Allotment Growing

Growing Asparagus - How to Grow Asparagus

Growing asparagus is a long term project, slow to produce, expensive to start but really worthwhile when you harvest this delicious crop. It takes at least two years to come into production but then will continue for up to 20 years, repaying the initial investment many times over.

Because asparagus is grown in a permanent bed, it falls outside of rotation plans. It is more important because of this that the bed is well prepared.

Cultivating Asparagus

In the past it was recommended to grow them on a mounded bed but nowadays a raised deep bed is considered the best method.

The roots can go down 1.2 metres so a good depth of soil helps. It needs well drained soil but can be grown on heavier clays that have been well cultivated initially, contain plenty of humus and possibly some grit or sharp sand to open them up.

Starting Asparagus from Seed or Crown

You can start asparagus from seed but it is more usual to buy 1 year old crowns. These are planted 30- 45cm apart in April in a 30 cm wide trench about 20cm deep, slightly mounded in the centre so the roots slope downwards and out. In a standard raised bed, 1.2 metres wide, the trench goes down the centre. Cover with fine riddled soil to about 5cm above the top of the crown and then fill to the surface as the plant grows.

Asparagus plants are either male or female. The male plants are more productive and all male F1 hybrids are available with their energies going into edible spears rather than berries.

Keep the bed weed free, water as required but avoid it being too wet and do not take a crop in the first year. The plants are shallow so be careful if hoeing not to go deep, best hand weeded in a raised bed. The spears turn into foliage to feed the plant. In autumn the fern like foliage begins to yellow and should be cut off about 5 to 10cm above ground level.

In the spring draw up a ridge over the plant centre about 10cm high and add a balanced fertiliser like fish, blood and bone or Growmore. The spears start to appear in early May and there is no point in telling you not to take any, so just take a few leaving the rest to develop,

Cut the spears with a sharp knife some 7.5cm below the ground when they are about 10cm high above the ground. You can actually buy a special knife, especially shaped for cutting asparagus - Asparagus knife The real season starts in mid-May and runs through June when you must show restraint and stop cutting. In the second year just take 6 or 8 spears per plant, double that in the third year and expect about 20 to 25 spears per plant for the next 20 years.

Asparagus Problems

If a late frost strikes in May it will damage the crop so cover with fleece. Otherwise your main pest will be slugs although rust can be a problem in wet years. Remove affected shoots if rust strikes.

Asparagus Beetle

The asparagus beetle is rarely a problem to home growers. They are small with orange markings on their 7mm long bodies and will attack foliage and spears. Use an approved insecticide such as Derris.

Recommended Varieties of Asparagus to Grow

Gijnlim is an RHS Award of Garden Merit winner that has been a consistent top performer in recent European trials out yielding others by up to 25%. It's early too, giving the first succulent tasty spears in mid to late April and continuing to crop heavily until cutting ceases in July. Available as plants from Suttons

Resources

• Raised Deep Bed Gardening Pt 1 - About Raised or Deep Beds
• Raised Deep Bed Gardening Pt 2 - How to Construct Raised Deep Beds