Fertilising guide
How to fertilise Brunnera macrophylla 'Looking Glass' (Brunnera macrophylla 'Looking Glass')— schedule & NPK
Also called Looking Glass brunnera.
More about brunnera macrophylla 'looking glass'
About Brunnera macrophylla 'Looking Glass'
Brunnera macrophylla 'Looking Glass' · also called Looking Glass brunnera · flowering
A dazzling sport of 'Jack Frost' with almost entirely silver, metallic heart-shaped leaves showing only faint green veining. Sprays of sky-blue forget-me-not flowers rise above the shimmering foliage in spring. This clump-forming shade perennial brightens dark woodland corners like a mirror, but its near-white leaves are more prone to sun scorch than greener types.
Growth habit: Clump-forming, slowly spreading herbaceous perennial forming mounds of near-silver heart-shaped foliage, with airy blue flower sprays in spring. Foliage holds through the season.
Watch for — Wilting in dry heat: Pale foliage loses moisture fast and wilts. Maintain steady soil moisture and mulch heavily.
What fertiliser brunnera macrophylla 'looking glass' actually wants — and why
Brunnera macrophylla 'Looking Glass' is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
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 brunnera macrophylla 'looking glass': 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 brunnera macrophylla 'looking glass', 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 brunnera macrophylla 'looking glass':
Light feeder. A spring top-dressing of compost or one application of balanced slow-release fertiliser suffices. No heavy feeding is needed for this woodland groundcover. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when brunnera macrophylla 'looking glass' 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 brunnera macrophylla 'looking glass'
Half strength is the safe default for brunnera macrophylla 'looking glass' — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water brunnera macrophylla 'looking glass' first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the brunnera macrophylla 'looking glass' watering schedule.
Signs you are over-feeding brunnera macrophylla 'looking glass'
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for brunnera macrophylla 'looking glass':
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding brunnera macrophylla 'looking glass'
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full brunnera macrophylla 'looking glass' care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of brunnera macrophylla 'looking glass' with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for brunnera macrophylla 'looking glass'
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
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 brunnera macrophylla 'looking glass' — frequently asked questions
What fertiliser does brunnera macrophylla 'looking glass' need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Brunnera macrophylla 'Looking Glass' is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed brunnera macrophylla 'looking glass'?
Light feeder. A spring top-dressing of compost or one application of balanced slow-release fertiliser suffices. No heavy feeding is needed for this woodland groundcover. Light feeder. A spring top-dressing of compost or one application of balanced slow-release fertiliser suffices. No heavy feeding is needed for this woodland groundcover. Treat that as sparingly through the growing season between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for brunnera macrophylla 'looking glass'?
Half strength is the safe default for brunnera macrophylla 'looking glass' — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding brunnera macrophylla 'looking glass' look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding brunnera macrophylla 'looking glass' year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of brunnera macrophylla 'looking glass'?
Flush the pot of brunnera macrophylla 'looking glass' with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Brunnera macrophylla 'Looking Glass' care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water brunnera macrophylla 'looking glass' — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
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- All 2464 fertilising guides in the Growli library