Grow your own: Asparagus

Mar 3, 2023

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Asparagus is one of the few perennial vegetables (those which come up year after year) and is one of the most highly prized – a true delicacy.

It grows from thick spidery roots which act as the storage organs in winter when the plant dies back. In early spring the first young shoots to grow from these roots are harvested as the asparagus spears that we so love to eat.

These are severed from the plant at soil level and those remaining are allowed to grow into ferny stems. Being expensive to buy, growing your own asparagus is worthwhile, and with very few pest and disease problems it is not too difficult.

Asparagus calendar

Asparagus can be sown between March and May. It is a long-term crop. Harvest between April and June.

Asparagus growing calendar. The table shows that asparagus should be sown between March and May, in the ground year round, and harvested between April and June.

Asparagus varieties

‘Paciﬁc Purple’
Sweet and stringless. Steam to retain the purple colour. Plant autumn.
‘Purple Passion’
A popular variety producing heavy crops of sweet spears. Plant spring.
‘Connover’s Colossal’
A good early cropping variety that is also available as seed. Plant spring
‘Gijnlim’
An early heavy yielding variety producing thick, tender spears. Plant spring.

Sowing & growing asparagus

Asparagus is a long-term crop so it pays to get the site in order well before planting. This means removing all perennial weeds, which will otherwise quickly colonise the bed.

Asparagus likes a sunny site that is well drained, also add some farmyard manure or garden compost. The spidery roots are usually bought in the dormant season and planted in early spring.

The roots are placed in a trench about 30cm (12in) wide and 20cm (8in) deep. Splay the roots out over a slight hump in the bottom of the trench. Cover with about 5cm (2in) of soil and firm down.

Growing on & harvesting asparagus

In the first year some spears will appear but avoid cutting these as you want them to grow, producing the feathery stems. These will put on lots of good growth in the first year and then you can take a small harvest off the following spring and gradually increase the amount you take as the plants establish.

Always keep the beds weed-free but avoid hoeing in the early spring as you will cut off the spears. Once you start harvesting, around May time, then continue for a couple of weeks but stop by early to mid June and allow the shoots to develop and grow into the feathery stems.

If you don’t let these grow, the crowns will weaken and fewer shoots will form the following spring. The foliage of asparagus is fern-like and quite spindly so will benefit from being supported with string around the outside to keep it growing straight and upright.

In autumn the foliage will start to yellow and can then be removed, cutting at the base. Leave 3cm (1in) stumps above ground. In late winter apply a little Growmore and if you have some compost place some over the beds.