Description
Asparagus Purple
Asparagus ‘Purple’ (Asparagus officinalis) is a vibrant, long-lived variety grown from crowns for quicker establishment. It produces uniform, medium-thick spears with deep purple skin, pale green flesh, and a naturally sweet, tender texture. With lower fibre and higher natural sugars than green types, the spears have a mild, earthy flavour with subtle nutty notes—perfect for eating raw or lightly cooked. When cooked, the purple colour fades to green, so enjoy raw or lightly blanched if you wish to retain its rich hue. This productive variety delivers abundant harvests that increase as the crowns mature.
Native to Europe, northern Africa, and parts of Asia, asparagus thrives in regions with cool winters and mild summers. While green varieties may offer slightly more calcium and vitamins A and C, purple asparagus is still rich in fibre, folate, and antioxidants. Light harvesting may begin in the second year, but waiting until the third allows for stronger long-term yields.
Climate & Site Selection
Asparagus grows well in cool to subtropical climates. It performs best in full sun with some light afternoon shade in hotter regions. Choose a permanent location with deep, fertile, free-draining soil enriched with compost or aged manure. A neutral to slightly alkaline pH (6.5–7.5) is ideal.
Because asparagus can remain productive for 15–20 years, it should be planted in a permanent area with good drainage, away from spots likely to be disturbed. Raised beds are especially beneficial in heavier soils or poorly draining locations.
Growing Asparagus in Pots
Asparagus can be grown in containers, including deep pots or large trough-style planters, as long as they provide enough space for long-term root growth. As a perennial, it prefers to stay undisturbed, so choose a container that allows the crown to remain in place for several years. While container-grown plants may produce for a few seasons, yields often decline as space becomes limited, especially in smaller pots.
Keep soil consistently moist, fertilise after harvest, and mulch the surface in winter. In frost-prone areas, insulate smaller pots or move them to a sheltered spot. Larger containers offer better protection, but surface mulching still helps safeguard dormant crowns.
When to Plant
In warmer climates, crowns can be planted in winter; in cooler regions, wait until late winter to early spring when the soil is workable and not waterlogged.
If not planting immediately, store in a cool, dry, well-ventilated place (e.g. cupboard or garage). Keep the crowns in their original net bag or a breathable box without soil or moisture. Check them regularly and plant within a few weeks. Light mould on the roots may occasionally appear during storage or transit — this is not harmful and can be simply rubbed off before planting.
How to Plant
1. Remove weeds and enrich the soil with compost or aged manure. Add balanced fertiliser.
2. Dig trenches 25–30 cm deep, 30 cm wide.
3. Make a mound in the trench base and spread roots over it.
4. Space crowns 60 cm apart; allow 1.2–1.5 m between rows (or 90 cm–1 m in raised beds).
5. Cover the crowns with 5 cm of soil and water.
6. As shoots appear, gradually backfill, keeping tips exposed.
7. Mulch to conserve moisture, regulate temperature, and suppress weeds.
Life Cycle
• Year 1: No harvest. Let all spears grow into ferns.
• Year 2: Lightly harvest thicker spears for 2 weeks. Allow the rest to fern out.
• Year 3+: Harvest for 4–6 weeks, with the harvest period gradually extending up to 8 weeks or more as plants mature. Stop once spears are thin below pencil size to allow the crown to recover.
Supporting Ferns
By summer, ferns grow tall and may lean or snap in the wind. Support with stakes, twine, or a trellis to prevent damage and reduce disease.
Care & Maintenance
Keep beds free of weeds, ideally by hand, to protect the roots. Water deeply and consistently, especially during active growth and in dry conditions. After the final harvest, fertilise to support strong fern growth. Once the ferns have fully yellowed and dried out—usually in late autumn or winter—they can be cut back to just above ground level to tidy the bed and reduce pest and disease risk. Refresh mulch in winter to help insulate crowns in cooler areas and shield roots from heat in warmer regions.
Seasonal Care
• Spring: Spears emerge; begin harvest.
• Summer: Spears grow into ferns; leave them intact.
• Autumn: Ferns yellow; cut back when fully browned.
• Winter: Dormant. Mulch and compost. Divide if needed.
Harvesting
Begin light harvesting in the second year, taking only the thicker spears over a short two-week period. In the third year, moderate harvesting can begin, typically lasting 4–6 weeks and extending up to 8 weeks or more as plants mature. Spears emerge in spring and should be cut when 15–20 cm tall and pencil-thick. Check plants every few days during peak growth to avoid spears becoming woody. Reduce watering near the end of the harvest period and stop completely around two weeks before the final harvest. Yellowing, floppy spear tips indicate the plant is entering dormancy.
Division
Divide crowns every 8–10 years in winter if growth declines or plants are overcrowded. Use a sharp spade and replant immediately.
Pests & Diseases
• Slugs/snails: Common in wet weather. Use traps or barriers.
• Crown rot: Avoid waterlogged soil.
• Rust/Fusarium: Improve airflow, remove affected ferns, and don’t replant in infected soil.
Companion Planting
Grow asparagus in its own bed. Strawberries nearby make good companions and attract beneficial insects. Avoid planting shallots or other alliums too close, as they may compete for nutrients.
Safety
Only the spears are edible. The ferns may produce small red berries, which are poisonous if eaten. Keep children and pets supervised around the plants. If any part other than the spears is consumed, seek medical or veterinary advice immediately.
Supplied as dormant crowns.