Chervil

Light and exposure

Chervil is one of the few herbs that hates full sun. A spot that is too hot and too bright sends it into flower within a few weeks, before you have even had a chance to enjoy it. Set it in partial shade: at the foot of a wall that stays in shade, under a light shrub, in the shade cast by taller plants in the vegetable garden, or on a windowsill that does not catch the midday sun.

On either side of summer, when the sun stays gentle, it tolerates a brighter position without trouble. It is in high summer that you really have to protect it: sown in light shade at the heart of the warm season, it lasts far longer than in a scorching spot. Think of partial shade as the default setting, not as a fallback.

Watering

Cool soil is the key for chervil. Ground that dries out means guaranteed bolting and foliage that turns leathery. Water regularly to keep the soil moist without excess, especially in dry, windy weather, and mulch the base to hold moisture longer.

In a pot, keep a close eye: the compost dries fast and a thirsty chervil flowers at once. A morning watering, at the base, suits it well. In an often humid climate, watering becomes mainly an issue during the dry spells of high summer; the rest of the year, the rain does a good part of the work.

Soil and repotting

Chervil is happy in light, cool, humus rich soil, the kind that holds moisture without turning to mud. Ordinary garden soil, lightened with a little mature compost, is plenty. It has no great demands, it is above all coolness that matters more than richness.

Avoid soils that crust over on the surface and prevent the small seeds from emerging. A light raking before sowing and a veil of fine compost on top help you get even germination. In a pot, ordinary compost mixed with a little compost does the job perfectly, as long as it does not dry out between two waterings.

Temperature and humidity

Chervil is hardy and stands the cold well: it comes through cold winters without trouble and even self seeds from one year to the next. It is the autumn seedlings that, under a cold frame or fleece, can hold for a good part of winter and provide leaves during the bad season.

Its real enemy is heat. Beyond 22 or 25 degrees, combined with drought, the plant runs to flower and stops producing tender foliage. That is why summer sowings are reserved for cool, shaded corners. Chervil is therefore more a herb of the mild seasons than of the heart of summer.

Pruning and upkeep

You do not prune chervil in the strict sense, you harvest it. Cut the most developed outer leaves at the base, leaving the heart to produce new shoots. Regular harvesting keeps the plant full and delays flowering a little. Pick in the morning rather, when the foliage is full of freshness and most fragrant.

Remove the flower stems as soon as they appear if you want to prolong the leaf harvest; flowering marks the end of the cycle for that clump. Mind one point of vigilance that is anything but trivial: never harvest an unidentified wild plant believing it to be chervil. When young, several toxic wild umbellifers resemble it closely, and only sure identification allows picking.

Pests and diseases

Chervil is little prone to disease. Its main trouble in a humid climate is powdery mildew or a light felting on the foliage when the plants are too crowded and the air stagnant. Thin the sowings to let the air circulate, and avoid watering onto the leaves at the end of the day.

Slugs and snails enjoy the tender young shoots, especially in a wet spring: watch the emerging seedlings and protect them if needed. Aphids can also settle in during dry weather. Nothing serious as a rule: a well placed chervil, in the cool and not too dense, gets through the season without real problems.

Propagation

Chervil is sown, and only in place: it withstands transplanting badly, which breaks its young root and often triggers premature bolting. Sow directly in the open ground or in the final pot, broadcast or in rows, then barely cover and keep moist until emergence, which takes one to two weeks. Then thin to leave a few centimetres between the plants.

The secret of a continuous harvest is staggered sowing: repeat a small handful every two to three weeks from March to September, choosing more shaded spots as the summer heats up. One imperative safety point: use only seed bought or harvested from your own safe plants. Cultivated chervil is edible and harmless, but mistaking a self sown seedling for a toxic wild umbellifer such as fool’s parsley would be a mistake never to make. When in doubt about a plant that came up on its own, you do not eat it.

Month-by-month care calendar

Green Hub tips

• Always sow in place and in small staggered handfuls: chervil hates transplanting and runs to seed if you disturb it.
• In summer, put it in partial shade and keep the soil cool. In full sun and dry, it runs to flower before it is good to harvest.
• Use only safe seed and never harvest a plant that came up on its own without certainty: when young, chervil resembles toxic umbellifers.
• Let one or two plants seed at the end of the season: chervil self seeds on its own and starts again in the cool corners the following year.