Celery needs a long growing season. Start the seeds indoors about 10–12 weeks before the expected last frost, from late February to early March. The seedlings can be transplanted outdoors once the risk of frost has passed and soil temperatures are above 10°C (50°F), generally from mid-May to mid-June in Quebec.

Celery prefers well-drained soil rich in organic matter, with a slightly acidic to neutral pH (6.0–7.0). Work compost into the soil before planting to improve its fertility and structure.

When transplanting, space the seedlings about 20–30 cm (8–12 inches) apart in rows at least 60 cm (2 feet) apart. This spacing promotes good air circulation and helps minimize disease problems.

Celery needs full sun to develop well but also tolerates partial shade. Make sure the plants receive at least six hours of direct sunlight each day.

It also needs evenly moist soil to develop properly. Water regularly to maintain soil moisture, especially during dry periods. Mulching around the plants can help retain moisture and prevent weeds.

Fertilize the celery plants with a balanced organic fertilizer about one month after planting. You can also add compost for continuous organic feeding.

Inspect the plants regularly for signs of pests or disease and act quickly to address any problems. Blanch the celery stalks by wrapping them in cardboard or newspaper, or tying them together with string, about two to three weeks before harvest to produce more tender, less bitter stalks.

Celery is generally ready to harvest about 100–120 days after transplanting, when the stalks are about 20–30 cm (8–12 inches) tall. To harvest celery, use a sharp knife to cut the stalks at the base of the plant, taking care not to damage the roots. You can harvest individual stalks as needed or harvest the whole plant by cutting all the stalks at once.