The celery (Apium graveolens L.) is a biennial plant belonging to the Celeriaceae family. There are three varieties of cultivated celery: turnip-rooted (celeriac), salad and cutting celery.
Celery is a cold-tolerant plant capable of withstanding autumn frosts of 7-9°C below zero. Young celery plants tolerate temperature drops down to 3-6°C below zero. The celery roots cannot withstand subzero temperatures and, therefore, should be harvested before the onset of frosts. The optimum growth temperature is 12-15°C. Germination occurs at 2-3°C; the optimum germination temperature is 20-22°C.
Celery is a moisture-loving and light-demanding plant. For normal growth, celery plants require an adequate soil moisture content: 75-80% of field moister capacity early in the growing season and 70-75% of field moister capacity a month before harvesting.
Growing tips
Having a long growing period and very small, slow-germinating seeds, celery is cultivated by transplanting. Prior to emergence, temperatures are maintained in the range of 20-25°C. Upon seedling emergence, the temperature is lowered to 14-16°C. The optimum temperature for seedling growth is 18-22°C. Prolonged overchilling of young celery plants (exposure to temperatures lower than 10°C) may lead to bolting.
At transplanting, the seedlings should be 60-65 days old and have 5-6 true leaves.
The planting pattern at a regular (habitual) planting site in the open ground is 50 x 30-50 cm. The plant density is 4-8 pl/m2 (40,000-80,000 pl/ha). The seeding rate is 0,1-0,2 g per 10 m2 of open ground.
Celery has high soil moisture and nutrient demands. Organic fertilizers are applied at a rate of 40-50 kg per 10 m2 (40-50 ton/ha) and mineral fertilizers at a rate of 450 g ammonium nitrate, 750 g superphosphate and 300-400 g potassium salt per 10 m2 (NPK 150 kg of active substance each per hectare).
During the growing season, celery plants are given 8-10 irrigations with the water application rate of 350-450 l per 10 m2 (350-450 m3/ha).
In growing salad celery, it is good practice to ridge up the plants where the production of light-colored, tender, bitter-free leafstalks is desirable. The quality of blanched leafstalks is higher if the stalks of each plant are wrapped in dark (light-proof) paper or other material, rather than being hilled-up.
The celery roots keep well in cellars, pits and storage piles if interlaid with wet sand or earth.