Campanula medium reaches approximately 60–80 cm (24–31 in) in height. This biennial herbaceous plant forms rosettes of leaves in the first year, stems and flowers in the second one. The stem is erect, robust, reddish-brown and bristly hairy. The basal leaves are stalked and lanceolate to elliptical and 12–15 cm (5–6 in) long with serrated leaf edge. The upper leaves are smaller, lanceolate and sessile, almost embracing the stem.
The flowers are arranged in a racemoseinflorescence of extremely long-lasting blooms. These attractive bell-shaped flowers are short-stalked, large and hermaphroditic, with different shades of violet-blue or rarely white. The corolla has five fused petals with lightly bent lobes (known as a coronate flower type).