How to grow and harvest asparagus

Posted in All Gardening Advice, Vegetables and Fruit, March, on

Special Growing Requirements

Prepare the bed by digging in well-rotted manure and removing perennial weeds. Asparagus likes the soil freely drained, so add grit if gardening on heavy clay. It’s also important to keep the bed free of weeds. They compete with the crowns, so mulch deeply with grit or compost in early Spring.
Give a high-nitrogen feed in early summer to encourage the ferns. Cut them to the ground in late autumn when the ferns are brown.
Watch out for asparagus beetle, a small yellow and black beetle with a red head. They and their buff-coloured grubs eat the forms, sometimes defoliating them completely and so weakening them. Pick these pests off whenever you see them.
Final Planting/Thinning Distance
Plant crowns 30cm (12in) apart in March or April. Leave 1m (3ft) between the rows. Dig a wide trench about 20cm (8in) deep and 30cm (12in) wide. Form a ridge of soil down the centre of the trench, about 10cm (4in) high. Place the crown on the ridge, draping the roots either side of the ridge. Cover with about 5cm (2in) of soil, then add more soil as the stems grow, aiming to completely fill the trench by autumn. Keep well watered.
As a rough guide, ten established plants should yield about 3kg (7lb) of spears, over a six-week period each year for up to twenty years.  I have thirty crowns, which produce enough for regular meals for our family of two adults and two children.  
Do not harvest spears in the first year after planting, and only a few in the following year.  After that, you should be able to cut lots of spears.  
When the crowns stop producing heavily, they are coming to the end of their natural season.  Stop harvesting then and allow the ferns to grow.