Fertilising guide
How to fertilise Jagged Lavender (Lavandula pinnata)— schedule & NPK
Also called Jagged lavender, Fern leaf lavender, Pinnate lavender.
More about jagged lavender
About Jagged Lavender
Lavandula pinnata · also called Jagged lavender, Fern leaf lavender · tropical
A frost-tender lavender native to the Canary Islands and Madeira, grown for its striking, deeply pinnately lobed silver-grey leaves and airy spikes of pale violet-blue flowers produced over a long season. It thrives in dry, sunny conditions with sharply drained soil and is suitable for outdoor cultivation only in essentially frost-free climates; elsewhere it performs well as a container plant overwintered under glass. The delicate, feathery foliage distinguishes it immediately from other lavenders. Lavender is toxic to cats, dogs, and horses according to the ASPCA.
Growth habit: Open, upright evergreen subshrub with deeply pinnately divided, silver-grey aromatic leaves and slender, multi-branched flowering stems.
What fertiliser jagged lavender actually wants — and why
Jagged Lavender is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
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 jagged 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 jagged 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 jagged lavender:
Feed monthly with a dilute, balanced liquid fertiliser from spring through early autumn; cease feeding entirely when overwintering under glass in cool conditions. Treat that as monthly between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when jagged 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 jagged lavender
Half strength is the safe default for jagged lavender — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water jagged lavender first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the jagged lavender watering schedule.
Signs you are over-feeding jagged lavender
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for jagged lavender:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding jagged lavender
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full jagged lavender care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of jagged lavender with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for jagged lavender
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
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 jagged lavender — frequently asked questions
What fertiliser does jagged lavender need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Jagged Lavender is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed jagged lavender?
Feed monthly with a dilute, balanced liquid fertiliser from spring through early autumn; cease feeding entirely when overwintering under glass in cool conditions. Feed monthly with a dilute, balanced liquid fertiliser from spring through early autumn; cease feeding entirely when overwintering under glass in cool conditions. Treat that as monthly between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for jagged lavender?
Half strength is the safe default for jagged lavender — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding jagged lavender look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding jagged lavender year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of jagged lavender?
Flush the pot of jagged lavender with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Jagged Lavender care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water jagged lavender — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
- How to fertilise ruellia devosiana
- How to fertilise porphyrocoma pohliana
- How to fertilise justicia scheidweileri
- All 10153 fertilising guides in the Growli library