Agapanthus: The ultimate guide to growing this summer stunner

Agapanthus, also known as the African lily or Lily of the Nile, is a stunning perennial that brings a touch of elegance to any garden. With its striking clusters of blue or white flowers on tall, sturdy stems, Agapanthus makes a dramatic focal point in borders, containers, or as a standalone feature.

Agapanthus flowers were a very familiar site in gardens and streetscapes when I lived in Australia, wherey they thrived. This tells you that they prefer warm climates, so they are not likely to be a huges success for you if you have cool summers.

Agapanthus are relatively easy to care for, thriving with proper attention to their specific needs. They are especially great for coastal gardens due to their salt spray tolerance and looks fantastic in mass plantings or lining pathways.

All about Agapanthus

Agapanthus is known for its ability to thrive in various conditions and its long flowering period, often blooming for several weeks in summer.

Key Agapanthus facts:

• Scientific name and any synonyms: Agapanthus africanus (formerly known as Crinum africanum)
• Meaning of scientific plant name: From Greek ‘agape’ (love) and ‘anthos’ (flower), meaning ‘flower of love’
• Common names: African lily, Lily of the Nile, African blue lily
• Plant family: Amaryllidaceae
• Place of origin of the plant: South Africa
• Type of plant: Herbaceous perennial
• Size: Typically 60-120 cm tall and 30-60 cm wide
• Foliage: Long, strap-like, arching green leaves
• Flower: Large spherical umbels of funnel-shaped flowers in shades of blue, purple, or white; blooms in summer
• Seeds: Capsules containing black, winged seeds; appear after flowering
• Toxicity: Mildly toxic to humans and pets if ingested, causing mouth irritation and digestive upset. The ASPCA lists Agapanthus as toxic to cats, dogs, and horses.

Growing Agapanthus in containers

Growing Agapanthus in containers is a wonderful way to enjoy these beautiful plants in a variety of garden settings. One of the main benefits is their adaptability; Agapanthus thrive in pots, making them perfect for patios, balconies, and small garden spaces.

To start, choose a container with good drainage and fill it with a well-draining potting mix. Agapanthus prefer a sunny location, so place your container where it will receive plenty of sunlight. Water the plant regularly, ensuring the soil stays moist but not waterlogged. During the growing season, feed your Agapanthus with a balanced fertiliser to encourage robust growth and abundant blooms.

Caring for container-grown Agapanthus is relatively straightforward. In colder climates, containers offer the advantage of mobility, allowing you to move the plants indoors or to a sheltered location during winter.

Deadhead spent flowers to promote continued blooming and prevent the plant from expending energy on seed production.

Don’t be too quick to consider re-potting or dividing the plant, even if the roots look congested. Agapanthus flower more vigorously when they have tightly packed roots. So don’t worry if they look like they are outgrowing the pot.

Care requirements

• Light requirements: Full sun to partial shade
• Water and humidity requirements: Regular watering, drought-tolerant once established
• Temperature requirements: -5°C to 35°C (23°F to 95°F); UK hardiness zone 8-10, US hardiness zone 7-11
• Soil requirements: Well-draining, fertile soil
• Feeding requirements: Annual feeding with balanced fertiliser in spring
• Propagation: Division, seed sowing
• Pruning: Remove spent flower heads and tidy foliage in autumn

Best Cultivars

1. ‘Midnight Blue’: Deep blue flowers, 1 m tall, vigorous grower
2. ‘Albus’: Pure white flowers, 80 cm tall, elegant appearance (pictured below)
3. ‘Peter Pan’: Dwarf variety with pale blue flowers, 40 cm tall, suitable for containers
4. ‘Queen Mum’: Bi-colour flowers with blue and white, 1.5 m tall, impressive size
5. ‘Navy Blue’: Dark blue-purple flowers, 1 m tall, rich colour
6. ‘Silver Moon’: Variegated foliage with cream edges, pale blue flowers, 60 cm tall
7. ‘Twister’: White flowers with blue bases, 60 cm tall, unique bi-colour effect (pictured below).

How to grow the Plant

Soil and Feeding

Agapanthus prefers well-draining, fertile soil. A mix of loam, sand, and organic matter works well. Add compost or well-rotted manure to improve soil structure and fertility. In spring, apply a balanced, slow-release fertiliser.

During the growing season, you can supplement with a liquid fertiliser high in potassium to encourage flowering. Avoid over-fertilising, as this can lead to lush foliage at the expense of blooms.

Watering

Water regularly during the growing season, especially when plants are establishing. Once established, Agapanthus is relatively drought-tolerant but benefits from consistent moisture.

Water deeply and less frequently to encourage deep root growth. Avoid waterlogging, as this can lead to root rot. In containers, ensure proper drainage and water more frequently, especially during hot spells.

Pruning

Prune Agapanthus after flowering to maintain its shape and promote healthy growth. Cut back flower stems to the base once blooms have faded. In autumn, tidy the foliage by removing any dead or yellowing leaves.

For evergreen varieties in milder climates, leave the foliage intact over winter for protection. In colder areas, cut back deciduous varieties to ground level and provide winter protection with mulch.

Propagation

The most common method of propagating Agapanthus is by division. However, as noted, don’t rush to divide Agapanthus just because the plant has congested roots, as this helps them flower well – especially in containers.

Here’s a step-by-step guide:

1. In spring or early autumn, lift the entire plant from the ground.
2. Shake off excess soil to expose the root system.
3. Using a sharp, clean knife, divide the clump into sections, ensuring each has several healthy shoots and roots.
4. Replant the divisions immediately at the same depth as they were previously growing.
5. Water well and keep moist until established.

Alternatively, sow seeds in spring, but note that this method is slower and may not produce plants true to the parent.

Common Problems & Solutions

• Snails and slugs: These pests can damage young shoots and leaves. Use organic slug pellets or beer traps to control them.
• Agapanthus gall midge: Causes distorted buds that fail to open. Remove and destroy affected buds promptly.
• Root rot: Caused by overwatering or poor drainage. Ensure well-draining soil and avoid waterlogging.
• Leaf spot: Fungal disease causing brown spots on leaves. Remove affected foliage and improve air circulation.
• Lack of flowers: Often due to overcrowding or insufficient sunlight. Divide plants or move to a sunnier location.
• Frost damage: Protect plants in winter with mulch or move container plants to a sheltered location.
• Yellowing leaves: May indicate nutrient deficiency or overwatering. Adjust feeding and watering practices accordingly.