When you receive your asparagus crowns they should be planted as soon as possible providing the soil and weather conditions are favourable. If planting has to be delayed transfer the crowns to a box or seed tray and cover the roots with moist compost to prevent them drying out. Keep them in a cool light place.
Asparagus prefer a deep, well-drained and reasonably fertile soil that is slightly alkaline. Choose an open sunny position, sheltered from late frosts and cold winds. The area to be planted must be free of perennial weeds.
The site should be well worked to a spades depth, forking the soil layer below, incorporating plenty of well-rotted garden compost or manure. Ideally the soil should be left to settle for a week or two.
The crowns can be planted in single rows 40-45cm (15-18") apart with 1.2m (4ft) between rows. For each row take out a trench 30cm (12") wide and 20cm (8") deep. Replace some soil to form a curved ridge at the bottom of the trench approximately 10cm (4") high. Place the crowns on top of the ridge, carefully spreading out the roots. Cover them with about 5cm (2") of soil and lightly firm, taking care not to damage the roots. The crowns should be covered quickly to prevent them drying out. The remaining soil is replaced gradually during the season as the shoots develop.
The crowns can be planted in a multiple row system 2, 3 or 4 rows may be planted in a bed, spacing the crowns 30cm (12") apart in each direction in the same manner as described above. If more than one bed is to be planted allow a pathway of 90cm (3ft) between each. The close planting in this method achieves higher yields from a given area but the spears produced will be thinner.
After planting apply a general fertilizer and ensure the plants do not go short of water in the weeks after planting, and water as necessary during dry spells.
In the year after planting spears can be cut from mid April through to mid May. Harvest the spears when they are 12-18cm (5-7") above the ground, cutting the stem 12.5cm (1") below the soil surface. In subsequent years cutting can continue until the 12th June, after which allow the foliage to develop. This will enable the crowns to build up resources for the following year.
In the autumn, cut down the yellow foliage to within 2.5cm (1") of the ground. A 5-8cm (2-3") layer of garden compost or well-rotted manure can then be applied. In spring apply a general fertilizer. Keep the beds weed free by hand weeding.