What is the difference between tarragon and chervil?

Tarragon vs Chervil

The short answer

The two anise herbs of French cooking, and the same compound at two strengths. Both owe their character to estragole; tarragon carries far more of it and adds a faint bitterness, chervil is delicate and sweet and disappears under almost anything. They are unrelated plants — tarragon is an Artemisia in the daisy family, chervil an Apiaceae — which makes the shared note a coincidence of chemistry rather than of kinship. In fines herbes both are present, because the mixture wants the anise at two intensities rather than a double measure of either.

Side by side

Tarragon and Chervil compared side by side
	Tarragon	Chervil
Botanical identity	Artemisia dracunculus L.	Anthriscus cerefolium (L.) Hoffm.
Part used	leaf	leaf
Origin	Central Asia and southern Russia, with a native range extending across Siberia into western North America. The French cultivar is a European selection from that stock.	The Caucasus and western Asia, naturalised across much of Europe. Its spread into European gardens is old enough that it is often described as European, which is a naturalisation rather than an origin.
Flavour notes	anise, green, sweet, faintly bitter, grassy	delicate anise, green, sweet, fresh
Heat	Scoville does not apply	Scoville does not apply
Flavour	Sweet-anise and green at once, with a mild numbing tingle on the tongue that most cooks notice and few name — the same slight anaesthetic quality found in other estragole-rich plants. Russian tarragon has the green and almost none of the anise, which is why a dish made with it tastes vaguely of nothing in particular.	Delicate, faintly aniseed, slightly sweet, with a clean green finish and no bitterness or pungency at all. It is the mildest herb in this catalogue, which is both its character and the reason it is so easily lost — almost anything else on the plate will cover it.
Aroma	Anise, clearly, over a green grassy base with a faint bitterness behind it. The anise is not the sweet confectionery anise of aniseed but a sharper, more herbaceous version of it.	A light anise over a fresh green base, much gentler than tarragon and without its bitterness. The aroma is fugitive: it is at its clearest in the seconds after chopping and noticeably diminished a few minutes later.

Can you swap them?

Substitution is directional: the answer is often different in each direction, and both are recorded.

Chervil

Good match

Use: ~3× by volume — About three times the volume, because chervil carries far less estragole. Conventional rather than measured.

The same compound at a different concentration, which makes this an unusually clean substitution: both herbs owe their anise to estragole, and chervil is simply the quieter of the two. What is lost is force rather than character — a chervil version of a tarragon dish tastes correct and understated. What is gained is that chervil has none of tarragon’s faint bitterness.

How the replacement compares on each sensory axis
Flavour	Aroma	Colour	Heat
close	close	close	n/a

Works for

Egg dishes, where both belong anyway
Cream and butter sauces added off the heat
Anywhere the anise is wanted as an accent rather than a statement

Does not work for

Béarnaise, where tarragon is the named flavour and the quantity is large
Any dish cooked for more than a minute or two, since chervil is even less heat-tolerant
Most kitchens outside France, since chervil is harder to buy than tarragon

Established culinary practice

The substitution runs much better in this direction than in reverse: tarragon standing in for chervil overwhelms it.

Which should you buy?

Tarragon

Buy it fresh, or buy tarragon vinegar, or freeze it. Dried tarragon is the one dried herb in this catalogue that is hard to recommend for anything, because what drying removes is precisely the anise the herb is bought for. If a recipe calls for tarragon and only the dried jar is available, the honest options are to use tarragon vinegar in place of part of the liquid, or to accept that the dish will not taste of tarragon and season it some other way.

Chervil

Grow it or go without. Chervil is the clearest case in this catalogue of a herb that cannot be bought in any useful preserved form: the dried leaf has lost the anise entirely, freezing destroys the structure, and the fresh bunch keeps for two or three days. A pot on a shaded windowsill sown in succession is the only reliable supply, and it is the reason chervil is common in French home cooking and rare in British — not a difference of taste but of whether the plant is in the garden.

Full detail on tarragon and chervil, including evidence grades and sources for every claim above.