Cultivar selected from Heuchera sanguinea, a perennial from the Saxifragaceae family whose type species is native to the southwestern United States and northern Mexico, where it grows in shaded rocky canyons, moist cliffs, and wooded slopes, generally between 1,500 and 2,500 meters in altitude.
The 'Firefly' cultivar forms a dense and regular basal clump, 20 to 30 cm in foliage height, with heart-shaped, lobed leaves slightly marbled with silvery gray on a medium green background, a trait inherited from the type species. The petioles and flower stems are finely hairy and tinged with dark red.
The flowers, tubular and bright, are an intense scarlet red, grouped in loose and elegant clusters carried by slender and upright stems of 40 to 55 cm. This particularly saturated hue, close to vermilion, fully justifies the name of the cultivar and regularly attracts hummingbirds in its native area.
In its natural habitat, the species blooms from May to August. In cultivation, 'Firefly' blooms from May to July, with sometimes a resurgence at the end of summer if the stems are removed after the first flowering. It requires a cool, well-drained, and humus-rich soil, in partial shade or gentle sun; it tolerates moderate drought better than many other garden Heuchera.