Asparagus
Vegetable Farming in South Africa

Asparagus is a perennial plant or herb from the family Asparagaceae. The plant grows from a rhizome underground, commonly referred to as the crown.

©Louise Brodie

Scientific name: Asparagus officinalis
Common Name: Asparagus

Plant Description

Numerous shoots sprout from the crown and emerge above the ground and this is the part that is harvested and eaten.

The shoots or asparagus spears are harvested when they are immature and are still tender and crisp, once they have grown to between 15 and 20 cm above the ground. If spears are allowed to grow out beyond this point they harden and produce strong stems and branches and have fern like leaves.

The asparagus plant can grow to over two meters tall. From the branches small red berries will form and these develop into the seeds used for propagation. When the plant goes dormant in late autumn or early winter, the branches can be cut back and collected for the seeds attached to them.

Uses

Asparagus is eaten as a vegetable boiled, steamed, fried or raw in salads. It is rich in vitamins A, B6, C, E and K also contains high levels of folate, calcium, iron and protein. Is said to help prevent kidney stones. Asparagus is also blanched and sold in cans.

Soil Requirements and Preparation

Prior to planting do a representative soil sampling and analysis of the field that is to be planted. Asparagus can remain productive, on the same patch of land, for 15 years. For this reason, soil preparation is very important. Asparagus does best on sandy and sandy loam soils. It can be planted on soils with a pH of between six and seven.

A month before planting soil should be ripped to a depth of at least 600 mm to loosen the soil. If soils are too acid and the pH must be adjusted, then lime should be added to bring the pH to above six. The soils are now deep ploughed and turned to between 400 mm and 500 mm.

Your preplant organic fertilizer can now be worked into the soil as well as the lime. A month later when you are ready to plant, apply your preplant chemical fertilizer and mix this into the top 20 cm of soil with a disc plough. This also cleans and levels your planting area and gets rid of any weeds that have taken hold. You are now ready to draw your planting furrows and start planting your asparagus crowns.

Climate

Asparagus can be planted in a wide climate range. It does best when the temperatures during the production or harvesting period range between 15°C and 26°C. Higher temperatures result in more fibre in the spears, making them less appetizing and therefore less saleable. Temperatures below 12°C result in slower growth and therefore lower yields.

Cultivars

Mary Washington, California 500, Connover's Colossal and many hybrids that have been bred for unique attributes; like longer and tighter more slender spears and have a resistance to certain diseases. Some hybrid varieties are UC66, UC72 and UC157. In choosing a variety or more than one it is advisable to speak to your extension officer or seed company in your region for advice.By Louise Brodie