Fertilising guide
How to fertilise King of Hearts Brunnera (Brunnera macrophylla 'King of Hearts')— schedule & NPK
Also called King of Hearts Siberian bugloss.
More about king of hearts brunnera
About King of Hearts Brunnera
Brunnera macrophylla 'King of Hearts' · also called King of Hearts Siberian bugloss · flowering
King of Hearts is a robust Siberian bugloss with large, heavily frosted silver leaves veined and edged in green, giving strong all-season shine in shade. Sprays of small blue forget-me-not flowers appear in spring. This clump-forming woodland perennial is more sun- and heat-tolerant than green forms but still needs cool, evenly moist soil.
Growth habit: Vigorous, clump-forming herbaceous perennial forming a dense mound of broad silver basal leaves, with sprays of blue flowers on wiry stems in mid to late spring.
What fertiliser king of hearts brunnera actually wants — and why
King of Hearts Brunnera 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 king of hearts brunnera: 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 king of hearts brunnera, 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 king of hearts brunnera:
Low-maintenance. An annual mulch of compost or leaf mould in spring usually covers its needs; a light balanced feed at growth start is optional. Avoid heavy nitrogen. 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 king of hearts brunnera 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 king of hearts brunnera
Half strength is the safe default for king of hearts brunnera — 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 king of hearts brunnera first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the king of hearts brunnera watering schedule.
Signs you are over-feeding king of hearts brunnera
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for king of hearts brunnera:
- 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 king of hearts brunnera
- 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 king of hearts brunnera care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of king of hearts brunnera 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 king of hearts brunnera
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 king of hearts brunnera — frequently asked questions
What fertiliser does king of hearts brunnera 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. King of Hearts Brunnera 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 king of hearts brunnera?
Low-maintenance. An annual mulch of compost or leaf mould in spring usually covers its needs; a light balanced feed at growth start is optional. Avoid heavy nitrogen. Low-maintenance. An annual mulch of compost or leaf mould in spring usually covers its needs; a light balanced feed at growth start is optional. Avoid heavy nitrogen. 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 king of hearts brunnera?
Half strength is the safe default for king of hearts brunnera — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding king of hearts brunnera 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 king of hearts brunnera 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 king of hearts brunnera?
Flush the pot of king of hearts brunnera 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
- King of Hearts Brunnera care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water king of hearts brunnera — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise peace lily
- How to fertilise bird of paradise
- How to fertilise hoya
- All 5561 fertilising guides in the Growli library