Fertilising guide

How to fertilise Broad-Leaved Lavender (Lavandula latifolia)— schedule & NPK

Also called Broad-leaved lavender, Spike lavender, Portuguese lavender.

More about broad-leaved lavender

About Broad-Leaved Lavender

Lavandula latifolia · also called Broad-leaved lavender, Spike lavender · herb

A wild Mediterranean species closely related to English lavender but with noticeably broader, grey-green leaves and branched flowering stems bearing multiple flower spikes — a distinguishing feature from the single-stemmed English lavender. It is widely cultivated for its camphor-rich essential oil, which is produced in far greater quantity than from L. angustifolia, though with a coarser scent profile. Full sun and excellent drainage are the key requirements; it is moderately hardy and may need protection in colder parts of its USDA range. Lavender is toxic to cats, dogs, and horses according to the ASPCA.

Growth habit: Upright, bushy evergreen shrub with broader grey-green leaves and characteristically branched, multi-stemmed flower spikes.

What fertiliser broad-leaved lavender actually wants — and why

Broad-Leaved 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 broad-leaved 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 broad-leaved 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 broad-leaved lavender:

Light application of a balanced fertiliser in early spring only; this species thrives in lean conditions and over-feeding reduces aromatic oil content. 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 broad-leaved 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 broad-leaved lavender

Half strength is a sensible default for broad-leaved 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 broad-leaved lavender first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the broad-leaved lavender watering schedule.

Signs you are over-feeding broad-leaved lavender

Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for broad-leaved 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 broad-leaved 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 broad-leaved lavender care brief covers soil, humidity and the common problems for this species.

Flushing and leaching the salts

Pot-grown broad-leaved 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 broad-leaved 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 broad-leaved lavender — frequently asked questions

What fertiliser does broad-leaved 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. Broad-Leaved 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 broad-leaved lavender?

Light application of a balanced fertiliser in early spring only; this species thrives in lean conditions and over-feeding reduces aromatic oil content. Light application of a balanced fertiliser in early spring only; this species thrives in lean conditions and over-feeding reduces aromatic oil content. 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 broad-leaved lavender?