Fertilising guide
How to fertilise Heather (Calluna vulgaris)— schedule & NPK
Also called Heather, Ling, Scots Heather.
More about heather
About Heather
Calluna vulgaris · also called Heather, Ling · flowering
Calluna vulgaris is a hardy, acid-loving moorland shrub prized for its late-summer to autumn blooms in shades of pink, purple, and white. Thriving in full sun and free-draining ericaceous soil, it is one of the toughest flowering shrubs for UK and northern US gardens, tolerating frost, wind, and drought once established.
Growth habit: Low-growing, spreading, evergreen shrub
Watch for — Soil pH too high (chlorosis): Yellowing foliage with green veins indicates iron deficiency caused by alkaline soil. Apply sulphur dust to lower pH, switch to rainwater irrigation, and treat with sequestered iron chelate feed.
What fertiliser heather actually wants — and why
Heather 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 heather: 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 heather, 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 heather:
Feed sparingly once a year in early spring with a specialist ericaceous fertiliser (e.g. sulphate of ammonia or proprietary azalea feed). Heavy feeding produces soft, weak growth. Container plants benefit from a half-strength liquid ericaceous feed monthly from April to August. 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 heather 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 heather
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for heather. The variable that actually matters is pH, not concentration.
Feeding always goes onto already-damp soil, never dry roots — water heather first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the heather watering schedule.
Signs you are over-feeding heather
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for heather:
- 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 heather
- 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 heather care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush heather 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 heather
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 heather — frequently asked questions
What fertiliser does heather 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. Heather 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 heather?
Feed sparingly once a year in early spring with a specialist ericaceous fertiliser (e.g. sulphate of ammonia or proprietary azalea feed). Heavy feeding produces soft, weak growth. Container plants benefit from a half-strength liquid ericaceous feed monthly from April to August. Feed sparingly once a year in early spring with a specialist ericaceous fertiliser (e.g. sulphate of ammonia or proprietary azalea feed). Heavy feeding produces soft, weak growth. Container plants benefit from a half-strength liquid ericaceous feed monthly from April to August. 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 heather?
Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for heather. The variable that actually matters is pH, not concentration.
What does over-feeding heather 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 heather 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 heather?
Flush heather 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
- Heather care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water heather — 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 bougainvillea 'san diego red'
- How to fertilise bougainvillea 'raspberry ice'
- How to fertilise persian violet
- All 8452 fertilising guides in the Growli library