Asparagus is seen as a luxury vegetable, with tender spears shooting through the soil in spring and early summer. The nutritious spears are delicious fried with garlic or as an ingredient in soup. Unusually for a vegetable, asparagus is a perennial plant, that once established can provide a harvest for 15 years or more. Asparagus is planted as 1 year old crowns, spaced 30 centimetres apart and 45 centimetres between rows. Crowns thrive in nutritious, but light, sandy soils. In heavy soils, asparagus is better grown in raised beds or large containers. All male varieties are preferred as they devote all their energy to growing spears rather than producing seed.
Asparagus varieties differ in harvest time, with some varieties ready for picking in early April, and others available in June and early July. There are also differences in colour, from the widely seen green spears, to the less common purple varieties. For the longest harvest period, selecting a range of asparagus types is required, as the cropping period for a single type is relatively short at 4 to 8 weeks. After this point, any further asparagus spears should be allowed to mature, to give the plants energy for the following year's harvest.
On an allotment, my experience is that asparagus is not the easiest crop to grow. The crowns need two years to become established, with only light picking recommended in this period. During this time, an asparagus bed needs to be kept weed free, a task done by hand to avoid disturbing the roots below the surface. Once a bed is mature, weeding remains as the biggest challenge. Asparagus plants grow tall but provide little leaf cover to the soil, giving the opportunity for weeds to germinate at their base. There is no shortage of wild seed flying across an allotment, and the result is that a gardener needs to be constantly clearing away weeds when young, to avoid disturbing the soil and risk damaging the roots of the asparagus crowns.