Asparagus
This delicious vegetable is expensive to buy but easy to grow. The shoots are cut below soil level when they are about 10cm (4in) long, but all cutting must cease soon after the middle of June to allow the plants to develop over the summer and build up the crowns for the following spring. Asparagus plants must not be cropped until they are at least three years old and then only moderately until they are well established.
An asparagus bed will last for a good many years, so it should be dug to a depth of 60cm (2ft), incorporating manure in the second spit, and if the soil is heavy add more cinders or other material that will break up the soil and improve the drainage as the crowns are liable to rot in heavy, wet soils. It is advisable on heavy, ill-drained soils, to raise the level of the beds about 16cm (6in) to improve the drainage. The beds are usually made about 1.3m (4ft) wide with an alley of 60cm (2ft) or so between them.
Crowns are planted in spring or seed may be sown. If planting crowns make sure the roots are spread out well and then cover them with 7cm (3in) of soil. They should be spaced about 30cm (1 ft) apart, in rows 40cm (15in) apart.
Seeds may be sown either directly into the permanent beds or in a seed bed or frame and then thinned out eventually leaving the plants 23cm (9in) apart. They will be ready for planting into their permanent bed the following spring. Female plants, which are berry-bearing, do not produce such good crops as the male plants and should be discarded, replacing them with male plants. It is not possible to distinguish between them until the plants are two years old so the rogueing must be done when the plants are in their permanent beds, or the seedlings can be kept in the seed bed and planted out as soon as they can be sorted out.
Topdress the beds in the spring with a thick layer of well-rotted manure and keep them weeded but do not use a hoe as the roots are so near the surface. The top growth must be cut down in the autumn when it turns yellow.
Wendy Whiteman
Planted asparagus by seed two summers ago, cut them back last year, but was considering covering all my raised beds with black plastic this year. Is it ok to cover the bed with the asparagus in it? or what is recommended for asparagus?