How to Grow Asparagus
Asparagus officinalis
A long-lived perennial needing a dedicated, sunny, free-draining bed. Plant crowns for a faster start (light picking in year 2) or from seed (year 3). Keep weeds down, water in dry spells, and mulch annually. Harvest spears for ~6–8 weeks each spring, stopping when new spears thin, then let fronds feed the crowns. Cut down the yellowed fern in autumn/winter and top with compost. Avoid waterlogging and do not overharvest young beds.
Yearly Lifecycle
Care Essentials
Early spring with a general fertiliser. Mulch with compost after cutting the fern back in autumn.
Watch For
- Asparagus beetle
- Slugs on emerging spears
- Violet root rot
- Fusarium
Companions
Tomatoes, Parsley, Basil, Marigolds
Care Requirements
Light
Full sun; sheltered from strong winds
Full sun is essential for strong spear production. Choose an open, sunny position sheltered from strong winds which can damage the tall fern.
Spacing
30cm apart in rows 45cm apart in trenches
Plant crowns 30cm apart in rows 45cm apart. Set crowns in trenches on a slight ridge. This is a long-term perennial bed, so correct spacing from the start is crucial.
Watering
Water in dry spells; consistent moisture helps
Water during dry spells, especially in the first two years while crowns establish. Consistent moisture during the growing season improves spear quality and fern health.
Fertilizing
Spring feed; autumn compost mulch after fern cut
Apply a general fertiliser in early spring before spears emerge. Mulch with compost after cutting the fern back in autumn to feed the soil and protect crowns.
Pruning
Cut yellowed fern in autumn; never cut green fern
Cut yellowed fern to ground level in autumn or early winter. Do not cut while still green — the fern photosynthesises to feed next year's crop.
Harvesting
Cut 15-20cm spears Apr-Jun; rest first two years
Cut spears at soil level when 15-20cm tall, from mid-April to mid-June. Stop harvesting after six to eight weeks to let fern grow. Do not harvest in the first two years.
Mulching
Autumn mulch with compost for feeding and protection
Mulch crowns in late autumn with well-rotted compost or manure. This feeds the soil, suppresses weeds, and provides extra winter protection for the crowns.
Growing Tips
Build a raised ridge
On heavy soils, plant crowns on shallow ridges in raised beds to secure drainage and warmer soil.
Plant crowns correctly
Spread roots like a star on the ridge and cover with 5–8 cm of soil; back-fill gradually as shoots emerge.
Easy does it on harvest
Don’t cut the first year; in year two, pick lightly for a few weeks, then up to 6–8 weeks thereafter.
Feed the factory
Once harvesting ends, allow fern to grow freely; it powers next spring’s crop.
Clean winter finish
When fronds yellow, cut them at the base and mulch to reduce overwintering pests.
Pests & Diseases
Pest Asparagus Beetle
Identification: Adults are 6–8mm with distinctive black and cream/red markings. Grey-green larvae and adults strip foliage from fern. Eggs are small, dark, and laid in rows on stems
- Pick off adults and larvae by hand — they drop when disturbed, so hold a container underneath
- Encourage natural predators such as ground beetles and parasitic wasps
- Cut and burn fern in autumn to destroy overwintering adults
- Spray with a contact insecticide containing pyrethrins when beetles or larvae are seen
Pest Slugs and Snails
Identification: Irregular holes and rasping damage on emerging spears; slime trails visible on and around the bed
- Use beer traps or copper tape barriers around the bed
- Apply organic slug pellets (ferric phosphate) as spears emerge
- Encourage hedgehogs, frogs, and ground beetles
- Apply slug pellets containing ferric phosphate around emerging spears
Disease Violet Root Rot Helicobasidium purpureum
Symptoms: Plants become stunted and yellow; roots are covered in a violet-purple fungal mat. Crowns rot and plants die
Treatment: There is no cure. Dig up and destroy affected plants. Do not replant asparagus in the same bed for at least 5 years
Prevention: Ensure excellent drainage. Avoid waterlogged soil. Rotate asparagus beds over long cycles
Disease Fusarium Crown and Root Rot Fusarium oxysporum f. sp. asparagi
Symptoms: Plants yellow and wilt; spears are thin and weak. Crowns show reddish-brown internal discolouration when cut open
Treatment: Remove and destroy affected plants. Do not replant asparagus in the same position
Prevention: Plant only certified disease-free crowns. Ensure good drainage. Avoid damaging crowns during cultivation
Disease Asparagus Rust Puccinia asparagi
Symptoms: Orange-brown pustules on fern stems and foliage from mid-summer; severe infections cause premature yellowing and defoliation
Treatment: Cut and burn affected fern in autumn. Improve air circulation around the bed
Prevention: Maintain good spacing. Cut and dispose of fern in autumn rather than composting. Choose resistant varieties where available
Popular Varieties
Green, Purple, White
Spacing & Planting
| Plant spacing | 30 cm |
| Row spacing | 45 cm |
| Mature height | 150 cm |
| Mature spread | 45 cm |
Planted as crowns in trenches. This is a long-term perennial bed, so proper spacing from the start is crucial for future spear production.
