Fennel is a cool-season plant that grows best at temperatures between 15 and 20°C (60–70°F). Start the seeds indoors about four to six weeks before the expected last frost, from late March to early April. 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.

Fennel 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 fennel seedlings, space them about 30–45 cm (12–18 inches) apart in rows at least 60 cm (2 feet) apart. This spacing promotes good air circulation and helps minimize disease problems.

Fennel needs full sun to develop well, so make sure the plants receive at least six hours of direct sunlight each day.

It 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 fennel 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. Fennel can be susceptible to certain diseases, such as root rot and mould, which can be prevented by providing good air circulation and well-drained soil.

Fennel is generally ready to harvest about 90–115 days after planting, when the bulb reaches about 7.5–10 cm (3–4 inches) in diameter. To harvest fennel, use a sharp knife to cut the plant at the base of the bulb, taking care not to damage the roots. You can also harvest fennel leaves throughout the season by cutting the stems near the base of the plant.