Celery stalk should be sown under shelter (temp lower to 15°C) in March-April. As soon as the celery has 2 or 3 leaves, it needs to be transplanted for 6 weeks in individual pocket, before planting out. It is important to tie the leaves together to blanch them and to ensure that the sides are tender and less bitter. The blooming period occurs in the second year (between June and September); it will give white, yellow or greenish flowers gathered in umbrella-shaped clusters (flowers that are all around the stems all starting from the same point on the stem). Harvesting takes place from July to October in the first year.
Like other vegetables, celery is affected by diseases including septoria (a fungus that will cause black spots to appear on the leaves and will eventually contaminate the sides). Subsequently this disease causes a slower growth of the plant, which can even lead to the death of the latter. Celery stalk is a vegetable but also a leaf.