Root Celery, Celeriac is a delicious vegetable commonly used in Europe in place of our stalk celery. The root is used in soups and stews. A delicious salad is made from the cooked, diced or cubed root with diced onion and a little mayonnaise. The big white root has few external markings and grows vigorously. Flavor hovers between a mild celery and parsley and it has the consistency of a potato. Celeriac is surprisingly versatile and makes a fantastic puree that matches well with other root vegetables. 100 days.