Asparagus in not a vegetable crop for the inpatient gardener, to get any thing near a decent crop it takes 2yrs of growing.
Preparation is everything with this veg as a good asparagus bed can last for decades and the plant really dislikes disturbance once it gets going.
Good drainage is needed so consider a raised bed system if needs be. A good light position and sheltered from strong winds as the plants ferny foliage is quite tall (4ft). Dig in a good quantity of rotted manure or compost in autumn before planting in the following spring.
Remove all perennial weed roots when preparing the soil, as its almost impossible to do so once the asparagus roots have established with out disturbing them.
A week or so before planting cultivate the soil, incorporating a good hand full of general fertilizer per sq yard.
Plants are usually supplied as 1yr old crowns, plant these 2½ft apart in trenches 6 inch deep, wide enough to accommodate the long thick succulent roots that should be spread out evenly, rows should be about 3ft apart.
Back fill the trench half way up, and continue to do so through the summer as the plant grows.
Keep the bed weed free by hand weeding and well watered in dry weather. By early November the foliage will die back and can be cut down to 2 inch above soil level.
At the same time top dress the row with a good general fertilizer and mulch the bed with a thick layer of rotted manure/compost to encourage a good supply of shoots next year.
In the second year after planting the emerging spears can be cut when they are about 4-6 inch high. Cut them below the soil surface, down to 2 or 3 inch using a long narrow knife or a special asparagus knife, which has a serrated edge. Take great care not to damage the crowns.
Cropping should stop around the end of June, to allow the remaining shoots to fully grow and build up strength in the crowns for the following year.