How to grow Asparagus

How to grow Asparagus - Description

  • Asparagus is a perennial and will produce for many years when properly planted and maintained.

  • It has underground storage roots and compact stems called rhizomes.

  • The roots store food and the rhizomes produce edible shoots or asparagus spears.

  • If the spears are not harvested, they rapidly develop into fern-like bushes 4 or more feet tall.

  • The foliage produces carbohydrates, which is again stored in the roots.

  • Asparagus has both male and female plants. Both sexes flower and the female plants produce small, round, red berries in the autumn.

  • Female plants do not live as long or produce as well as male plants.

How to grow Asparagus - Crop Rotation

  • Asparagus will need a permanent bed outside the rotation system.

  • The soil in the chosen bed should not have grown asparagus in the previous three years.

How to grow Asparagus - Site and Soil

  • Asparagus plants can remain productive for up to 20 years, so it's worthwhile spending time on preparing the bed to give them a flying start in life.

  • For a decent crop, asparagus needs to be given lots of space and is ideal for a large garden or allotment.

  • It thrives in sun and well-drained soil, but needs some protection from the wind.

  • Alternatively, grow in a raised bed.

  • Asparagus is not suitable for containers, and will sulk if planted in heavy clay soils or in a shady spot.

  • Adding coarse sand to a clay soil helps create gaps between other soil components by allowing excess water to drain away and by creating air pockets that allow plant roots access to oxygen, water and nutrients.

  • However, too much sand can make soil dry and infertile.

How to grow Asparagus - Soil Preparation

  • If you can, start in autumn by thoroughly preparing the ground.

  • Ideally it should be excavated to a depth of 60cm (2 ft); if the soil has clay content put a layer of stone or broken bricks in the bottom to help with drainage, and mix sharp sand in with the soil backfill.

  • Mix in plenty of well-rotted farmyard manure, and removing all perennial weeds.

  • A week or so before planting, scatter some general fertilizer granules over the area (about 90g/sq m is ideal) and fork in, before raking the ground level.

  • A bed 1.5m (5ft) wide will allow the planting of three rows with 45cm (1ft 6in) between the rows and approximately 25cm (10in) between the plants.

  • If space is more limited a bed 1m (3ft) wide will accommodate two rows.

How to grow Asparagus - Planting Out

  • Asparagus can be grown from seed, although it’s easier and more rewarding for those who are less patient to grow asparagus from a one year-old crown – a ready-grown plant which you can buy from a garden centre or nursery.

  • Crowns weighing a minimum of 60gms (2oz) each should be planted now, in April.

  • Just prior to planting immerse the crowns in water to re-hydrate them. Excavate small trenches along the proposed line of planting, with the base 15cm below original ground level, lay the moist crowns in the trench and cover with soil.

  • The soil surface across the bed will be level with 13 to 15cm (five to six inches) of soil above all of the crowns.

  • As a rough guide, when the beds are in full production, each crown should produce 250gms (9oz) during the season.

How to grow Asparagus - Cultivation

  • Water newly planted crowns thoroughly and keep damp during dry weather.

  • Succulent spears may appear soon after planting, but avoid the temptation to harvest them or you'll weaken the crowns.

  • Cut down the stems in autumn, leaving 5cm (2in) stumps above the ground.

Asparagus ferns during the summer

  • To prevent competition, keep beds free of weeds.

  • Don’t harvest asparagus the first year after planting, but let the spears develop to fern and allow the plant time to grow and increase its root system, which in turn will play a vital role in storing adequate levels of carbohydrates, the fuel needed to produce the harvestable spears in future years.

  • Also as asparagus plants mature they have a tendency to rise out of the soil, so keep covering the crowns with compost each spring.

  • At the end of the first growing season, to encourage production of spears, you should cut back the tops of the asparagus foliage to the ground.

  • At this time, you may wish to dig up and remove the female plants, which produce smaller and fewer spears. These can be identified by the appearance of small red berries.

  • If you dig out the female plants, you can replace them in the spring with healthy male plants.

How to grow Asparagus - Harvesting

  • Most plants are ready to be picked two years after planting, although several modern varieties have been bred for earlier cropping.

  • In the second year after planting harvest for a short period, not exceeding two weeks and from year three harvest for six to eight weeks.

  • To harvest spears, wait until they're about 12cm long and remove them with a serrated knife, cutting them off 7cm beneath the soil.

  • Harvesting beyond mid-summer will shorten the life of the bed, and so stop then to allow the plants to build up their energy for next year, and you can give plants an extra boost by feeding with a general fertilizer.

How to grow Asparagus - Kitchen Notes

  • After all the hard work of getting the asparagus out of the ground, do it justice on the plate.

  • Cook it gently, as asparagus is one of the most nutritious vegetables you can eat.

  • The simplest recipes are often best.

  • Friends of asparagus are eggs, smoky crispy bacon, mozzarella, Parmesan and any crumbly cheese, chilli, cream, seafood, herbs such as mint, parsley, basil, rosemary.

  • Perhaps just eat asparagus with caper butter or anchovy butter melted on top, get your fingers messy and prepare to try your luck.