Allotment ProYour allotment, organised

Private by default. No third-party analytics.

Asparagus

This Allotment Pro editorial draft summarises the cited RHS guide. Check the source and adjust timings for local conditions.
RHS source guide
Asparagus crop illustration

Month by month

Sow

  1. FebruaryIndoors · Module Sow

    Sow one seed per module or small pot at 13–16°C (55–61°F).

  2. March–AprilOutdoors · Direct Sow

    Sow thinly in prepared ground.

Plant

  1. March–AprilOutdoors · Crown

    Plant crowns promptly on arrival; March is ideal, while suppliers may deliver in March or April.

Transplant

  1. JuneOutdoors · Transplant

    Move hardened-off indoor-sown seedlings into their prepared bed in early June.

Harvest

  1. April–JuneOutdoors · Cut

    From the third year, begin in mid-April: cut for six weeks that year and for eight weeks in later years.

1

1 - Getting Started

A dedicated asparagus bed takes patience at first but can then give dependable spring crops for many years. Crowns are the usual starting material, while seed offers a lower-cost but slower route.

Growth and cropping pattern

Allow young plants to build strength before harvesting. Once the cutting period ends, leave the shoots to develop into tall, fern-like summer growth, then remove the yellowed stems in autumn so fresh spears can emerge the following spring.

Key measurements and instructions

  • The guide says a well-established bed can remain productive for up to this long: 20 years (Outdoors).
  • Approximate annual cutting period in spring and early summer once plants are established: 8 weeks (Outdoors · Cut).
  • Approximate expected output over the harvest period: 10 spears per season (Outdoors · Cut).
2

2 - Choosing What To Grow

Crowns establish more readily and reach harvest sooner than seed-grown plants. Variety choice can be based on flavour, spear colour and thickness, crop size and whether cropping is early or late.

Crowns or seed

Dormant one-year-old crowns are the easiest and fastest option. Seed is cheaper and may produce many plants, but seedlings demand more care and an extra year before the first harvest.

  • Wait before harvesting plants established from crowns: 2 years (Outdoors · Crown).
  • Wait before harvesting plants raised from seed: 3 years (Outdoors · Seed).

Male and female plants

Male plants give more and better spears, so many modern F1 cultivars are all-male. Older non-hybrid cultivars include both sexes; female plants are less productive and their seedlings can compete with the established bed.

Buying plants

Order dormant bare-root crowns early for the broadest choice and plant them when delivered in March or April. They are commonly sold online in packs, while some garden centres also stock crowns; seed is available from garden centres and online retailers.

  • Typical pack sizes stated by the guide: 5 or 10 crowns (Outdoors · Crown).

Recommended varieties

3

3 - Preparing The Ground

Choose a warm, sheltered position with free drainage and reserve it for asparagus. Prepare fresh ground rather than replanting an old asparagus bed, which helps avoid accumulated soil-borne problems.

Site and spacing

Full sun is preferred, although dappled shade is tolerated. Most soils are suitable if they drain freely; on heavy ground, use a raised bed. Do not interplant the permanent bed with other crops.

  • Up to 18in between plants when planning the bed: 45 cm (Outdoors).

Soil preparation

Clear weeds before planting. Either work compost or well-rotted manure into the ground, or use a no-dig approach by spreading organic mulch and planting through it.

  • The guide specifies at least this amount of organic matter; the equivalent area wording is per square yard: 1 bucketful per square metre (Outdoors).
4

4 - Sowing

Seed is slower than planting crowns but is economical and can be started in warmth or sown directly outside.

Sowing indoors

In February, sow one seed into each module or small pot of moist peat-free seed compost. Keep seedlings warm, bright and watered, then harden them after the last frost and prepare to transplant in early June.

  • Equivalent to 55–61°F: 13–16 °C (Indoors · Module Sow).
  • Also applies to each small pot: 1 seed (Indoors · Module Sow).

Sowing outdoors

Direct-sow thinly in March or April. Protect seedlings from slugs and snails, let them establish for a year, then move them to final positions the following March.

  • Equivalent to 1in; sow in a shallow drill: 2.5 cm (Outdoors · Direct Sow).
  • Equivalent to 12–18in between rows: 30–45 cm (Outdoors · Direct Sow).
  • Equivalent to 6in between seedlings after thinning: 15 cm (Outdoors · Direct Sow).
5

5 - Planting

Plant crowns promptly, preferably in March. Spread their fragile roots carefully over a low soil mound, leave the growth tips visible, water thoroughly and finish with organic mulch.

