RHS Growing Guides

How to grow asparagus

Our detailed growing guide will help you with each step in successfully growing asparagus.

  1. Getting Started
  2. Choosing
  3. Preparing the Ground
  4. Sowing
  5. Planting
  6. Plant Care
  7. Harvesting
  8. Problems
1

Getting Started

Getting Started
Choosing
Section 1 of 8

Delicious, juicy asparagus spears are relatively easy to grow, and although you won’t get a crop for the first couple of years, after that you’ll have reliable harvests every spring for up to 20 years. 

Succulent, tasty asparagus spears can be harvested for about eight weeks every spring
Asparagus needs a sheltered site with free-draining soil, where it can grow on its own in a dedicated bed. It’s usually planted as dormant one-year-old plants known as crowns, but can also be grown from seed. Planting a new asparagus bed is an investment that will pay off in delicious harvests for years to come, but some initial patience is required – it’s best to let new plants get established for a few years before you cut your first spears.

Asparagus is harvested for about eight weeks in spring and early summer, so is an annual treat to be anticipated and savoured. Asparagus spears are also quite expensive to buy, so are well worth growing if you have the space. An established plant should produce about 10 spears per season. After the harvesting period, shoots should be left to grow into tall ferny plants over the rest of the summer. Then simply cut them down to the ground in autumn, and they will re-sprout in spring, ready for harvesting again. 

Related RHS Guides
Video: growing and harvesting asparagus

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2

Choosing

Getting Started
Preparing the Ground
Guide Start
Section 2 of 8

Different asparagus varieties produce spears of various sizes and colours
Asparagus is usually grown from ‘crowns’, or dormant roots – this is the easiest and fastest option, as they should settle in successfully and harvesting can begin after two years. Asparagus can also be grown from seed, but seedlings need more looking after and take longer to get established, so you should wait three years before harvesting. Still, seeds are cheaper than crowns.

Asparagus plants are either male or female – male plants produce more and better spears, so many modern varieties are all-male. Most crowns offered for sale are all-male F1 hybrids. Older, non-hybrid varieties produce both male and (less productive) female plants. The female plants also produce seedlings that need to be weeded out to prevent competition with the existing plants. Even all-male F1 seeds can produce the occasional female plant. 

When choosing varieties, also consider the quality of flavour, colour, spear size and overall harvest size. Some varieties produce early or late harvests, so if you grow several different varieties you can have spears over a longer period. For reliable cropping, look for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in our trials – see our list of AGM fruit and veg and our Recommended Varieties below. For more veg-growing inspiration, visit the RHS gardens, which all grow a wide range of vegetables, so you can compare varieties and pick up growing tips.

What and where to buy

Asparagus crowns (dormant one-year-old plants) are mainly available from online suppliers and can be ordered in advance for delivery in March or April, ready for immediate planting. These are usually supplied as ‘bare-root’ crowns (not in a pot), in packs of five or ten, rather than singly. Seeds can be bought in garden centres and from online seed retailers.  

Recommended Varieties

3

Preparing the Ground

Choosing
Sowing
Guide Start
Section 3 of 8

Create your asparagus bed in a warm, sunny, sheltered spot with free-draining soil
As asparagus plants can crop for about 20 years, it’s worth choosing your planting site carefully and preparing the ground well. This long-term crop needs a dedicated, permanent bed of several square metres/yards, depending on how many plants you want to grow (space them up to 45cm/18in apart). It’s best not to grow other plants or crops among asparagus, and don’t replant an old asparagus bed with new asparagus plants – choose fresh ground, to avoid any build-up of soil-borne problems. 

A planting site in full sun is preferable, but asparagus will also tolerate dappled shade. Most soil types are suitable, as long as they’re well drained. If you have heavy soil, make a raised bed to provide better drainage. A pH of 6.5–7.5 is ideal, so if your soil is more acidic than this, add lime to raise the pH. Weed the bed thoroughly before planting, then dig in at least a bucketful of organic matter, such as  garden compost or well-rotted manure, per square metre/yard. 

4

Sowing

Preparing the Ground
Planting
Guide Start
Section 4 of 8

The quickest and easiest way to start an asparagus bed is to buy bare-root crowns (see Planting below), but you can also grow asparagus from seed. Although seeds are a slower option and not quite as easy, they are cheaper to buy, and one packet could give you lots of plants. You can sow asparagus seeds either indoors or outside.

Sowing indoors

​Sow seeds indoors in February at 13–16°C (55–61°F). Fill a modular tray or small pots with moist, peat-free seed compost and sow one seed into each. For more sowing advice, see our guides below.

Related RHS Guides
Sowing seeds indoors – step by stepChoosing and using peat-free compost
Keep the seedlings warm and well watered, in a bright location. Start to harden them off after the last frost and prepare the ground as outlined above, ready for transplanting in early June – see Planting, below.

