Celery (Apium graveolens): surface sowing, growing and harvest

Celery (Apium graveolens) is a marathon vegetable: a very long growing season, seeds that need light to germinate, and a permanent thirst inherited from its marshland origins. It is a classic of the February–March indoor sowing.

When and how to sow celery?

• Long season required: start seeds indoors at least 8–10 weeks before your region's last frost date, at a gentle 10–15 °C.
• In practice: sow under cover in early spring in a seed tray, at about 15 °C, keeping the compost moist; germination can take up to three weeks.
• Do not cover the seeds: they need light to germinate. Sow them on the surface of damp compost and just firm lightly.
• For continuity, sow every 3 weeks from late February to early June.
• In cold regions, sow under a cold frame in winter; where winters are mild, you can wait until midsummer.

Surface-sown seeds, gentle constant warmth (15 °C), a substrate that never dries: that is precisely the spec of a germination kit — the heating mat holds the temperature, and the LED lamp supplies the light celery seeds demand to sprout.

Planting: the richest soil in the garden

• Celery demands the richest soil and permanent water — it is a marshland plant in the wild.
• Soil: rich, loamy, liberally amended with well-rotted compost, pH between 6.5 and 7.0; a spongy earth that holds moisture without going boggy.
• Exposure: full sun preferred, but it tolerates light shade.
• Spacing: 25 cm between plants is standard; top yields come at 27 × 27 cm.

Watering: non-negotiable

Keep celery moist throughout the growing season — in the wild it is a marsh plant. The stakes are also culinary: a thirsty celery produces fibrous, bitter stalks. Regular watering is not a detail.

Harvest

• After about 3 months, start harvesting either by pulling the whole plant or by taking only the outer stalks as needed.
• For blanched varieties, cut the celery at the collar for immediate use: this etiolation does not allow long storage.

In the kitchen

Garden-grown celery stalks, not artificially blanched, have a more powerful flavour and better nutritional value than shop-bought — an unbeatable home argument.

A bit of history

• Celery originates from Asia and Europe, where it grows naturally in marshy ground.
• It was an important plant in Ancient Greece, associated with the cult of the dead — and winner's wreaths at the Isthmian Games were woven from it.
• The town of Kalamazoo, Michigan, was once nicknamed "Celeryville" for its production.

Precautions

Diseased or browned stems should not be eaten. A note for seeds (not stalks): the use of celery "fruits" is contra-indicated during pregnancy — which has nothing to do with ordinary stalk consumption.

Going further: celery rewards careful sowing — start yours in February with the complete kit with greenhouse + LED + mat. And for the month's right jobs, sign up for the newsletter in the footer.

Growing calendar

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Sowing
Planting
Harvest