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Asparagus, Jersey Knight

Short Description

Highly productive plants adapt and grow in any garden soil.

Full Description

A prodigious producer, this hardy variety offers up a bounty of large, tender, especially delicious spears. It is remarkably disease-resistant and thrives in pretty much any soil type, even heavy clays. U.S. Plant Patent #06,624.
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Item#: 69990
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Asparagus, Jersey Knight
Asparagus, Jersey Knight, , large
Item #: 69990
1 Offer (25 Roots)
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Product properties

Days To Maturity The average number of days from when the plant is actively growing in the garden to the expected time of harvest.

730 days

Fruit Size The average size of the fruit produced by this product.

8 inches

Sun The amount of sunlight this product needs daily in order to perform well in the garden. Full sun means 6 hours of direct sun per day; partial sun means 2-4 hours of direct sun per day; shade means little or no direct sun.

Full Sun, Part Sun

Spread The width of the plant at maturity.

15-18 inches

Height The typical height of this product at maturity.

48-60 inches

Sow Method This refers to whether the seed should be sown early indoors and the seedlings transplanted outside later, or if the seed should be sown directly in the garden at the recommended planting time.

Direct Sow

Shipping Information


Item 69990 cannot ship to: AA, AE, AK, AP, AS, CN, FM, GU, HI, MH, MP, PR, PW, VI
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Introduction to Raised Bed Gardening
If you’ve ever wanted to know just what raised bed gardening is then this is the place to start.
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How To Direct Sow Seeds
Learn how to direct sow seeds from Burpee's expert horticulturist.
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How to Sow and Plant

Asparagus may be grown from seed sown early indoors and transplanted outside after frost, from seed sown directly in the garden, from transplanted seedlings in fall or from year-old bare roots in spring.

Sowing Seed Indoors:

  • Start asparagus seeds indoors 8-12 weeks before outdoor planting date in spring in peat pots, plastic pots or trays. At least 2 x 2 inch cells works best.
  • Sow seeds ½ inch deep in seed-starting formula.
  • Keep soil moist at 70-75 degrees F
  • Seedlings will emerge in 10-14 days
  • As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow. Incandescent bulbs do not work because they get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
  • Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
  • Seedlings should be 6-10 inches tall with 4-6 stems with several buds coming from the crown when they are ready to transplant outside.
  • Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens cell structure and reduces transplant shock and sun burn.
  • When selecting a site, keep in mind that asparagus is a perennial vegetable and the planting bed should not be disturbed. Early soil preparation is essential in order to establish a healthy asparagus bed. Asparagus prefers full sun and a good organic well drained soil.
  • Space transplants 12 inches apart in a single or double row. Double rows should be 12-14 inches apart. Transplant before temperatures are 90 degrees F.

Sowing Directly in the Garden:

  • Direct sow seeds in spring when the soil is at least 60 degrees F.
  • When selecting a site, keep in mind that asparagus is a perennial vegetable and the planting bed should not be disturbed. Early soil preparation is essential in order to establish a healthy asparagus bed. Asparagus prefers full sun and a good organic well drained soil.
  • Prepare the soil by removing weeds and working organic matter into the top 6-8 inches of soil; then level and smooth.
  • Sow seeds evenly and thinly 2 inches apart, ¾ -1 inch deep
  • Firm soil lightly with your hand, water and keep evenly moist.
  • Seedlings will emerge in 10-14 days at 75 degrees F, a little longer if the soil is cooler.
  • Thin seedlings to about 12 inches apart when seedlings have at least two sets of leaves.

Planting Bare Roots in the Garden:

  • When selecting a site, keep in mind that asparagus is a perennial vegetable and the planting bed should not be disturbed. Early soil preparation is essential in order to establish a healthy asparagus bed. Asparagus prefers full sun and a good organic well drained soil.
  • Dig trenches 6-8 inches deep and 12-15 inches wide. Space rows 2 ½ - 4 feet apart.
  • Set roots in the bottom of the trench, spacing crowns (centers) 18 inches apart in the row. Spread roots out as far as possible for best root establishment.
  • Cover roots with 2 inches of fine soil and water well.
  • Plants may take 6-8 weeks to emerge.
  • Continue adding soil as the tops grow up, about every three weeks, until the trench is full, which should be about midsummer when planted in early spring.

Planting Seedling Plants in the Garden:

  • When selecting a site, keep in mind that asparagus is a perennial vegetable and the planting bed should not be disturbed. Early soil preparation is essential in order to establish a healthy asparagus bed. Asparagus prefers full sun and a good organic well drained soil.
  • Dig a hole for each plant large enough to amply accommodate the root ball.
  • Set plants in the bottom, spacing centers 18 inches apart in the row. Space rows 2 ½ - 4 feet apart.
  • Place the top of the root ball approximately ½ inch below the level of the surrounding soil.
  • Fill with soil to the top of the root ball.
  • Press soil down firmly and water.

