Michigan State University Extension
Preserving Food Safely - 01600021
Storage can be done in several ways. Late celery may be stored in the garden for 1 to 2 months by building up soil at the base of the plant. Gradually build up the bank of soil to the top of the plant. This should be done before winter sets in. As the weather gets colder, cover the plants with straw held down by boards.
Celery may also be dug out of the garden, with the roots still attached, and placed in the basement or root cellar before freezing temperatures occur. Set the plants on the floor and pack them together tightly. If kept moderately moist, the plants will keep 1 to 2 months.
A third method of storage would be to place the plants in a trench. The trench should be 10 to 12 inches wide and 24 inches deep. Again, dig out the plants leaving the soil attached, pack the celery closely into the trench, and then water. Allow the plant tops to dry off. Make a sloping roof for the trench and cover it with straw adding more straw as the weather gets colder. Celery will keep in this storage until late winter.
Celery should not be stored with turnips or cabbage as the flavor of the celery will be tainted. The temperature of the storage area should be near 32 degrees Fahrenheit and the humidity moderate. The roots should be in moist sand or soil.