Celery should be harvested once plants reach a marketable size, but before the internal tissues become spongy or pithy. Pithiness is increased by pre-harvest stresses such as uneven irrigation, cold temperatures, or flower induction.
Celery is around 95% water. Rapid cooling after harvest is essential to keep it crisp. Hydro-vacuum cooling is an energy efficient and fast way to cool celery. Hydrocooling is also essential. While storage life is greatest at close to 0ºC, celery is very susceptible to freezing. Storage at 2°C can provide a margin of safety without compromising quality.