How to Grow

  • Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, control them by either cultivating often or use a mulch to prevent their seeds from germinating.
  • Mulches also help retain soil moisture and maintain even soil temperatures. Put down a layer of newspaper 5-10 sheets thick between the rows (soak the papers in water first, so they won't blow away) and then cover the newspaper with dry grass clippings, aged bark mulch, weed-free straw, etc.  Always keep mulches off of plants’ stems to prevent possible rot.
  • Keep plants well-watered during the growing season, especially during dry spells. Plants need about 1 inch of rain per week during the growing season. It's best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
  • Do NOT cut plants back after harvest, allow them to fern and grow as long as they can before frost. They will become quite large. They need the green foliage to make food for themselves to make strong plants next year.
  • Have your soil tested for fertilizer recommendations. Fertilize after harvest and in late summer.
  • Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
  • In late fall cut tops to ground level when they have turned brown. In cooler climates mulch the ground with evergreen branches or straw after the ground freezes for extra protection. Remove this winter mulch in early spring.

Harvest and Preserving Tips

  • Do NOT harvest asparagus the first year. Allow the plants to grow and make food to store in the roots for stronger plants the following year. When plants are two years old you can harvest them for a short period. In the third year you can harvest for four weeks.
  • Harvest when new spears emerge in spring. Harvest when spears are about ½ inch wide. On average spears should be 6-8 inches tall.
  • Using a sharp, clean knife, cut young spears at ground level and set in water with the cut side down until you are ready to store the spears. Some gardeners prefer to snap the stems, but this can cause damaged tissue which can result in disease issues.
  • Harvest frequently before spears start to leaf out.
  • Do not harvest spears less than ¼ inch in diameter.
  • Prepare as soon as possible as fresh asparagus is best.
  • Asparagus also freezes well for later use. Sort the spears by thickness and “blanch” smaller ones 1 ½ minutes, medium for 2 minutes and thickest for 3 minutes. To do this, drop the spears into boiling water for the recommended time, then plunge into cold water to stop the cooking, drain and store in freezer bags or vacuum bags.
Days To Maturity
730 days
Fruit Size
8 inches
Full Sun, Part Sun
15-18 inches
48-60 inches
Sow Method
Direct Sow
Planting Time
Sow Time
2-4 weeks BLF
18 inches
Life Cycle
Asparagus, Jersey Knight is rated 5.0 out of 5 by 6.
Rated 5 out of 5 by from Growing great in clay soil I planted Jersey Knight from Burpee and a competing vendor. The Burpee have big, fat, hearty spears popping up stronger and more plentifully. I'm in zone 9A with a 2 foot tall box that's about 2/3 native clay amended with peat moss, humus/compost, and perlite. The crowns were in great shape when they arrived, even though it was hot and took me a couple days to plant them. They are tolerating the mediocre soil well and loving our recent heavy rains.
Date published: 2016-06-25
Rated 5 out of 5 by from Growing like a forrest All the roots looked healthy upon arrival. I planted them in well prepared soil in a raised bed and they shot up within two weeks and as of July 6 have sent up more shoots. It looks like next year we'll have plenty to eat!
Date published: 2013-07-06
Rated 5 out of 5 by from Awesome Asparagus! I bought this variety and Purple Passion for raised beds. This was my first try at asparagus and they have been growing beautifully! I am very happy I selected Burpee's asparagus. Other venders roots/plants that I looked into (and bought!) were not even close to this quality. I would highly suggest this product.
Date published: 2013-06-29
Rated 5 out of 5 by from Best root system I have ever seen Asparagus is coming up and I planted them less than 2 weeks ago. The root system on these is unbelievable, very long and healthy.
Date published: 2013-05-05
Rated 5 out of 5 by from Great Asparagus We planted the Jersey Knight about 4 weeks ago (just after Feb 14th) and ALL the roots have shoots already! They are anywhere from 4 to 1 shoot per root and they are anywhere from a few centimeters to a foot and a half high! We are very excited.
Date published: 2013-04-08
Rated 5 out of 5 by from Beautiful roots I wish I had purchased these roots first. Over the years I have replanted many roots that didn't grow. This year I started a new row and bought from Burpee. The roots are beautiful. Big and healthy with big crowns ready to grow. All my roots have sprouted their first little spears. I paid less than I would have locally and have a superior product.
Date published: 2012-06-03
  • 2016-08-28T06:20CST
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