Succeeding in growing asparagus

Which variety to choose?

The colour of asparagus varies depending on the amount of light received: to obtain white asparagus, they are deprived of sunlight by earthing up. The lack of light prevents them from performing photosynthesis, which makes them white. Growing green and purple asparagus does not require earthing up. The choice of variety is made according to the intended growing method. Among the best varieties, we recommend, for example, asparagus ‘Lima’, which is an early variety offering good yields, asparagus ‘Argenteuil’, particularly suited for producing white asparagus, or asparagus ‘Rosalie’, which produces purple spears.

Where to plant asparagus?

Asparagus thrives in all climates. It enjoys rich, light, and well-drained soil. It prefers rather sandy soils that warm up quickly in spring. Asparagus appreciates sunny exposures, although it can also be planted in partial shade. It is a perennial vegetable that will produce for many years (> 10 years), but its cultivation requires a lot of space.

When and how to plant asparagus?

Planting takes place in March-April (from February in mild climates) on a plot that has been prepared and amended the previous autumn. Asparagus should be planted as soon as it is received, as it must not dry out.

• In autumn, dig trenches about 40 cm wide and 25 cm deep (15 cm for green and purple asparagus), spaced 1.5 m apart.
• Loosen the bottom of each trench using a spade or fork.
• Mix well-decomposed compost or manure into the soil, and possibly a little coarse sand to improve drainage.
• In March-April, form small mounds of soil in each trench, about 10 cm high and wide, spaced 50 to 60 cm apart.
• Place the crowns, with the tip facing upwards, on the mounds.
• Backfill the trench to cover the asparagus with about 3 cm of soil.
• All that’s left to do is water.

How to care for them?

The first harvest occurs after three years of cultivation during which the asparagus intended for white harvesting will be earthed up as they grow. All asparagus requires regular but moderate watering.

First year of cultivation:

Asparagus, regardless of their colour, is covered with a layer of soil 3 cm deep. They will settle in and develop their roots. Maintenance involves regular weeding or mulching to limit the appearance of adventive plants.

Second year of cultivation:

The crowns are covered with:

• 7 or 8 centimetres (12 cm in light soil) of soil for green and purple asparagus,
• about twenty centimetres of soil for white asparagus,

Then, tie the shoots to stakes or to supporting wire, placed during planting, as they grow.

Third year (and subsequent years):

The third year of cultivation corresponds to the first harvest, which takes place from April.

White asparagus must be earthed up from March: this involves gradually forming mounds of soil, 30 to 40 cm high, around the shoots. These mounds will be removed in autumn.

For all asparagus, apply compost at a rate of 1 kg per m².

Any earthing up / de-earthing and the application of compost should be repeated each year throughout the cultivation.

What are the pests and diseases of asparagus?

Asparagus are not fragile; however, during their cultivation, you may encounter:

• The asparagus beetle. This is a beetle that weakens the plants by devouring the foliage. The control method involves manually collecting the insects and spraying a solution based on pyrethrum (Tansy).
• The asparagus fly. Its larvae burrow into the stems, causing deformities and inhibiting the growth of the spears. It is advisable to burn the dried foliage at the end of the season.

The most common disease is purple rhizoctonia: this is a disease caused by a fungus that persists in the soil. It affects the base of the stems and the roots, which then become covered with a purple felt. Symptoms include yellowing and drying of the stems. To prevent it, avoid planting asparagus in a contaminated plot and grow leeks in the year preceding the establishment of the asparagus bed.

→ Find our tutorial on how to make a solution based on pyrethrum (tansy).

When and how to harvest asparagus?

Harvesting takes place from April and involves picking the asparagus as soon as it emerges from the ground. This is done using a gouge that allows you to cut each shoot at its base without needing to disturb the mound. In the first few years, harvest sparingly, over a period of two to four weeks, then allow the asparagus to grow and stake them as they develop.