Asparagus Growing Guide

An attractive and delicious perennial vegetable, asparagus can thrive for years. Its lacy green foliage grows 6–8 feet high, and can be used as an ornamental summer screen. It may grow for up to 20 years or more in the same spot, given the proper care.

A tasty addition to meals, soups, and salads, this easy-to-cook vegetable is low in calories and high in vitamin A, riboflavin, and thiamin.

Those who want to grow from crowns (roots) can try our best-tasting Purple Passion and our extremely high-yielding Jersey Knight variety. We also offer seeds for Mary Washington, the most popular variety in the U.S.


For Planting Crowns

When to Sow Sun/Part Shade Crown Spacing Row Spacing Planting Depth Days to Maturity
When daytime temperature exceeds 75-85° Full Sun 12-14 inches 4½ feet 6-8 inches in trench One year after planting


For Planting Seedlings

When to Sow Sun/Part Shade Seed Spacing Row Spacing Spacing after Thinning Days to Maturity
In late winter greenhouse or after the final spring frost Full Sun 3-5 inches 2 feet Remove female plants for highest yield One year after planting

Soil and Fertilizing
It's best to have your soil tested before planting, to find out what nutrients and pH levels are needed for your plants. For a thorough soil test, visit an Agricultural Experiment Station in your area (scientific research center) or consult your local county extension agent (also known as a Land Grant University).

Asparagus prefers a deep, well-drained sandy soil with a pH level between 6 and 7, but can do just fine in other soils as long as they're well-drained. Too much rain or poorly drained soil will threaten the health of the plants.

Planting and Watering Crowns
Asparagus prefers sunny days, and needs a long growing season to do best, with ideal daily temperatures of 75-85 degrees and nightly temperatures of 60-70 degrees.

Choose healthy crowns with firm, fleshy roots. Avoid shriveled or papery roots, because they're unlikely to produce.

It is best to fertilize based on soil test results. But if you lack those results, spread nitrogen at 75 pounds an acre; phosphorous at a rate 250 pounds per acre; and potassium at 300 pounds per acre. Scale down this amount based on the size of your asparagus patch.

Create a V-shaped trench 6-8 inches deep for your crowns, and apply super triple superphosphate (0-46-0) in the trench at 200 pounds per acre in addition to the other phosphorous you've applied. Plant your crowns 12-14 inches apart for thicker spears; 8-10 inches is sufficient for thinner spears. Don't worry about the direction the buds are facing. Cover your crowns with 1-2 inches of soil to protect them from the sun.

As the asparagus begins to grow, fill the trench gradually with more soil, being careful not to cover the foliage. It should reach ground level by the end of the growing season. Side dress a 5-10-10 fertilizer in late July or early August, at the rate indicated by your soil test.

Asparagus needs a decent application of water to produce well during the first year of growth. Irrigate weekly, wetting the soil to eight inches below the surface. After the first year, cut back to 2-3 inches of water, applied slowly, every two weeks when the weather is dry enough to require it.

Planting and Watering Seedlings
Soak asparagus seeds for two days at a temperature of 85-90 degrees (use a heating mat) and start growing them in seedling pots 12-14 weeks before field planting time. (Plant only when danger of frost has passed). Use a sterile growing medium containing vermiculite and peat moss, planting seeds ¾ of an inch deep in two inch diameter pots, or seed 2 inches by 2 inches in flats. Germinate the seeds at 75-80 degrees.

Apply a soluble, complete fertilizer, such as 15-15-15, at half the recommended rate 4, 8 and 12 weeks after sowing the seeds. Rinse the foliage lightly with water after fertilizing to avoid injury to the tender growth. Excessive fertilization promotes large, over-tender tops and small root systems with limited reserves in the storage roots.

Asparagus needs a decent application of water to produce well during the first year of growth. Irrigate weekly, wetting the soil to eight inches below the surface. After the first year, cut back to 2-3 inches of water, applied slowly, every two weeks when the weather is dry enough to require it.

To further maximize your yield, weed out the female flowers. Otherwise, the female plants will go to seed rather than focusing on growing spears. Check the seedlings closely when the flowers start to appear. You'll need a magnifier for this, because they're very small. Female flowers have three-lobed pistils; male flowers are larger and longer.

Late Season Soil Replenishment
In fall of the first year, towards end of the growing season, clear browned/dead ferns away. The following spring, broadcast lime as needed, and add fertilizer and herbicide as indicated from a soil test.

Each succeeding fall continue to remove brush. And in spring, before the asparagus emerges, broadcast lime if your soil test indicates to do so, spread half the recommended fertilizer, apply the herbicide, and irrigate in one inch of water.

Harvesting / Storage
Wait until the year after planting to harvest your asparagus. You can do so in one of two ways: snapping or cutting the spears, once they are between 7-10 inches in length. Use a specially designed asparagus knife if you cut, taking the spears at a point an inch below the soil line. Avoid cutting too deep, or you may damage the crown. You can protect against this by building a 4-inch ridge of soil around the spears as they start to appear.

If you prefer to snap, bend the spear until it breaks, leaving a stub at the surface. One reason to cut rather than to snap is that diseases may attack the exposed stub.

Asparagus is best eaten fresh. However, it will store for up to two weeks in the refrigerator. Trim an inch off the ends, and put bundles in glass containers where they can stand up in an inch of water. Cover the top part loosely in plastic and refrigerate. Change the water when it gets cloudy.

You can also freeze asparagus by chopping it into one-inch pieces, blanching and then plunging it into an ice bath. Next, separate and spread the individual pieces on a cookie sheet. When frozen, you can then place them in a container for freezing up to a year. The frozen pieces can be cooked without thawing in soups and other dishes.

**************************************************************************************************

For soil testing or other questions specific to your growing climate, please contact your local county extension agent. Visit http://www.almanac.com/content/cooperative-extension-services to find the office nearest you.

Click Here to Download this Growing Guide