Asparagus crowns planted in March give spears for twenty years

Plant asparagus crowns from early March to early April. That’s when nurseries send them out, and when the soil is starting to warm. Plant them as soon as they arrive, as the roots dry out quickly.

It’s a long wait for the first spears, two years at least, but a well-made bed crops every spring for twenty years or more. So the work goes into the bed before the crowns go in.

Choosing a spot

Asparagus wants full sun, good drainage and no perennial weeds. Couch grass, bindweed and docks are almost impossible to get out of an asparagus bed once it’s planted, so clear them completely first, ideally the year before.

On heavy clay, build a raised bed or plant on a low ridge to keep the crowns out of wet soil in winter. Choose a spot you won’t need to dig, as the bed stays put for decades. The ferns grow to around 1.5 m in summer, so put it where they won’t shade other crops.

Planting

1. Dig a trench about 30 cm wide and 20 cm deep, and fork plenty of well-rotted manure or compost into the bottom.
2. Make a ridge of soil about 10 cm high along the middle of the trench.
3. Set the crowns on the ridge, 40 cm apart, and spread the roots down either side like a spider’s legs.
4. Cover with soil so the tops of the crowns are about 10 cm below the surface.
5. Water in. Fill the trench in gradually as the shoots grow through the summer.

For more than one row, leave 45 cm between rows. Twenty crowns is a good number for a household that loves asparagus.

Tomatoes, parsley and basil grow well alongside. Keep it away from onions and garlic.

The first two years

Don’t cut any spears in the first year. Let them grow into ferns, which feed the crowns. Keep the bed weeded by hand, as hoeing can damage the shallow roots, and water in dry spells.

In autumn, when the ferns turn yellow, cut them down to about 5 cm and mulch the bed with compost or manure.

In the second spring, you can cut a few spears for two or three weeks, then let the rest grow.

Cutting spears

From the third year, cut spears from April until early June, about six to eight weeks. Cut them when they’re 15 to 18 cm tall, with a sharp knife about 2 cm below the soil. In warm weather, check every day or two, as spears grow fast.

Stop by early to mid-June, the traditional end being the longest day. The plants need the rest of the summer to build up the crowns for next year.

Common problems

Asparagus beetle. Small black and orange beetles and grey grubs stripping the ferns from late spring. Pick them off, and clear old ferns in autumn so they have nowhere to overwinter.

Slugs. They nibble emerging spears. Check the bed in damp weather.

Thin spears. The crowns are tired, overcut or hungry. Cut for a shorter season and feed the bed in spring.

Rhubarb is the other long-term crop worth planting now: see planting rhubarb crowns. Set your own frost dates on the asparagus page.