Fertilising guide

How to fertilise Large-flowered Bacopa (Sutera grandiflora)— schedule & NPK

Also called Large-flowered Bacopa, Purple Glory Plant, Bacopa.

More about large-flowered bacopa

About Large-flowered Bacopa

Sutera grandiflora · also called Large-flowered Bacopa, Purple Glory Plant · flowering

Sutera grandiflora, known as the purple glory plant or large-flowered bacopa, is a tender evergreen perennial from South Africa, producing a profusion of five-petalled, lilac to purple flowers considerably larger than those of the familiar trailing bacopa (Chaenostoma cordatum). It thrives in full sun with reliably moist, free-draining soil and is frost-tender, grown as a container plant or annual in most of the UK. The single most important care point is consistent watering: plants drop buds quickly when stressed by drought, and unlike many plants they do not wilt as a visible warning signal. It is not listed in the ASPCA database, so a precautionary mildly-toxic classification applies.

Growth habit: Bushy, semi-trailing evergreen perennial with a spreading to mounding habit.

What fertiliser large-flowered bacopa actually wants — and why

Large-flowered Bacopa 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 large-flowered bacopa: 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 large-flowered bacopa, 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 large-flowered bacopa:

Feed every one to two weeks with a balanced liquid fertiliser (10-10-10) during the growing season; switch to a high-potash feed in late summer to encourage continued flowering. For a hungry bloomer that means feeding regularly — sparingly through the growing season — 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 large-flowered bacopa 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 large-flowered bacopa

Follow the flowering-feed label rate for large-flowered bacopa, 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 large-flowered bacopa first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the large-flowered bacopa watering schedule.

Signs you are over-feeding large-flowered bacopa

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for large-flowered bacopa:

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 large-flowered bacopa

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 large-flowered bacopa care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Container-grown large-flowered bacopa 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 large-flowered bacopa

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 large-flowered bacopa — frequently asked questions

What fertiliser does large-flowered bacopa 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. Large-flowered Bacopa 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 large-flowered bacopa?

Feed every one to two weeks with a balanced liquid fertiliser (10-10-10) during the growing season; switch to a high-potash feed in late summer to encourage continued flowering. Feed every one to two weeks with a balanced liquid fertiliser (10-10-10) during the growing season; switch to a high-potash feed in late summer to encourage continued flowering. For a hungry bloomer that means feeding regularly — sparingly through the growing season — right through flowering across the main season (spring through early autumn), tapering as blooming ends.

What strength of feed for large-flowered bacopa?

What does over-feeding large-flowered bacopa 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 large-flowered bacopa 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 large-flowered bacopa?