Asparagus, prized for the delicate flavour of its young shoots, is a luxury if you have to buy it. In some respects it is even a luxury to grow at home, because it has a cropping season of only six weeks and, being a perennial, it takes up space all the year round.
However, gardeners who relish its flavour may find this acceptable.
Planning the crop
Asparagus does best in a fairly open position that is sheltered from wind. It needs a rich, well-drained soil, so the initial preparation of the bed is vital to success for years to come.
In the autumn before planting, dig a bed 4 ft (1.2 m) wide to accommodate two rows. Dig well-rotted manure or compost into the topsoil at the rate of a bucketful to the square yard. Lighten heavy soil by adding sharp, gritty sand.
If the soil tends to become sticky or waterlogged, make a raised bed enclosed by railway sleepers, stones or breeze blocks.
The following spring, rake the bed level and work in 4 oz of general fertiliser per square yard (120g per square metre).
How much to grow
Six mature plants — those more than four years old — should yield one average helping of spears a week during the six-week season.
The main distinction is between purple-tinged and white-tinged types.
`Connovers Colossal’: purple-tinged; plump shoots; very tender tips.
`Martha Washington’ and `Mary Washington’: purple-tinged; both are outstanding for size and quality.
`Purple Argenteuil’: purple-tinged; large tips of fine texture.
`White Cap’: white-tinged; ready slightly earlier than purple-tinged varieties.
How to grow asparagus
Asparagus can be grown from seed; but for quicker results, buy plants that are one or two years old. Do not try to transplant roots older than this.
One-year-old crowns are best, but they will not yield spears large enough to eat for two years.
Plant in early April in the south, and about two weeks later in the north of England and in Scotland.
Use a spade to make trenches 8 in. (200 mm) deep, 3 ft (1 m) apart, and wide enough to take the plants’ roots when spread out flat. Replace about 2 in. (50 mm) of soil to give a domed base.
Remove the plants from their packing and set them 18 in. (455 mm) apart in the trenches. Spread out their roots, and cover as quickly as possible with soil.
Cover the trenches with 3 in. (75 mm) of soil, and firm the surface. Allow the trenches to fill up gradually by drawing soil from the sides as hoeing proceeds during the summer. By October the bed should be level.
For the first two years, lightly hoe to keep down weeds. Water thoroughly in dry spells. In late October or early November, when the stems turn yellow, cut down the ferns to within 1 in. (25 mm) of the soil and mulch with well-rotted manure or compost.
Each spring, dress the rows with a general fertiliser at the rate of 2 oz per square yard (60g per square metre). Follow this routine of organic manuring in the autumn, and fertiliser application in the spring.
In the third spring after planting, decide whether to grow in ridges — a method that will produce longer, blanched spears — or on the flat, where the stems will be shorter but may be cut earlier.
To make ridges, draw up the soil to a height of 5 in. (130 mm) just before the crop is ready to be cut.
Level out the ridge in autumn.
On the flat, leave the soil as it is.
When the bed is established, cut back the foliage to 6 in. (150 mm) from the ground when it changes colour each autumn, and burn it.
Raising new plants
Asparagus can be raised from seed instead of buying plants, but it will take an extra year to produce spears for cutting.
In April, soak the seeds overnight in lukewarm water and sow in drills ½ in. (12 mm) deep and 12 in. (305 mm) apart. When the seedlings are about 6 in. (150 mm) high, thin out until they are Ii in. apart.
Water them generously during the summer and plant out in their permanent bed during the following April.
Pests and diseases
The pests most likely to occur are Asparagus beetle, cutworms, slugs and snails. The principal diseases and disorders are frost damage and Violet Root Rot.
Do not harvest shoots grown from one-year-old crowns during the first two seasons. In the third year take only one or two spears from each plant.
In subsequent years, harvest for only six weeks, allowing subsequent shoots to grow into ferns. If the plants are encouraged to grow in this way, the bed should continue to produce good crops for up to 20 years.
Harvest the ripe spears when their tips are about 4 in. (100 mm) above the soil. Use either a special asparagus cutter or a serrated knife, cutting the base of the spear up to 4 in. (100 mm) below soil level.
If not used immediately, stand the spears in iced water for a few hours, then wrap and store in the refrigerator until they are needed. In this way it is possible to cut a number of spears daily, saving them until you have enough for a meal. This is better than allowing them to become too large.