Fertilising guide
How to fertilise Bog rosemary (Andromeda polifolia)— schedule & NPK
Also called Bog rosemary, Marsh andromeda.
More about bog rosemary
About Bog rosemary
Andromeda polifolia · also called Bog rosemary, Marsh andromeda · flowering
Bog rosemary is a compact evergreen subshrub native to Northern Hemisphere bogs and tundra. Its narrow, grey-green leaves resemble rosemary and it bears delicate pink urn-shaped flowers in spring. Suited to acidic, permanently moist conditions in rock gardens or bog plantings, it is fully hardy and tolerates challenging cold climates.
Growth habit: Low, spreading evergreen subshrub with wiry stems
What fertiliser bog rosemary actually wants — and why
Bog rosemary is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves.
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 bog rosemary: 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 bog rosemary, 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 bog rosemary:
Fertilise sparingly with a dilute ericaceous liquid feed in early spring. Bog rosemary is adapted to nutrient-poor conditions; excessive feeding causes soft growth and root damage. A single application at quarter strength annually is typically sufficient. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
The dormant-season rule matters more than the exact interval: skip feeding entirely when bog rosemary 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 bog rosemary
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for bog rosemary. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water bog rosemary first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the bog rosemary watering schedule.
Signs you are over-feeding bog rosemary
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for bog rosemary:
- Brown, scorched leaf margins from too strong or too frequent a dose.
- White salt crust on the soil surface.
- Soft, lush growth that fruits or flowers poorly.
Signs you are under-feeding bog rosemary
- Yellowing leaves with green veins (iron chlorosis from high pH).
- Weak growth, poor cropping and an overall pale, stressed look.
- Stunted new shoots in spring despite adequate water and light.
If the symptoms point at watering, light or roots rather than nutrition, the full bog rosemary care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush bog rosemary with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Organic vs synthetic feeds for bog rosemary
Organic options
Composted pine bark, pine-needle mulch, used coffee grounds and an organic ericaceous feed gently maintain acidity. UK: Vitax or Westland Ericaceous; US: Espoma Holly-tone or Dr. Earth Acid Lovers. Slow, soil-improving, hard to overdo.
Synthetic / liquid feeds
A liquid or granular ericaceous feed — UK: Miracle-Gro Ericaceous, Vitax or Westland; US: Miracle-Gro Acid-Loving Plant Food or Espoma Holly-tone. Pair with rainwater and an acidic mulch for it to work.
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 bog rosemary — frequently asked questions
What fertiliser does bog rosemary need?
An ericaceous (acidic) fertiliser, formulated to keep the soil pH low and supply iron and trace elements in a form acid-loving roots can absorb. Ordinary feeds and any lime lock out iron and yellow the leaves. Bog rosemary is an acid-loving plant — it can only take up nutrients in acidic soil, so the feed itself matters less than using an ericaceous formula and never liming.
How often should I feed bog rosemary?
Fertilise sparingly with a dilute ericaceous liquid feed in early spring. Bog rosemary is adapted to nutrient-poor conditions; excessive feeding causes soft growth and root damage. A single application at quarter strength annually is typically sufficient. Fertilise sparingly with a dilute ericaceous liquid feed in early spring. Bog rosemary is adapted to nutrient-poor conditions; excessive feeding causes soft growth and root damage. A single application at quarter strength annually is typically sufficient. In practice: an ericaceous feed in spring as growth resumes, repeated through the main growing months; never apply lime, bonemeal or wood ash, which raise pH.
What strength of feed for bog rosemary?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for bog rosemary. The variable that actually matters is pH, not concentration.
What does over-feeding bog rosemary look like?
Brown, scorched leaf margins from too strong or too frequent a dose. White salt crust on the soil surface. Soft, lush growth that fruits or flowers poorly. Feeding bog rosemary an ordinary fertiliser, or growing it in hard tap water / limey soil, is the defining mistake — it triggers lime-induced chlorosis (yellow leaves, green veins) no amount of feeding fixes until the pH comes down.
Should I flush the soil of bog rosemary?
Flush bog rosemary with rainwater (not hard tap water, which raises pH) if salts build up; better still, mulch with pine needles or composted bark and water with rainwater to hold the acidity.
Keep reading
- Bog rosemary care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water bog rosemary — 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 callicarpa bodinieri var. giraldii 'profusion'
- How to fertilise callicarpa japonica
- How to fertilise callicarpa dichotoma
- All 8452 fertilising guides in the Growli library