Celery production is best in a cool (12 to 16 °C), humid and long growing season with an ample and uniform supply of moisture. It develops well on fertile, medium textured mineral soils with high organic matter under irrigation. Soil pH should be maintained in the range 6.0–6.8 (preferably above 6.5). Lower pH levels are tolerated on peat soils. Celery is a heavy feeder, requiring the application of large quantities of nutrients. Generally, ~66% of the nitrogen is applied at planting time and the remainder- side-dressed by 2-3 applications. Special care must be given to the Ca:N ratio, since "black-heart" syndrome (due to calcium deficiency) can be aggravated by excessive nitrogen fertilization. Sandy-loam soils may be low in potasium, so, applications of this nutrient should be done both as preplant and side-dressing.