generally, lots of leaf but no bulb would mean too much nitrogen and not enough potassium. Nitrogen is used for leaf and stem growth, K is essential for fruit and flower formation. grow in soil that has had hungry plants like leafy greens of broccoli grown in it previously, and avoid high nitrogen manures, use well matured compost instead. The parent crops of modern cultivars of celery and celeriac grew in marshes, so make sure soil is deep and moisture holding. All through summer, it will be just leaves but the bulb will swell suddenly in a burst of metabolic resource direction in autumn/ early winter, in order to give itself food stores for the cold season. If temperatures are cool in your winter, you can leave in the ground unitl you need to harvest them.

- Amanda