Organic Gardening:

How to grow organic Asparagus

An asparagus bed can bring you luxury for 20 years

Asparagus Asparagus officinalis Family: Liliaceae (Group 6)

Asparagus is a perennial plant which can be productive for 8-20 years. Although cutting cannot begin until the second year, and full production not till the third year, a crop of such longevity (and luxury) will repay great care in preparing the growing site.

Cultivation instructions for the plant known as Lincolnshire asparagus can be found in the herbs section. Asparagus kale is a variety of rape kale. Please see the page on kale. Asparagus peas are another crop which some gardeners enjoy. Brief directions for cultivation of this crop can be found in the vegetable cultivation table.

Site/soil

Asparagus thrives on a wide range of soil types, from heavy clay to sand, provided the soil is well drained. Preferred pH is 6.3-7.5, but it does not need to be particularly fertile. Lime acid soil and avoid exposed sites, frost pockets and sites where asparagus has been grown before.

Cultivation

Traditionally grown on ridged or raised beds to give a long blanched stem. It is possible to plant on the flat, then to raise the bed by earthing up in the second season.

Prepare the ground by digging thoroughly and incorporating a good dressing of well rotted farmyard manure or compost. On heavy land do this the previous autumn. Make sure all traces of perennial weeds have been removed, as it is very difficult to weed asparagus once it is established.

Plant one-year-old crowns 10cm (4") deep, spacing them 30-45cm (12-18") apart, and with 30cm (12") between rows, in March or early April. Take out a trench 30cm (12") wide by 20cm (8") deep, making a mound in the bottom about 10cm (4") high. Handling crowns very carefully, spread out the roots over the mound and cover with about 5cm (2") of fine soil. Fill in the trench gradually as the shoots grow.

Plant module-grown asparagus in or before June, 10cm (4") deep, at the same spacing. The same method is used for seed raised indoors.

To grow from seed, either sow in modules in February at 55-60ªF (11-16ªC) for planting out the same year as above, or outside in a seedbed in spring, in drills at least 2.5cm (1") deep. Thin to 7½cm (3") and plant out the largest crowns the following spring.

During the growing season, keep the beds weed free, taking care not to damage the roots. Remove any seedlings which appear. If necessary, supply canes and twine for support to prevent the ferns blowing over. After the fern has turned yellow, cut it down to within 2.5cm (1") of ground level and draw 5-8cm (2-3") of soil over the stumps (on heavy soils do this in spring). Top dress in spring with general fertiliser.

Harvest

Older cultivars cannot be harvested until 2 years after planting, more modern cultivars may be lightly harvested in the second season.

Cutting normally starts in the second half of April. Cut with a sharp knife or an asparagus knife, which has a forked blade so a single spear can be cut without damaging the others. Cut 5-8cm (2-3") below the soil when spears are 12-15cm (5-7") tall.

If harvesting in the second season, cut for four weeks, six weeks in the third season and eight weeks thereafter.

After cutting has finished for the year, apply a foliar feed of seaweed feed. Remove any berries that appear.

Pests, diseases and disorders

Asparagus beetle: grey-green grubs, black and yellow adults 1cm (¼") long. Remove all that are seen, dust with derris. Grow chives as repellent plants.

Violet root rot: Remove and burn affected plants. Remove all residual crop plants at the end of the season and suppress rampant weed growth, on which the disease might persist. Maintain high soil fertility with balanced fertiliser application and prevent waterlogging. Following severe attacks, avoid root crops for 4 years.

Slugs can be very damaging to young plants, traps may be helpful.

Fusarium root rot causes plants to die back with decay at the base or on the roots. Remove and destroy affected plants, improve drainage and adjust pH to near-neutral. Avoid growing legumes (peas and beans) on the site for at least 5 years.

Rust is rare, but serious when it occurs and should be dealt with immediately. Cut down and burn the ferns, dust bed with sulphur at monthly intervals, preferably in hot weather, making the first application about 3 weeks after the last shoots have been cut.

Frost may kill young shoots if severe in late spring. Destroy affected shoots. Cover bed with sacking if a late frost is expected.

Unsupported plants on an exposed site may suffer from wind rock, causing rotting. Provide support.