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Plant Manual for Jersey Knight Giant Asparagus

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Plant Description

Huge crops! This productive variety will give you impressive yields each and every year. Its extra large, uniform, tender spears are good for fresh eating, cooking or making salads. Cold-hardy and heat-tolerant. Harvest from early April through mid May. Self-pollinating. Pkg. of 10.


The best way to succeed is to plan before you plant. So you’re interested in growing vegetables and/or root crops; do you know where you want to plant which varieties? Learn all you can about each plant’s needs, taking into consideration the following:

  • Sun and good soil
  • Space for future planting

Sun and Good Soil

An area with good sunlight, usually between 6-8 hours a day, is recommended for vegetables and root crops. Some leafy vegetables like lettuce will do well in shadier areas. Check out the specific requirements for the varieties you want to grow. Well-drained and fertile soil are also necessary components for a good planting location. If your soil needs amending, take this task head on before you decide to plant.

Space for Future Plantings

When marking out your garden bed, be sure to consider the probability that after a few crops of your own homegrown edibles, you’ll want to plant more. Especially if you have an excellent growing location at your fingertips, it’s better to start with a smaller area and leave room for expansion. You’ll thank yourself later!


Few things are as delicious as homegrown asparagus, and the success of your harvest begins right with the planting site and method. For maximum growth and yields later on, give your plants the best foundation possible.

Before Planting

Before you plant, check your soil pH. Contact your local County Extension Office for information about soil testing in your area, or purchase one of our digital meters for quick and accurate results. Ideally, your asparagus needs a soil pH between 6.5-7.0.

Planting Site

  • Asparagus needs plenty of room to grow.
  • Pick a sunny location to plant.
  • Space plants 12-18 inches apart with rows spaced 5 feet apart. Wide spacing promotes rapid drying of foliage to help prevent the onset of fungal diseases.
  • Dig a hole 6 inches deep, or dig a furrow (trench) 6 inches deep and wide enough to accommodate the outspread roots. The trench can be as long as you want.
  • In the bottom of the hole or furrow: make a mound about 2 inch high of dehydrated cow manure (or compost mixed with the soil taken from the hole).
  • Position the plant with the bud facing upward, on top of the mound, so the crown (center of the plant) is 3 inches below the soil surface.
  • Cover the hole or furrow with soil and gently firm the soil to remove any air pockets. Do not compact the soil over the newly filled hole/furrow or the emergence of the asparagus will be severely reduced.
  • Water your new plants thoroughly.
  • No pruning is necessary at planting time.

Other Considerations

  • Weeds can be a major problem for asparagus. On small acreage, light cultivation with a hoe may be used to remove weeds— but avoid a rototillar or any other tillage implement that can damage the crown. These could reduce yields and promote diseases.
  • Organic mulches such as grass clippings, wood chips, straw/hay can be applied 4-5 inches thick to suppress weeds.

Soil Preparation

Preparing your soil before you plant will greatly improve your plant’s performance and promote healthy, vigorous growth. It is a good idea to have your soil tested to determine if it is lacking in any essential minerals and nutrients. This can be done through your County Extension Office or with one of our digital meters.

The goal of soil preparation is to replenish vital minerals and nutrients, as well as break up and loosen any compacted soil.

When To Prepare Your Soil

Soil preparation can be done at any time that the ground is not too wet or frozen. Your plants may be planted even when temperatures are quite cool. If a hard frost is expected, it is advisable to delay planting for a while until temperatures become more moderate. Generally, as long as your soil is workable, it is fine to plant.

How To Prepare Your Soil

  • Roots grow faster when they’re spread out. Dig the hole deep and wide enough so the root system has plenty of room to easily expand. Keep the topsoil in a separate pile so you can put it in the bottom of the hole, where it’ll do the most good.
  • To loosen the soil, mix dehydrated cow manure, garden compost or peat moss (up to 1/3 concentration) into your pile of topsoil. Make sure the peat moss you get is either baled sphagnum or granular peat. You can also add our Coco-Fiber Potting Medium or 2 or more inches of organic material and work in evenly with the existing soil.

Your lawn can provide you with ideal organic materials such as grass clippings and shredded leaves. Not only will the grass and leaves break down to provide soil nutrients, but they will help loosen the soil as well. You can gather these in the fall with spring planting in mind.

