Celery needs a long, warm growing season, and mature plants will stand in mild winters. It is best to start your own seeds indoors or buy starts from the nursery. For greatest success provide a steady supply of nutrients, water and well‐drained soil. The leaves, stems and seed can be enjoyed in a variety of dishes. Celeriac is a type of celery grown for its edible large root used to flavor soups.
Celery requires full sun, at least six hours of direct sun, with some shade during heat spells. Plant in rich, well drained soil. Plan for 2‐3 plants per person.
Start seeds indoors under lights 10‐11 weeks before desired planting time. In Portland, start seeds indoors mid February through May. Prepare planting area by mixing in 3‐4” of compost in the soil, and add granular all‐purpose fertilizer to each planting hole. Plant transplants when night temperatures are above 55°F in May and early June (plants will bolt if exposed to night temperatures below 55 for a week). Space plants 12” apart in rows 18‐24” apart. Cover new plantings with floating row cover to prevent carrot rust fly. To keep plants upright, work some soil up around them as they grow.
For whitened stalks, set bottomless milk carton, paper bag, or similar device over plants to exclude light from stalks (leaves must have sunlight). Or grow self‐blanching varieties.
Mulch celery beds with 1‐2” of compost to help retain moisture.
How much water your plants will require depends on the soil and weather. Celery loves water and is accustomed to drawing large amounts of water from boggy areas, so do not let it dry out. If plants dry out they may yield tough, stringy, dry stalks. Celery prefers drip, flood irrigation, or very good hand watering.
Celery is a heavy feeder, so fertilize every 3‐4 weeks with an all‐purpose granular or liquid fertilizer. Celery needs to grow quickly or it turns tough and bitter.
Most varieties will survive in the winter garden until spring. Mature plants are fine without frost protection down to the high teens. For continual summer and fall harvest, pick individual stalks as needed. If preferred, the entire bunch can be harvested at one time 100‐130 days after transplanting. Unopened flower buds and stems are also quite tasty. Celery stalks will turn limp soon after plucked from the garden. They can be refrigerated for up to a month or more, but are best left in the yard until ready to use. Wilted stalks can be refreshed by placing them in a tall glass of cold water.
Celeriac is harvested after light fall frost which improves it’s flavor. If you remove lower and lateral leaf shoots while celeriac is growing, you will end up with a nice smooth crown. Dig up the crown, rinse well and allow to dry. It can be kept in a cool, dry, dark place for up to a couple of months.
Other pests and diseases include: blackheart (a calcium deficiency), fusarium yellows (stunted yellow plants), mosaic virus (mottled leaves), loopers and armyworms (holes in leaves and green excrement among stalks), and tarnished plant bug (turns central leaves dark).