Celery

Celery, Apium graveolens, is an aromatic biennial plant in the family Apicaceae grown primarily for its stalk and taproot which are used as vegetables. The rhombic leaves of the celery plant grow in a rosette and are 3–6 cm (1.2–2.4 in) long and 2–4 cm (0.8–1.6 in) broad on a branched central stem which is highly ribbed. The plant produces creamy white flowers in dense umbels (an umbrella of short flower stalks) and produces broad oval seeds 1.5–2 mm (<0.1 in) long and wide. Celery is a biennial plant that is commonly grown as an annual and it can reach a height of about 1 m. Celery may also be referred to as celeriac which is the name given to the root and is believed to have originated in the Eastern Mediterranean.


Celery is eaten around the world as a vegetable. Both the taproot and leaves are often used. Temperate countries grow celery for its seeds, which are often mixed with salt to make celery salt for seasoning.


Basic requirements Celery is a cool season vegetable which grows best in cool climates in well-draining, fertile soils with a pH between 6.0 and 6.8.. Celery plants grow optimally in cool, moist locations and will tolerate some shade but will not tolerate heat. The plants require constant moisture and can tolerate temperatures between 5 and 27°C (41–80.6°F) with the optimum for growth being between 15–21°C (59–69.8°F). If temperatures drop below 12.7°C (55°F) then the plants will benefit from protective coverings to prevent the plants from bolting (going to seed). Sowing seeds For best results celery should usually be started indoors or in a glasshouse and transplanted to the garden or field. Germination of celery seeds is slow and the seeds should be planted 10 to 12 weeks before the last Spring frost. Soaking seeds in warm water overnight prior to planting can increase germination success. Plant seeds in seedling flats containing a good quality sterile seed starting mix by lately sprinkling a pinch of seeds across the soil surface and covering with a thin layer of starting mix or vermiculite. Place trays in a warm location inside the house or in the glasshouse and keep well-watered. Do not allow the trays to dry out. It is important to keep the soil at the temperature between 12.7 and 21°C (55 and 70°F). The optimum temperature for germination is 60° to 70° (15° to 21° C) and the seedlings should emerge within 2–3 weeks. The seedlings can be potted into individual pots when the are about 5 cm (2 in) tall. Transplanting Seedlings are ready to transplant when they are 15 cm (6 in) tall and have been hardened off. Prepare the transplant site in advance of planting by working fertilizer or compost into the soil and plant the seedlings when the weather has settled after the last frost. Seedling should be planted at the same depth as their previous container and should be spaced 15–20 cm (6–8 in) apart in rows spaced 60–90 cm (2–3 ft) apart. General care and maintenance Celery is a very heavy feeder and should be fed every 10–14 days with a balanced fertilizer. The plants require constant moisture and should be provided with at least 1 inch of water per week. A layer of mulch spread around the plants helps to conserve the moisture in the soil and prevents weeds. Any weeds should be gently removed from around the plants. If temperatures are forecast to drop below 12.7°C (55°F) then the plants should be protected with cloches to prevent them developing weak stalks. Prolonged exposure to temperatures below this threshold will result in bolting. Blanching Blanching is the act of deliberately covering plant parts to prevent photosynthesis, thus keeping the parts pale in color. Many people choose to blanch celery stalks to prevent them becoming bitter. Self-blanching varieties are also available. To blanch celery, the soil can simply be mounded around the stalks to just below the leaves. This can be done gradually as the plants grow, or about two weeks prior to harvest. Alternatively, newspaper or cardboard can be tied around the stalks or boards can be erected around the plants to block out sunlight. Harvesting Celery can begin to be harvested when the stalks are about 20 cm (8 in) tall. Unblanched celery can be harvested as needed by cutting stalks from the outside in. Blanched celery can be harvested by cutting the plant just below the soil line. The plants can be kept in the garden until Fall and will tolerate a light frost but not continuous heavy frosts. If uncovered, the stalks will grow darker in color and the resultant texture will be more fibrous than the young stalks.


CABI Crop Protection Compendium. (2008). Apium graveolens datasheet. Available at: http://www.cabi.org/cpc/datasheet/6599. [Accessed 10 November 14]. Paid subscription required. Davis, R. M. & Raid, R. M. (2002). Compendium of Umbelliferous Crop Diseases. American Phytopathological Society Press. Available at: http://www.apsnet.org/apsstore/shopapspress/Pages/42872.aspx. Available for purchase from APS Press. Stephens, J. M. (2009). Celeriac — Apium graveolens L. var.rapaceum (Mill.) Gaud. Beaup. University of Florida IFAS Extension. Available at: http://edis.ifas.ufl.edu/pdffiles/MV/MV04300.pdf. [Accessed 10 November 14]. Free to access. West, B. & Drost, D. (2010). Celery in the Garden. Utah State University Cooperative Extension. Available at: https://extension.usu.edu/files/publications/publication/HG_Garden_2006-03.pdf. [Accessed 10 November 14]. Free to access.