Asparagus requires a sandy loam as this soil warms up quickly in the spring because of its low moisture content. This will stimulate the plant into growth, so that the asparagus sticks can be cut early. It requires some protection against cold northeast winds; erecting some type of barrier either permanent or otherwise will protect the plants and give them shelter.
Prepare the ground by digging to a spade’s depth in the autumn and adding well-rotted compost and manure at the rate of a large bucketful to the sq. yd leave the soil rough over winter. In late March begin by forking over the soil 3 or 4 in. (76mm-101mm) deep. Apply fish manure with a 6 percent potash fertilizer at 4 oz. (120g) to the sq. yd. This dressing is appropriate each spring until the asparagus bed is exhausted, which could be up to 20 years or more.
Top dress each October with well-rotted compost and manure.
The intended asparagus bed must be completely free of weeds.
Asparagus roots are thick and succulent but dry out quickly. Therefore, when you buy your plants soak them in water for a day and then put them out into the garden covered in damp sacks, taking great care not to expose the roots to the air more than is necessary. You can buy asparagus crowns (root clumps), which are one, two or three years old; naturally, the one-year-old crowns are cheapest.
Planting should take place during late March-early April, just as soon as the soil is dry and friable; never plant when it is wet and the soil sticky. Cut out trenches 6 in. (15cm) deep and 6 in. wide, 3 ft. (90cm) apart. Remove the plants from their damp sacks and plant them 2-½ ft. (75cm) apart, as quickly as possible so that they do not dry. Place them into the bottom of the trenches, spreading the roots out carefully so that they radiate evenly all around the crowns. Cover them with 3 in. (76mm) of good soil, firming this with the back of your spade. The trench should be filled up gradually during the summer as the plant grows; by October the ground should be level.
The roots need to become established in the first year, during the second year let the fern grow well so that good crowns are built up for these will produce good shoots early the following season.
Keep down the weeds, this is extremely important for the asparagus does not itself produce any weed-smothering foliage. By November, the fern will have died back, they should not be cut back until then, as the plants need their ferny leaves with which to store up energy for the following year. Any foliage that remains at this time can be then trimmed to tidy the bed, leaving an inch or so above ground level. Top dressings of fertilizers and manures can be given each year at this time.
Allow the plant to establish and gain in size before the spears are harvested. Wait until the plants are in their third year before taking the spears; then they can be cut when they are about 4-6 in. (101mm-152mm) high. Cut them below the soil surface, down to 2 or 3 in. (50mm-76mm) using a long narrow knife or a special asparagus knife, which has a serrated edge. Take great care not to damage the crown.
Spears can be cut every two days in the early part of the season, around May time. The season is relatively short, cutting should stop at the end of June, and the remaining shoot should then be allowed to go on to produce asparagus fern. The fern itself should be cut down to within 6 inches (15cm) of the soil level just before the berries ripen; this will then prevent the ripened fruits from falling to the ground, scattering useless seeds because the aim it to cultivate only the chosen “pedigree” crowns.