There are two main types: green-ribbed with large green leaves, and blanched white with white ribs and yellow leaves. Celery is available all year round. When buying, choose crisp stalks. Whole heads should have plenty of small inner stalks and ‘heart’. Avoid over-large heads as they may be stringy. Celery’s crisp and tangy flavour makes it useful in salads, sandwiches and dips.