Common soil amendments:

  • compost
  • sand
  • manure
  • lime
  • peat moss

Adding organic materials, such as our Coco-Fiber Potting Medium and compost will improve most every soil type. Organic materials bind sandy soil particles so they retain moisture and nutrients better. They also break apart clay and silt particles, so that water can infiltrate and roots can spread.

Soil Types

  • Clay and silt soils are made of very small particles. They feel slick and sticky when wet. Clay and silt hold moisture well, but resist water infiltration, especially when they are dry. Often puddles form on clay or silt soils, and they easily become compacted.
  • Loam soil is a mix of sand, silt or clay, and organic matter. Loam soils are loose and look rich. When squeezed in your fist, moist loam will form a ball, which crumbles when poked with a finger. Loam soils normally absorb water and store moisture well. Loam soils can be sandy or clay based, and will vary in moisture absorption and retention accordingly.
  • Sandy soils contain large particles that are visible to the unaided eye, and are usually light in color. Sand feels coarse when wet or dry, and will not form a ball when squeezed in your fist. Sandy soils stay loose and allow moisture to penetrate easily, but do not retain it for long-term use.


Fertilizing is an excellent way to replenish the natural nutrients in your plant’s soil. For asparagus, have your soil tested to determine phosphorus and potassium needs. Asparagus usually likes a balanced fertilizer of 5-10-10 or 8-24-24.

The first 3 years in spring, apply a well-balanced fertilizer. Starting the fourth year, delay application until June or July (immediately after harvest). This approach encourages vigorous growth of the “fern,” which produces and stores nutrients in the roots for next year’s production season.

Insects and Diseases

Every plant has the future potential for disease and insect damage. Factors such as location and weather will play a part in which issues your plants encounters. If available, disease-resistant varieties are the best option for easy care; and for all types of plants, proper maintenance (such as watering, pruning, spraying, weeding, and cleanup) can help keep most insects and diseases at bay.

Crown & Spear Rot

Appear as soft water-soaked lesions on shoots and at soil line, or slightly above or below. Lesions elongate rapidly and become light brown. As lesion collapses and shrivels affected side of spear becomes flattened and shoot becomes extremely curved and may collapse. Infected crowns have yellow-orange colored tissue. Caused by over harvesting, growing in acidic soil and water logged soils. This is a soil borne fungus.

Natural Control

  • Serenade® Garden Disease Control

Fusarium Wilt

Infected mature plants decline in productivity and growth. During summer months stunted, light yellow ferns characterize infected plants. Reddish-brown discoloration at base of infected stalks, and may extend into crown. Feeder roots may rot off completely, or may show reddish-brown color. Fungus lives in the soil.

Natural Control

  • Minimize stress to plant
  • Don’t harvest when production declines to 70% of season’s highest yield. Jersey Knight shows some resistance.

Other Control Options

  • Consult County Extension Agent

Purple Spot

Appear as elliptical, slightly sunken lesions .03 - .06” across and 0.125” long. Reddish-purple later develops a tan-brown center, especially if the lesion is large. Usually appear on lower half of new spears and are very superficial. Internal tissue of spear is not affected. Purple Spot is worse following cool, wet weather when spears are emerging. Subsides in dry weather.

Natural Control

  • Last years fern growth should be removed or incorporated into the soil.

Other Control Options

  • Consult County Extension Agent


Infection begins in spring and produces orange stage of disease and is occasionally found on new spears as yellow or pale orange pustules in concentric ring pattern. Spores are airborne to new fern growth where brick red pustules are formed on all parts of the fern. Ferns may turn yellow or brown, defoliate and die back. In fall the spores turn black and will over winter. Rust causes reduced plant vigor and reduced yields.

Natural Control

  • Provide proper irrigation.
  • At end of fern season, cut and burn.
  • Serenade® Garden Disease Control

Asparagus Virus I & II

When plant is infected with either but only one of the virus plant vigor may be only slightly reduced. When both are present in same plant, survival and vigor severely reduced especially in young plants and aphids transmit both. Virus II can also be transmitted by pollen and is more prevalent in older cultivars.


