Fertilising guide

How to fertilise Four-angled cassiope (Cassiope tetragona)— schedule & NPK

Also called Four-angled cassiope, Arctic white heather.

More about four-angled cassiope

About Four-angled cassiope

Cassiope tetragona · also called Four-angled cassiope, Arctic white heather · flowering

Four-angled cassiope is a compact arctic-alpine subshrub bearing tightly scale-like leaves arranged in four ranks along its stems, giving them a distinctive square cross-section. Solitary white bell-shaped flowers dangle from wiry red stalks in late spring. It thrives in cool, moist, acidic conditions and is suited to rock gardens in cold climates.

Growth habit: Low, mat-forming or cushion subshrub with erect, four-angled stems densely clothed in scale-like leaves

What fertiliser four-angled cassiope actually wants — and why

Four-angled cassiope 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.

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 four-angled cassiope: 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 four-angled cassiope, 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 four-angled cassiope:

Very light feeding only — a dilute half-strength ericaceous liquid fertilizer once in early spring is sufficient. Over-fertilizing disrupts its adaptation to nutrient-poor soils and can cause dieback. 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 four-angled cassiope 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 four-angled cassiope

Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for four-angled cassiope. The variable that actually matters is pH, not concentration.

Feeding always goes onto already-damp soil, never dry roots — water four-angled cassiope first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the four-angled cassiope watering schedule.

Signs you are over-feeding four-angled cassiope

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for four-angled cassiope:

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 four-angled cassiope

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 four-angled cassiope care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush four-angled cassiope 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 four-angled cassiope

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 four-angled cassiope — frequently asked questions

What fertiliser does four-angled cassiope 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. Four-angled cassiope 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 four-angled cassiope?

Very light feeding only — a dilute half-strength ericaceous liquid fertilizer once in early spring is sufficient. Over-fertilizing disrupts its adaptation to nutrient-poor soils and can cause dieback. Very light feeding only — a dilute half-strength ericaceous liquid fertilizer once in early spring is sufficient. Over-fertilizing disrupts its adaptation to nutrient-poor soils and can cause dieback. 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 four-angled cassiope?

What does over-feeding four-angled cassiope 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 four-angled cassiope 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 four-angled cassiope?