Asparagus

Establish your own asparagus bed in late winter to early spring, with a little patience, you will be able to harvest succulent spears for the next 20 years. Linda Ross shares her growing tips for this perennial spring harvest favourite.

Asparagus has been cultivated for 2000 years, and celebrated for its delicious taste, succulent texture and suggestive shape. Early spring spears dipped in a homemade hollandaise sauce are a highly anticipated treat. Asparagus crowns outsell lots of other more obvious vegetables during winter. Could it be because of that distinctive flavour? Or perhaps gardeners know that asparagus is a good source of folic acid and that it is high in potassium? Or is it the spears’ mythical aphrodisiac qualities that have people coming back for more? If you’ve been one who has purchased an asparagus crown over the last few months here is how to maximise your harvest.

Asparagus is a perennial plant native to central and southern Europe, northern Africa and western and central Asia. It is a member of the lily family, which includes plants such as onion, garlic, leeks, turnips, lilies and gladioli. The ancient Greeks loved wild asparagus but it was the Romans who first cultivated it. The Emperor Augustus coined the phrase ‘velocius quam asparagi conquantur’, meaning to do something faster than you can cook asparagus. Julius Caesar first ate it in Lombardy and wanted it served with melted butter. And in the time of King Louis XIV asparagus was dubbed ‘The King of Vegetables’.

Position

Wild asparagus grows in dry meadows, sand dunes, limestone cliffs and volcanic hillsides. So it stands to reason that it is sure to grow in your backyard with few problems. Find a spot with good drainage in an open sheltered position. But don’t think you can just squeeze one in – you will need a bed dedicated to growing asparagus!

Soil

Asparagus is a perennial vegetable arising from a root system of fleshy rhizomes known as the “crown”, with long feeder roots that can grow to a depth of 1.5-2 metres. Since asparagus is a deep-rooted crop, soils need to be well drained. Alluvial loams, peaty soils and sandy loams are the most suitable. Improvement of the soil with a load of well-rotted manure is essential, as asparagus is productive for up to 20 years. Two weeks before planting crowns dig in a complete fertiliser.

Growing guide

Asparagus can be grown from seed or crowns. Planting crowns is easier and more productive. There are male and female plants; the male plants are more productive so it is advisable to remove the female plants, which can be identified by their red fruits. Plant one or two-year-old crowns during winter or early spring into garden beds in a single row with the crowns planted 40cm apart. Dig a trench 30cm wide x 20cm deep. In the bottom make a 10cm mound and place the crowns on top, spreading the roots either side, then cover with 5cm of soil. As the stems grow gradually cover them with soil. By autumn the trench will be filled with soil. Pull out weeds as they grow rather than using any herbicide. Water during dry weather.

During April and May, the asparagus fern dies down as the plant undergoes a natural dormancy period over winter. The debris from the fern is usually cut and mulched back into the soil, with care taken not to damage the crown.

Harvesting

The trick to growing asparagus is patience. Don’t be tempted to harvest spears until the third year after planting. Wait until the spears are 10 – 15 cm long and cut on an angle under the surface of the soil with a sharp knife. Leave one spear uncut to grow into a fern, this will help restore the plant’s energy and prolong next season’s harvest. The harvest lasts for six weeks the first year and eight weeks the next year. Do not harvest after midsummer or you will get thin spears the next year.

Pests and Disease

There are a number of common asparagus diseases, such as fusarium crown rot and wilt, asparagus stem-blight, asparagus rust (only in Queensland), anthracnose and phytophthora blight. Orientation of rows with the prevailing wind will allow free flow of air through the asparagus plot to help in lowering disease incidence. Thrips can cause distortion to spears and can be controlled by companion planting basil and spraying with Natrasoap.

Tips and tricks

* White asparagus spears are produced by being grown in the dark. When asparagus spears are exposed to sunlight, they turn pink before greening up.

* Fresh purple asparagus has  a 20% higher sugar content than green asparagus.

* When the season begins spears may only need to be cut every third or fourth day, but as the season progresses and temperatures rise, spears must be harvested daily. At the height of the season single spears of asparagus can grow more than 2 cm an hour!

* Like cut flowers, freshly harvested asparagus needs to be kept in cool, humid conditions. Some people stand the fresh spears upright in a container with 1cm of water and store it in the refrigerator. Others wrap the spears in a paper towel, or a clean damp tea towel, then store in a plastic bag in the crisper section of their refrigerator for up to 5 days.