Guest Blog: Growing your own Asparagus

This month we have the the definitive blog on Growing Asparagus.

Asparagus is a high-yielding, early-season vegetable for home gardeners. It is grown as a perennial vegetable in the UK and can yield for 12 or more years. The asparagus plant is composed of ferns, crown and a root system. The crown is a collection of rhizomes and lateral roots that initiate new ferns. Spears, which are the harvested portion of the asparagus plant, are immature ferns. Thus, if the spear is not harvested, it develops into a large fern, which manufactures and stores energy in the crown for next year’s crop.

Asparagus is a dioecious plant, which means that there are separate male and female plants. Male asparagus plants produce more spears than female plants do. Female asparagus plants produce numerous bright, red, berrylike fruits with seeds that can become volunteer weeds in the garden or field.

Preparing the asparagus bed is important as Asparagus is a perennial vegetable, attention should be given to choosing the best planting site possible. Like most vegetables, asparagus will not tolerate wet, soggy soil. Choose a well-drained field, or use raised beds to promote drainage. Asparagus will perform best on sandy, light-textured soils.

Asparagus crowns should be planted in the spring as early as the soil in the garden can be worked. Late March or early April is a good time in most areas.

Separate crowns by size and plant similar-sized crowns together; this encourages uniform growth. If crowns cannot be planted immediately, store them in a refrigerator.

Make a 6-inch-deep furrow using a garden hoe. Well rotted manure can be spread in the furrow. This is covered with an inch of soil, and the crowns are spaced 12 to 18 inches apart in the furrow. If a variety produces large-diameter spears, you should reduce spacing within the row to decrease spear

Each row should be no less than 3 feet apart so the ferns can close the canopy and shade weeds out during the summer.

If rows are spaced too close together, spear size may be reduced.

Cover the crowns with about 2 inches of soil, and as the ferns emerge and grow, gradually fill in the furrow through the summer.

Plants that are stressed by drought can become weak and susceptible to insect, disease and weed pressure.

Growers should be prepared to irrigate new asparagus plantings for the first two or three seasons after establishment. Drought stress after harvest can reduce yields for the following season.

Weed control is the most challenging aspect for successful asparagus production.  Organic mulches such as grass clippings, straw or compost can be applied 4 to 6 inches thick to suppress weeds.

Several herbicides are labelled for weed control in asparagus. Glyphosate (Round-up) can be used as a broadcast application to control winter annual and biennial weeds early in the spring before the spears emerge and after the last harvest.

Cover crops such as rye or wheat may be spring sown inter-row to suppress weeds.

Selecting a site with good drainage and optimal pH will prevent many asparagus diseases. Crown rot, a potentially devastating disease, is caused by over harvesting, growing in acidic and waterlogged soils, and excessive pest pressure.

The yield of asparagus spears in the spring is directly related to the previous year’s fern growth. Asparagus can be harvested for a limited time (two weeks) the second year after planting crowns (three years from seed transplants). Over harvesting one year can weaken the plant and decrease yields the following year. Three years after planting the crowns, asparagus can be harvested for five to eight weeks. Each year, during the first several years of production, yields will increase if the planting is managed properly. Average yields 2.5kg per 100 square feet.

Asparagus spears are best harvested by cutting them off with a knife near ground level. Most people prefer to snap the asparagus spears when they reach 7 to 9 inches in length in cool weather (less than 70 degrees F), and the spear tip is tight or 5 to 7 inches in warmer weather (more than 70 degrees). Cutting will break the spear cleanly at a tender.

To preserve freshness, harvest during the morning or evening. Expect to harvest every one to three days as temperatures increase. Spring freezes will not harm the crowns or subsequent harvests but can damage emerging spears. Thus, emerged spears may be harvested before a predicted freeze.

Asparagus has a short shelf life and may be immersed in cold water after harvest and immediately refrigerated (36 degrees F) to maintain quality.

After harvest, the asparagus planting should be fertilized with composted manure to stimulate summer and autumn fern growth. Herbicides can be applied after harvest to control any weed growth. Frost will desiccate the ferns, and they can then be cut in late autumn or early winter. Do not mow ferns in early autumn while they are still green because this will reduce the following spring harvest. We mulch the crowns to protect them from low-temperature injury. The mulch can be raked to the row middles the following spring (early April), and spears will emerge for another harvest season.

One of nature’s Superfoods

Asparagus contains high levels of vitamin A, folic acid and dietary fibre, all believed to play an important role in the fight against cancer. Vitamin A (an antioxidant vitamin) may help prevent cancer by protecting body cells from damage caused by free radicals.

Asparagus is rich in soluble fibre, known to have a protective effect against degenerative heart diseases. Asparagus also contains high levels of potassium, which may help to control blood pressure and the high folic acid content helps to reduce blood homocysteine levels, thought to reduce the risk of heart disease. Asparagus is also low in fat and sodium, making it the perfect choice for those concerned about a healthy heart.

Asparagus is one of the richest sources of ‘rutin’ (a natural substance found in plants) which together with vitamin C, can help to energize and protect the body from infections. Asparagus is also a source of iron, which boosts the immune system.

Asparagus is low in calories with less than 4 kcal per average spear, which as part of a balanced diet can help weight loss. Asparagus is also very low in cholesterol, has no fat and very little sodium so can help to maintain heart function and blood pressure levels.

Asparagus is a mild diuretic and is believed to help detoxify the body, helping it to get rid of excess water and combat cystitis.

To buy your asparagus crowns from Reads click here.