  • Consult County Extension Agent


Larvae appear as smooth skinned caterpillars to the naked eye. Frequently roll into a C-shape when disturbed. Variegated is yellow to brown, little over an inch long with 4-6 yellow or pink diamond-shaped spots down its back. Dark sided cutworm somewhat larger, gray to greenish gray with irregular longitudinal stripes. Larvae feed at night on tender tips of new spears, eating out small areas and one-sided feeding may cause spears to curl. Variegate also feeds underground and at soil surface. Ferns seldom damaged.

Natural Control

  • Good weed control and clean up of crop residues.

Chemical Control

  • Bonide® Borer-Miner Killer
  • Bonide® Total Pest Control
  • GardenTech® Sevin® Concentrate Bug Killer
  • Bayer Advanced™ Complete Insect Killer

European Asparagus Aphid

Small blue to gray-green aphid often covered with a powdery wax. Hard to spot until damage has occurred. Damage is primarily from toxin that is injected into plant during feeding. Causes shortened internodes on subsequent growth resulting in tufted appearance. Heavy populations also leave large amounts of honeydew leading to ant activity. Shortens life of plant and cause delay in bud break in spring followed by profusion of small spears produced simultaneously.

Natural Control

  • Bonide® All Seasons® Horticultural & Dormant Spray Oil
  • Remove and burn old ferns at end of season.

Garden Symphylan

Slender, white arthropod, closely related to an insect, about 1/3” long, fast moving, lives in soil with high organic matter. Cause damage by eating small round holes in roots, crowns and below ground portion of spears.


  • Consult County Extension Agent


Small slender sucking insects and adults have 2 pair of wings. Thrips remove moisture from crop fern causing twisting of the fern branch lets as well as some twisting of the stalks. Results in loss of vigor and even death of the tops of small seedlings.

Natural Control

  • Bonide® All Seasons® Horticultural & Dormant Spray Oil

Chemical Control

  • GardenTech® Sevin® Concentrate Bug Killer
  • Bayer Advanced™ Complete Insect Killer

Asparagus Beetle

Beetle is about 1/4” long, metallic blue-black with red and white markings. Spotted beetle is bright reddish-orange with small black dots. Adult over-winters in trash around garden. When spears emerge, adults feed on spears and deposit brown-black ugly eggs on the spears that are impossible to wash off. Then dark gray larvae and adults feed on shoots and ferns causing partial defoliation and scarring. Spotted beetle larvae feed on seeds of asparagus berries and cause minimal damage.

Natural Control

  • Bonide® All Seasons® Horticultural & Dormant Spray Oil (beetle larvae)
  • Bonide® Captain Jack’s™ Deadbug Brew
  • Pick off adults before they lay eggs or destroy eggs before they hatch.

Chemical Control

  • Bonide® Borer-Miner Killer
  • Bonide® Total Pest Control
  • GardenTech® Sevin® Concentrate Bug Killer
  • Bayer Advanced™ Complete Insect Killer

Tarnished Plant Bug

Yellow-brown winged insect may have black spot or red stripes. Injects toxins into buds and shoots, causing dwarfed shoots. Treat ferns or bush growth after spear harvest when insects are present.

Chemical Control

  • Bonide® Borer-Miner Killer
  • Bonide® Total Pest Control

Japanese Beetle

Adult is metallic green beetle. Feeds on ferns. Treat ferns or bush growth after spear harvest when insects are present.

Natural Control

  • Traps
  • Bonide® All Seasons® Horticultural & Dormant Spray Oil (beetle larvae)

Chemical Control

  • Bonide® Borer-Miner Killer
  • Bonide® Total Pest Control (adult Japanese beetle)
  • GardenTech® Sevin® Concentrate Bug Killer
  • Bayer Advanced™ Complete Insect Killer


Pinpoint size, many different colors. Found on undersides of leaves. Sap feeding causes bronzing of leaves. Severe infestations have some silken webbing.

Natural Control

  • Bonide® All Seasons® Horticultural & Dormant Spray Oil

White Fly

Adults are tiny, white winged insects found mainly on the underside of leaves. Nymph emerge as white, flat, oval shapes. Larvae are the size of a pinhead. Suck plant juices from leaves causing leaves to turn yellow, appear to dry or fall off plants.

Natural Control

  • Traps
  • Bonide® All Seasons® Horticultural & Dormant Spray Oil

Lygus Bugs

Small oval insects, color range from pale green to reddish brown or black. Feed by sucking sap, signs of infection discoloration, deformed shoot and stems, curling of leaves and lesions.

