Fertilising guide

How to fertilise Moor Witch Purple Moor Grass (Molinia caerulea 'Moorhexe')— schedule & NPK

Also called Moor witch purple moor grass, Moorhexe purple moor grass, Purple moor grass.

More about moor witch purple moor grass

About Moor Witch Purple Moor Grass

Molinia caerulea 'Moorhexe' · also called Moor witch purple moor grass, Moorhexe purple moor grass · flowering

Molinia caerulea 'Moorhexe' (German: 'moor witch') is a compact, very upright cultivar of purple moor grass, native to the moorlands, bogs, and wet heathlands of Europe and western Asia. Unlike many ornamental grasses, it is a completely deciduous species that collapses and can be cleared away cleanly each winter, leaving no persistent dead thatch. It is prized for its stiffly erect, purple-tinted flowering stems that turn rich amber-yellow in autumn. The most important care point is to provide acid to neutral, reliably moist soil — it dislikes alkaline conditions. Molinia caerulea is not considered toxic to cats or dogs.

Growth habit: Fully deciduous, tightly upright clump-former with narrow basal foliage and extremely stiff, vertical flowering stems; one of the most compact Molinia cultivars at under 60 cm.

Watch for — Chlorosis on alkaline soils: Yellow, pale foliage indicates iron or manganese deficiency caused by high soil pH; apply a chelated iron feed (sequestered iron) and acidify the soil with sulphur chips or ericaceous mulch.

What fertiliser moor witch purple moor grass actually wants — and why

Moor Witch Purple Moor Grass 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 moor witch purple moor grass: 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 moor witch purple moor grass, 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 moor witch purple moor grass:

Apply a low-phosphorus, ericaceous or balanced fertiliser (avoiding lime-containing products) in early spring; feeding is rarely required in naturally fertile or peaty soils. 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 moor witch purple moor grass 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 moor witch purple moor grass

Follow the ericaceous product's own rate — these are formulated for the plant, so the dilution on the label is right for moor witch purple moor grass. The variable that actually matters is pH, not concentration.

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

Signs you are over-feeding moor witch purple moor grass

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for moor witch purple moor grass:

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 moor witch purple moor grass

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 moor witch purple moor grass care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Flush moor witch purple moor grass 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 moor witch purple moor grass

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 moor witch purple moor grass — frequently asked questions

What fertiliser does moor witch purple moor grass 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. Moor Witch Purple Moor Grass 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 moor witch purple moor grass?

Apply a low-phosphorus, ericaceous or balanced fertiliser (avoiding lime-containing products) in early spring; feeding is rarely required in naturally fertile or peaty soils. Apply a low-phosphorus, ericaceous or balanced fertiliser (avoiding lime-containing products) in early spring; feeding is rarely required in naturally fertile or peaty soils. 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 moor witch purple moor grass?

What does over-feeding moor witch purple moor grass 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 moor witch purple moor grass 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 moor witch purple moor grass?