6 Simple Steps For Growing (& Harvesting) Asparagus

Learn how to grow asparagus in your garden and you'll enjoy a vegetable that is low in calories and sodium. Additionally, asparagus retains its flavor when frozen.

Asparagus is a perennial that can produce for twenty seasons or more if the soil is well cultivated. If you are thinking about growing asparagus, be prepared; asparagus will only be ready for harvest in the third year after planting. 

How Much Asparagus to Plant

This really depends on how much asparagus you would like to eat. The common guideline is 10-15 plants per person. If you enjoy eating asparagus multiple times per week, and would like to freeze some of your harvest, you should plant as much asaparagus as you have room for. From experience, most people growing asparagus never say they have too much.

How to Grow Asparagus from Root

The best option for growing asparagus is to purchase roots (often called crowns) from a nursery or farm. [If you are thinking of planting asparagus from seed, you will have to wait an additional year of growth before your first harvest.] 

Growing from a root will supply you with edible spears in the third year. Ensure that you find asparagus roots that look and feel firm/fresh.

Spacing and Soil

When thinking about how to grow asparagus, spacing is important. For example, if you want to grow six plants you will need a row that is about 12.5 feet long. If you want to plant additional rows of asparagus, ensure that the rows are spaced 4 feet apart. Asparagus has a deep root system, and will shade other plants.

Growing asparagus in raised beds is often ideal because of the deep root systems they produce. Growing asparagus requires soil that is well drained and fertile. The soil should be slightly acidic but not below a pH of 6. Additionally, when you are thinking about how to grow asparagus, note that it should be planted in the full sun or in light shade.

When and How to Plant Asparagus - Trenching

Asparagus planting can begin as soon as the ground can be worked, which usually means that the soil temperature should be around 5°C or 40°F. Asparagus planting can be started any time in between the last frosts of early spring.

Here are the guidelines for how to plant asparagus:

  1. Dig a trench 18" wide and 10" deep for growing asparagus

  2. Mix a liberal amount of compost or fertilizer that is high in nitrogen, potassium and phosphorous, into the soil removed from the trench. We suggest asking local gardeners for their recommendations regarding the quantity of fertilizer/compost to use for your soil.

  3. Fill the trench back in with the mixture of compost and soil until the trench is now only 6 inches deep.

  4. Tamp it down, and place the roots in the soil, crown side up, ~2 feet apart from each other.

  5. Cover with 2-3 inches of the remaining dugout soil/compost mixture. This covering will protect the roots from subsequent frosts.

  6. As the plants sprout, continue to fill in the trench until it is full. It should take most of the first growing season to fill the trench. Filling gradually aids in keeping down weeds(because the soil is continually disturbed).

The First Two Years

When considering how to grow asparagus from root, it is important to know that asparagus will only fully produce in the third year. You can harvest shoots in the second growing season that are at least 7 inches high. You should not pick beyond one month, however, but wait for the fuller harvest in the third year. It is important to let the majority of the spears grow, and allow the plant to fern(grow feathery tops).

The ferns aid in photosynthesis and will strengthen the entire plant by transferring carbohydrates and energy to the roots. You should also continue to fertilize once in the Spring and Fall.
Each Fall, when the leaves have been killed off by frost, the stalks should be cut down to ground level.

Watering Asapargus

A general guideline is to water your asparagus once a week. Asparagus does not need a lot of water. If you experience rain at all during the week, you do not need to water.

Weeding Asparagus

Weed around the plants, but be careful to avoid damaging the roots. Hoe the weeds out with shallow strokes. You should be careful not to till deeper than 3 inches. Many people also cover the ground with a heavy layer of mulch, or hay, to keep the weeds at bay. This layer of mulch will also keep moisture in the ground for the benefit of the asparagus plants, and will give you the best chance of growing asaragus successfully.

Harvesting Asparagus

Now that you've learned how to plant asparagus, it is time to reap the rewards of harvesting asparagus. The asparagus season usually lasts for 6-8 weeks. During this time, the spears can be snapped off at ground level, leaving the whiter part of the stalk in the ground.

The stalks you pick should have at least 5-8 inches high, and have tight buds(tops). If the buds are have begun to open, the spears are past their prime. Stop harvesting asparagus when the the new stalks start growing thinner, and leave these stalks to grow to fern.

A Summer Crop

Traditionally, growing asparagus will produce a crop for harvest only in spring, but it's possible to have a summer crop if you have plants to spare. Choose a number of asparagus plants you are willing to let grow and don't harvest from them, but continue to let them grow until mid-summer(July). Then cut back the whole plant, and it will begin to produce spears. Harvest these as suggested in the above "harvesting asparagus" section.

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