Planting crowns and young plants

Set crowns or one-year-old seed-raised plants in staggered rows. A trench may be more practical than individual holes for a full bed. Position each crown with shoots uppermost, spread the roots evenly and gently return the soil around them.

  • Equivalent to 12–18in between plants: 30–45 cm (Outdoors · Crown).
  • Equivalent to 18in; stagger plants in neighbouring rows: 45 cm (Outdoors · Crown).
  • Approximate width, equivalent to 1ft, allowing roots to spread: 30 cm (Outdoors · Crown).
  • Approximate depth, equivalent to 8in: 20 cm (Outdoors · Crown).
  • Approximate central mound height, equivalent to 4in: 10 cm (Outdoors · Crown).
  • Equivalent to 2in of well-rotted manure or garden compost after watering: 5 cm (Outdoors · Crown).

Growing asparagus in pots

Where ground space is unavailable, plant one crown in a large container of good peat-free compost. Water regularly, support the summer growth, apply balanced liquid feed during active growth and top-dress each spring. Container plants are shorter-lived and produce smaller crops for only a few years.

  • Equivalent to 1ft: 30 cm (Container · Crown).
  • Equivalent to 1ft: 30 cm (Container · Crown).
  • Place centrally in each pot: 1 crown (Container · Crown).
6

6 - Plant Care

Established asparagus mainly needs weed control, an annual mulch, support for its tall summer stems and removal of yellow foliage at the end of the season.

Watering

Water new plants regularly throughout their first summer. Established plants cope with drought and generally need irrigation only during prolonged dry weather.

Mulching and feeding

Apply a generous organic mulch in late winter each year to retain moisture and limit weeds. A biodegradable weed-suppressing membrane may be used from autumn to late winter while plants are dormant. Regularly mulched plants usually need no extra feed; if growth is weak, apply a general fertiliser before spring spears appear.

Weeding

Keep the bed weed-free, but work by hand because hoeing or removing established weeds can injure the shallow asparagus roots. Remove seedlings arising from orange-red berries on female plants so they do not compete with the crop.

Supporting plants

Protect the tall, feathery summer stems from wind damage by placing stakes and twine along both sides of each row. Netting fixed to the stakes can add further support.

  • Equivalent to 20in above the ground: 50 cm (Outdoors · Support).

Propagating by division

In late winter or early spring, gaps can be filled by dividing a mature crown into strong outer sections, each carrying several growth points. Remove old woody pieces and replant divisions immediately with their buds visible at the surface.

  • Do not divide more frequently because plants may re-establish slowly: 3 years (Outdoors · Division).
7

7 - Harvesting

Do not cut newly planted asparagus during its first two years, or its first three years when seed-grown. Start a short harvest in year three, then use the full cutting period in following seasons.

When and how to cut spears

From mid-April in the third year, harvest for six weeks; in later years, continue for eight weeks. Cut each suitable spear just below soil level. During warm weather, pick frequently because stems soon become woody, and regular cutting promotes further shoots.

  • Begin in mid-April in the third year: 6 weeks (Outdoors · Cut).
  • Annual cutting period after the third year: 8 weeks (Outdoors · Cut).
  • Equivalent to 1in below the soil surface; use a sharp knife: 2.5 cm (Outdoors · Cut).
  • Equivalent to 7in; cut when no taller than this or around finger thickness: 18 cm (Outdoors · Cut).
  • Recommended picking frequency in warm weather for good spear quality: 2–3 days (Outdoors · Cut).
8

8 - Problem Solving

Asparagus is usually dependable, but young spears may be damaged by frost, slugs or snails, while asparagus beetles feed on summer growth. Waterlogged ground can also lead to root decay, making good drainage important.

The guide highlights frost injury, asparagus beetle and slugs and snails, with dedicated RHS problem pages for identification and control advice.

Common problems

Frost damage

Late frost can injure tender new asparagus shoots in spring.

Problem source

Asparagus beetle

Adults and larvae eat asparagus stems and foliage in summer, and severe leaf loss can weaken the plants.

Problem source

Slugs and snails

Slugs and snails may damage asparagus, particularly young seedlings and emerging growth.

Problem source