Fertilising guide

How to fertilise Winter Tarragon (Tagetes filifolia)— schedule & NPK

Also called Irish Lace Marigold, Filigree Marigold.

More about winter tarragon

About Winter Tarragon

Tagetes filifolia · also called Irish Lace Marigold, Filigree Marigold · herb

Tagetes filifolia, sold as winter tarragon or Irish lace, is a tender marigold relative from Mexico and Central America. It forms a mound of finely divided, thread-like bright green foliage that smells of anise and licorice, used as a tarragon substitute. Tiny pale flowers appear in autumn. It needs warmth and full sun to thrive.

Growth habit: Tender bushy annual or short-lived perennial forming a rounded, feathery mound; an autumn short-day bloomer.

What fertiliser winter tarragon actually wants — and why

Winter Tarragon is a lean, aromatic herb — the essential-oil flavour you grow it for is strongest in poor soil, so feeding it actively makes it worse.

Little or nothing. If anything, a very weak balanced feed or a thin compost top-dress — never a rich nitrogen feed, which dilutes the aromatic oils and produces soft, bland, floppy growth.

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 winter tarragon: 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 winter tarragon, 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 winter tarragon:

Feed sparingly. A balanced liquid feed at half strength every 3-4 weeks in the growing season is plenty. Like most marigolds, rich nitrogen gives lush leaves but fewer flowers and weaker scent. In practice: a spring compost top-dress at most, and otherwise leave winter tarragon unfed — lean, sharp-draining soil is exactly what concentrates its flavour.

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

As weak as it gets for winter tarragon, or none at all. The flavour-versus-growth trade-off runs the opposite way to leafy crops: restraint is the technique.

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

Signs you are over-feeding winter tarragon

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

Lush, soft, fast growth with noticeably weaker scent and flavour.
Floppy stems, sparse essential oils, and poor cold/wet hardiness.
Salt crust in containers and scorched leaf tips from over-feeding.

Signs you are under-feeding winter tarragon

Rare — these herbs thrive on lean soil.
Only on truly exhausted soil: pale, thin, very slow growth.
A short-lived, weak plant in a long-spent container.

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

Flushing and leaching the salts

Over-feeding is so unlikely with winter tarragon that flushing is rarely needed; if a container has had feed, a single plain-water flush and a switch to a leaner, grittier mix resets it.

Organic vs synthetic feeds for winter tarragon

Organic options

A thin spring mulch of garden compost or leaf-mould is the most these want. UK: a little garden compost; US: a light Espoma Garden-tone top-dress at most. Lean and gritty beats fed and rich every time.

Synthetic / liquid feeds

Generally none for winter tarragon. At absolute most, a very dilute balanced feed once or twice in a container; in the ground, nothing — synthetic feeds work directly against the flavour.

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 winter tarragon — frequently asked questions

What fertiliser does winter tarragon need?

Little or nothing. If anything, a very weak balanced feed or a thin compost top-dress — never a rich nitrogen feed, which dilutes the aromatic oils and produces soft, bland, floppy growth. Winter Tarragon is a lean, aromatic herb — the essential-oil flavour you grow it for is strongest in poor soil, so feeding it actively makes it worse.

How often should I feed winter tarragon?

Feed sparingly. A balanced liquid feed at half strength every 3-4 weeks in the growing season is plenty. Like most marigolds, rich nitrogen gives lush leaves but fewer flowers and weaker scent. Feed sparingly. A balanced liquid feed at half strength every 3-4 weeks in the growing season is plenty. Like most marigolds, rich nitrogen gives lush leaves but fewer flowers and weaker scent. In practice: a spring compost top-dress at most, and otherwise leave winter tarragon unfed — lean, sharp-draining soil is exactly what concentrates its flavour.

What strength of feed for winter tarragon?