Fertilising guide

How to fertilise Cotton Lavender (Santolina chamaecyparissus)— schedule & NPK

Also called Cotton Lavender, Lavender Cotton, Santolina.

More about cotton lavender

About Cotton Lavender

Santolina chamaecyparissus · also called Cotton Lavender, Lavender Cotton · herb

Santolina chamaecyparissus is a compact, aromatic, evergreen subshrub native to rocky, dry terrain across the western and central Mediterranean basin, including Spain, France, Italy, and North Africa. It is prized for its finely divided, silver-grey, intensely fragrant foliage and cheerful, bright yellow, button-like flowerheads borne on erect stems in midsummer. The single most important care fact is that it must have sharply drained, lean soil in full sun; rich or wet soil causes the plant to become floppy, woody at the centre, and prone to root rot. Santolina is not listed by the ASPCA on its toxic plant lists, but the essential oil contains linalool and camphor which may be irritating to pets in large quantities; treat as mildly-toxic.

Growth habit: Dense, rounded, evergreen subshrub with finely divided, silver-grey, aromatic foliage.

Watch for — Root rot in wet or clay soil: Wet winters or poorly drained soil rapidly cause root and crown decay, especially in cold weather. Plant in raised beds or on slopes with added grit, and avoid autumn fertilisation.

What fertiliser cotton lavender actually wants — and why

Cotton Lavender is a soft, fast leafy herb that you harvest hard — a modest balanced feed keeps tender growth coming without tipping it into bland or bolting.

A balanced general feed (even N-P-K) at modest strength — enough nitrogen to keep replacing the leaves you pick, but not so much that flavour thins or it bolts to seed.

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 cotton lavender: 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 cotton lavender, 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 cotton lavender:

Feed sparingly with a low-nitrogen slow-release granule in spring only; regular feeding or rich soil reduces hardiness and compactness. In practice: a balanced liquid feed every few weeks through the main growing and harvesting season (spring through early autumn), more often the harder you are picking it.

The dormant-season rule matters more than the exact interval: skip feeding entirely when cotton lavender 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 cotton lavender

Half strength is a sensible default for cotton lavender — enough to fuel regrowth after cutting, gentle enough that the leaves stay aromatic rather than watery.

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

Signs you are over-feeding cotton lavender

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

Fast, soft, pale growth with diluted, less aromatic flavour.
Early bolting (running to flower) and a bitter edge.
Salt crust and scorched tips on container plants.

Signs you are under-feeding cotton lavender

Pale, slow regrowth after cutting and small leaves.
A tired, stalled plant that cannot keep up with harvesting.
Yellowing older leaves in a long-spent pot.

If the symptoms point at watering, light or roots rather than nutrition, the full cotton lavender care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Pot-grown cotton lavender builds up feed salts quickly — water until it drains each time and flush the pot with plain water every few weeks, especially on a sunny windowsill.

Organic vs synthetic feeds for cotton lavender

Organic options

A diluted seaweed feed or worm-casting tea keeps soft growth coming without overdoing it. UK: dilute seaweed or Westland; US: Espoma Garden-tone or Neptune's Harvest. Gentle, hard to overdo, flavour-friendly.

Synthetic / liquid feeds

A balanced liquid feed at half strength through harvesting — UK: Phostrogen, Baby Bio or Westland; US: Miracle-Gro all-purpose at half strength. Fast regrowth; just do not overdo the nitrogen.

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 cotton lavender — frequently asked questions

What fertiliser does cotton lavender need?

A balanced general feed (even N-P-K) at modest strength — enough nitrogen to keep replacing the leaves you pick, but not so much that flavour thins or it bolts to seed. Cotton Lavender is a soft, fast leafy herb that you harvest hard — a modest balanced feed keeps tender growth coming without tipping it into bland or bolting.

How often should I feed cotton lavender?

Feed sparingly with a low-nitrogen slow-release granule in spring only; regular feeding or rich soil reduces hardiness and compactness. Feed sparingly with a low-nitrogen slow-release granule in spring only; regular feeding or rich soil reduces hardiness and compactness. In practice: a balanced liquid feed every few weeks through the main growing and harvesting season (spring through early autumn), more often the harder you are picking it.

What strength of feed for cotton lavender?