Asparagus can be started from seed, or you can buy roots (also called crowns). A plant started from seed will be ready to start harvesting the third spring. A plant started from roots will be ready to begin harvesting in season.
Plant purchased roots into a well-prepared area. Work plenty of compost into the bed, then dig a trench or hole about 45cm (18inches) deel Lay the roots 45-60cm (18-24 inches) apart from each other or other plants. Cover the roots with 5-10 cm (2-4 inches) of soil and, as they sprout up, gradually cover them with more soil until the trench or hole is filled.
Water and mulch well.
Plant seeds indoors in flats or peat pots about 6-8 weeks before you will be planting them into the garden. Use larger pots if the seedlings get too big before the scheduled planting then you can move them outside for planting. The first year you should plant the seedlings at the solid level they are at in their pots. Keep them well watered and mulch them with compost. The second summer, they can be planted as for roots, described above.