Chemical Control

  • Bonide® Borer-Miner Killer
  • Bonide® Total Pest Control
  • GardenTech® Sevin® Concentrate Bug Killer
  • Bayer Advanced™ Complete Insect Killer


Pruning is an important part of proper edible plant care, and in the case of asparagus, it’s particularly easy to do. Asparagus foliage that forms after harvest is strengthening the crown and root system for next year’s crop, so you’ll want to prune in late fall or early winter.

Pruning Tips

  • Wait until all the foliage has died back and turned brown or yellow. This normally happens after the first frost.
  • Cut the plants back to the soil surface and apply mulch to help against deep freeze or changes in soil temperatures. (Mulching also helps with weed control.)
  • If you have issues with disease or insects, it’s best to cut the tops off of your asparagus. You should not need to remove the entire fern.
  • Before the new spears appear in spring, remove the old tops.


Spraying is important to the survival of your plants. To handle potential diseases and pests, reference the guidelines below to know what you should spray, and when you should use it.

Before you begin, read and follow all instructions on labels.

When To Spray


  • Bonide® Borer-Miner Killer for asparagus beetles and cutworms.
  • Bonide® Total Pest Control for cutworm and asparagus beetle.


  • Bonide® Borer-Miner Killer for larval stages of asparagus beetle, tarnished plant bug, lygus bugs and adult Japanese beetle.
  • Bonide® Captain Jack’s™ Deadbug Brew for asparagus beetles.
  • Bonide® Total Pest Control for larval stages of asparagus beetle, tarnished plant bug, lygus bugs and adult Japanese beetle.

Dormant thru Harvest

  • Serenade® Garden Disease Control for crown rot, rust and more.

At the First Sign of:

  • Bonide® All Seasons® Horticultural & Dormant Spray Oil for aphids, mites, beetle larvae, thrips, whitefly and more.
  • GardenTech® Sevin® Concentrate Bug Killer for asparagus beetle, cutworms, thrips, Japanese beetle, lygus bugs and more.
  • Bayer Advanced™ Complete Insect Killer for asparagus beetle, cutworms, thrips, Japanese beetle, lygus bugs and more.


General Guidelines

  • During the first 2 years after planting, asparagus plants need 1 to 2 inches per week. If you are not receiving adequate rainfall you will need to water. Use drip irrigation if possible.
  • Mulch around the plant with compost or grass clippings to help soil moisture and reduce weed growth.
  • After year 4 you can reduce irrigation to every 2-3 weeks.


Are you ready to enjoy delicious homegrown vegetables? Harvest is the time to enjoy the results of your hard work. Keep a few things in consideration as you reap the benefits of your labor: the best time to harvest your plants, and how to store your vegetables.

When to Harvest

Asparagus spears should be lightly harvested the first two years until the plants are established. By the third year, you should have a nice crop from late April until spears grow thin, usually late June.

A common mistake made by new growers is to harvest too long. This can cause a permanent reduction in vigor and health of the plant and reduce yields the following years. It is best to harvest in the morning when air temperatures are cool.

To harvest spears, cut just below the soil surface or snap off just above the ground by bending it from the top toward the ground. Harvest spears 5 to 9 inches in length.

Annual Average Yield per Year:

  • One plant, 8 to 10 spears
  • A family of 4 plants, 20-30 crowns.


After harvest immerse the spears in ice water, drain, pat dry, place in bags and immediately refrigerate. Asparagus will keep in the refrigerator for up to a week. To freeze first blanch for two minutes in boiling water. Dry on paper towels and place in freezer bags.

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Trees that are shipped without soil to ensure good contact with soil in your yard. When shipped, they are about 3-4' tall with 3/8" or larger trunk diameter. When they mature, they will be one of three sizes*:


Matures to be about 8-10' tall and wide. Provides an abundance of full-size fruit.


Matures to be about 12-15' tall and wide. Gives maximum fruit yield per square foot.


Matures to be about 15-25' tall and 20' wide. A multi-purpose fruit and shade tree.

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Top-grade, bare-root trees that give you a head start on growing. When shipped, they are about 4-5' tall with 5/8" or larger trunk diameter.

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