Fertilising guide

How to fertilise Lavender (Lavandula angustifolia)— schedule & NPK

Also called English lavender, true lavender, common lavender.

About Lavender

Lavandula angustifolia · also called English lavender, true lavender · flowering

Lavender is a Mediterranean evergreen subshrub grown for fragrant purple flower spikes and silvery foliage. English lavender (L. angustifolia) is the most cold-hardy; French and Spanish types are more tender. Sun and sharp drainage are non-negotiable. Pet-safe in typical garden quantities.

Lavandula angustifolia (English lavender) originates in the mountainous western Mediterranean (Pyrenees, French Alps); the 'English' name reflects cultivation, not origin.

Prefers poor, low-nutrient soil; supplemental feeding is generally unnecessary and reduces hardiness.

Growth habit: Woody evergreen subshrub

Watch for — No flowers: Insufficient sun or over-fertilising producing leaf at the expense of bloom.

Sources: rhs.org.uk, plants.ces.ncsu.edu, extension.colostate.edu

What fertiliser lavender actually wants — and why

Lavender flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.

Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency.

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 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 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 lavender:

Almost none; lean soil produces strong scent. A spring top-dress with compost is plenty. In practice: no routine feeding at all for lavender — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

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

None is the correct answer for lavender. The flower-versus-foliage trade-off is the whole point: hold back and you get the display.

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

Signs you are over-feeding lavender

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

Abundant leafy growth and very few flowers (the classic over-rich symptom).
Soft, floppy stems and a sprawling, leafy habit.
Scorched edges and salt crust if it has been fed in a container.

Signs you are under-feeding lavender

Effectively never an issue — these plants flower on poverty.
Only on genuinely dead soil: weak, thin growth and few blooms.
A short-lived plant in completely spent container compost.

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

Flushing and leaching the salts

If lavender has accidentally been fed and is all leaf, a plain-water flush plus a move to leaner soil resets it; otherwise no flushing is needed because you are not feeding it.

Organic vs synthetic feeds for lavender

Organic options

A thin compost mulch for soil structure is the absolute most; mostly, give it nothing. UK/US: leave it lean — no manure, no liquid feed. Poor soil is the active ingredient here.

Synthetic / liquid feeds

None. Synthetic feeds, particularly anything with appreciable nitrogen, directly suppress flowering in lavender.

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 lavender — frequently asked questions

What fertiliser does lavender need?

Little or nothing. Rich, especially nitrogen-rich, soil pushes foliage at the expense of flowers in this plant — lean ground is the technique, not a deficiency. Lavender flowers best on poor soil — feed it and you get a lush leafy plant with very few blooms, the exact opposite of what you want.

How often should I feed lavender?

Almost none; lean soil produces strong scent. A spring top-dress with compost is plenty. Almost none; lean soil produces strong scent. A spring top-dress with compost is plenty. In practice: no routine feeding at all for lavender — at most a thin compost mulch for soil structure, never a flowering or nitrogen feed.

What strength of feed for lavender?