Sowing outdoors

Sow asparagus seeds outside in March or April. Choose and prepare the sowing site (see Preparing the ground, above), then sow the seeds thinly in a drill 2.5cm (1in) deep. Allow 30–45cm (12–18in) between rows. Thin out the seedlings to 15cm (6in) apart and protect from slugs and snails. Let the young plants get established for a year, then the following March either replant at their final spacing or transplant into their final growing site – see Planting, below, for full details.

Related RHS Guides
Sowing veg outdoorsSow outdoors – step by step
5

Planting

Sowing
Plant Care
Guide Start
Section 5 of 8
Enrich the soil with garden compost, then gently spread out the roots of each crown
Asparagus is usually planted as one-year-old, dormant plants called crowns. These are readily available by mail order, for delivery in March or April. Order early to get the widest choice of varieties. Crowns should be planted as soon as they arrive, ideally in March. If you’ve grown plants yourself from seed, they can planted in a similar way when they’re one year old.

Dig a trench 30cm (1ft) wide and 20cm (8in) deep. Fork garden compost or well-rotted manure into the base, then cover with a 5cm (2in) layer of the excavated soil. Make a ridge of soil along the centre of the trench, 10cm (4in) high. Place the crowns on top of this ridge, with the growing points or new shoots uppermost, spacing them 30–45cm (12–18in) apart. Spread the roots out evenly, but handle carefully as they break easily. Mix organic matter into the excavated trench soil, then gently return this enriched soil back into the trench, leaving the bud tips just visible. Space rows 45cm (18in) apart and stagger the plants between adjacent rows. Water the plants well, to settle to the soil around their roots, then mulch with a 5cm (2in) layer of well-rotted manure or garden compost, to hold in moisture and suppress weeds.
6

Plant Care

Planting
Harvesting
Guide Start
Section 6 of 8

Looking after established asparagus is straightforward – just weed regularly, apply mulch and put supports in place to keep these tall plants from being blown over. At the end of the season, when the foliage turns yellow, cut all the stems down to the base.

Let asparagus grow to full size over summer, then cut plants to the ground in autumn

Watering

Water new asparagus plants regularly throughout their first summer. Once established, asparagus is drought tolerant, so only needs to be watered in long dry spells. For water-wise advice, see our guides below.

Mulching

Apply a thick layer of mulch to the soil in late winter to discourage weed germination and hold moisture in the soil. You could also consider covering the soil with weed-suppressing membrane from autumn to late winter, while the asparagus is dormant, to prevent annual weeds germinating. It’s important not to let weeds get established in an asparagus bed, as removing large or widespread weeds can easily damage the shallow roots of asparagus plants.
​

Feeding

In most soils, established asparagus plants should crop reliably without additional feeding, especially if the soil is regularly mulched with organic matter. But if growth is poor, you could apply a high potassium general fertiliser in early spring, before the new spears sprout.

Weeding and removing female plants

​Keep the soil weed-free, as asparagus grows better without competition from other plants. Weed by hand rather than with a hoe, as asparagus plants have shallow roots that are easily damaged. If you have any female plants (which produce orange-red berries), weed out any seedlings they produce. If you’re growing an all-male variety, you may still find the occasional female plant, which you should remove.

Related RHS Guides
Controlling weeds

Supporting plants

Asparagus grows into a tall, feathery plant over the summer. To prevent the stems breaking in windy weather, which could damage the crown, support plants using stakes and twine to make a ‘fence’ either side of the row. You could also add netting, secured to the stakes about 50cm (20in) from the ground, for extra support.

Put stakes, string and netting in place early, to support asparagus plants as they grow

Propagating

To make more plants, you can divide well-established crowns in late winter or early spring. Do this no more than every three years, as the plants can be slow to settle back in afterwards. Dig up the crown, handling it carefully. Gently prise it apart into several smaller sections, each with several growing points, taking the strongest parts from the edge of the crown. It may be necessary to cut some roots if they can’t be pulled apart. Discard any old, woody parts. Replant the new sections straight away (see Planting, above), with the growth buds visible at the soil surface.

7

Harvesting

Plant Care
Problems
Guide Start
Section 7 of 8

Use a sharp knife to cut through the spears just below the soil surface
Freshly harvested asparagus spears have far more flavour than anything you can buy in the shops. But resist the temptation to harvest newly planted asparagus for the first two years (three if grown from seed), to let plants get well established. In the third year, harvest spears from mid-April for six weeks, then in subsequent years harvest for eight weeks.

To harvest, cut individual spears with a sharp knife 2.5cm (1in) below the soil surface when they’re no more than 18cm (7in) tall or about finger thickness. In warm weather, harvest every two to three days for the best quality spears – they grow quickly and soon turn woody. Regular harvesting also encourages more new shoots to be produced. Expect an established plant to provide about 10 spears over the harvesting period.

8

Problems

Harvesting
Guide Start
Section 8 of 8

Asparagus is generally trouble free, cropping reliably every spring. However, slugs, snails and asparagus beetles can cause problems, late frosts can damage young shoots in spring, and damp, poorly drained soil can cause the roots to rot. For tips on remedying these issues, see Common problems below.

Related RHS Guides
Controlling problems without chemicalsPreventing problems

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