezing or over fertilization (salt injury) • Loose tips – from hot temperatures (growth accelerated) What causes spears to bend or deform?

Spears with mechanical injury from stones in soil, insect feeding or cuts from knives will become bent or contorted with severe bends and may also develop loops as the side of the spear that was undamaged continues to develop.

Winds can cause one side of the spear to dry out quicker than the other causing the spear to bend and point in the direction of the prevailing wind. White Tips

• From freezing or over fertilization (salt injury) Lose Tips

• From high temperatures when emerging Asparagus Spear Quality

• Pencil thin or thick stems can be equally delicious. Contrary to popular belief, thinner stems are not an indication of tenderness. Thick stems are already thick when they poke their heads out of the soil and thin stems do not get thicker with age. Tenderness is related to maturity and freshness. Watering Asparagus

• Asparagus plants need deep watering to reach “feeder” roots that forage deep into soil. • Water the beds thoroughly, and allow the top 1 inch of soil to dry before watering again. • The time periods in between watering varies, depending on soil type, soil moisture loss from wind and temperature and size of plant growth. • In some soils, asparagus roots can reach 4-6 feet deep if adequate soil moisture is available. • Do not overwater, since high soil moisture will promote soil-borne diseases like Fusarium to flourish. • The use of a soaker or drip hose is best to keep moisture off asparagus ferns and reduce the incidence of foliar diseases. Managing Asparagus After Harvest

• Be sure to keep asparagus beds adequately watered. • Check for diseases and insect pests; if in high numbers treat to prevent excessive fern damage and disruption of photosynthesis. • In fall, allow ferns to completely dry down before removal. If completely dry, ferns will easily break off at ground level. Ferns should be removed and composted or discarded away from the planted area if infected with foliar diseases or if insect infestations were a problem. • Carbohydrates from the fern will translocate down into the crown during fall, “feeding” the crown to provide energy for spring growth. Thank you for your attention during this presentation.

Michelle Infante-Casella Agricultural Agent/Professor