Fertilising guide

How to fertilise Agapanthus africanus 'Albus' (Agapanthus africanus 'Albus')— schedule & NPK

Also called white African lily, white agapanthus.

More about agapanthus africanus 'albus'

About Agapanthus africanus 'Albus'

Agapanthus africanus 'Albus' · also called white African lily, white agapanthus · flowering

Agapanthus africanus 'Albus' is the white-flowered form of the evergreen African lily, bearing rounded heads of pure white trumpet blooms on stout stems in summer above glossy, strap-shaped leaves. Being evergreen and tender, it needs frost protection in cool climates and is best grown in containers that can be moved under cover for winter.

Growth habit: Evergreen, clump-forming perennial with broad, glossy, arching strap-leaves retained year-round and tall scapes topped by spherical white flower heads.

Watch for — Poor flowering: Caused by shade, over-potting, or too much nitrogen. Provide full sun, keep roots slightly restricted, and feed with high-potash fertiliser.

What fertiliser agapanthus africanus 'albus' actually wants — and why

Agapanthus africanus 'Albus' is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.

A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom.

For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for agapanthus africanus 'albus': match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.

How often to feed agapanthus africanus 'albus', and which months

Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For agapanthus africanus 'albus':

Feed every 2 weeks from spring to flowering with a high-potash liquid feed such as tomato fertiliser to maximise the white blooms; reduce in late summer and stop over winter. Skip high-nitrogen feeds, which suppress flowering. For a hungry bloomer that means feeding regularly — every 2 weeks — right through flowering across the main season (spring through early autumn), tapering as blooming ends.

The dormant-season rule matters more than the exact interval: skip feeding entirely when agapanthus africanus 'albus' is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.

What strength to mix for agapanthus africanus 'albus'

Follow the flowering-feed label rate for agapanthus africanus 'albus', or half strength if feeding very frequently. These plants genuinely use the nutrients — under-feeding shows up fast as a thin display.

Feeding always goes onto already-damp soil, never dry roots — water agapanthus africanus 'albus' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the agapanthus africanus 'albus' watering schedule.

Signs you are over-feeding agapanthus africanus 'albus'

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for agapanthus africanus 'albus':

Lots of lush leaves but few flowers (too much nitrogen).
Scorched leaf edges and salt crust from too-strong or too-frequent feeds.
Soft, sappy growth prone to aphids and mildew.

Signs you are under-feeding agapanthus africanus 'albus'

Sparse, small, short-lived flowers and pale foliage.
A tired plant that stops blooming early in the season.
Weak growth and poor repeat-flowering after the first flush.

If the symptoms point at watering, light or roots rather than nutrition, the full agapanthus africanus 'albus' care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Container-grown agapanthus africanus 'albus' accumulates feed salts fast with frequent feeding — water until it drains each time and flush pots with plain water every few weeks to prevent scorch.

Organic vs synthetic feeds for agapanthus africanus 'albus'

Organic options

A liquid comfrey or seaweed feed (naturally potassium-rich) plus compost or well-rotted manure as a mulch. UK: comfrey feed, organic Tomorite, or rose feed; US: Espoma Rose-tone or Neptune's Harvest. Feeds and improves soil.

Synthetic / liquid feeds

A high-potash flowering feed on a regular cadence — UK: Tomorite (Levington), Phostrogen or a specialist rose feed; US: Miracle-Gro Bloom Booster or a rose food. Fast, reliable bloom response.

Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.

Fertilising agapanthus africanus 'albus' — frequently asked questions

What fertiliser does agapanthus africanus 'albus' need?

A high-potassium ("high-potash") flowering feed — tomato-style or a dedicated bloom/rose feed. Potassium powers flowering; a high-nitrogen feed gives you a leafy plant with disappointing bloom. Agapanthus africanus 'Albus' is a heavy-blooming flower with a big appetite — a regular high-potash feed through the season is what drives a long, dense display.

How often should I feed agapanthus africanus 'albus'?

Feed every 2 weeks from spring to flowering with a high-potash liquid feed such as tomato fertiliser to maximise the white blooms; reduce in late summer and stop over winter. Skip high-nitrogen feeds, which suppress flowering. Feed every 2 weeks from spring to flowering with a high-potash liquid feed such as tomato fertiliser to maximise the white blooms; reduce in late summer and stop over winter. Skip high-nitrogen feeds, which suppress flowering. For a hungry bloomer that means feeding regularly — every 2 weeks — right through flowering across the main season (spring through early autumn), tapering as blooming ends.

What strength of feed for agapanthus africanus 'albus'?

What does over-feeding agapanthus africanus 'albus' look like?

Lots of lush leaves but few flowers (too much nitrogen). Scorched leaf edges and salt crust from too-strong or too-frequent feeds. Soft, sappy growth prone to aphids and mildew. Using a high-nitrogen general feed on agapanthus africanus 'albus' is the headline mistake — you grow a big leafy plant with few flowers. The second is simply under-feeding a genuinely hungry bloomer and getting a sparse, short display.

Should I flush the soil of agapanthus africanus 'albus'?