Candytuft is a mid-spring bloomer that some have described as resembling a snowbank.  Blooms are profuse and completely cover the mounding plants.  Leaves are narrow, almost needle like, about an inch long and are evergreen.  Though the plants become a bit ragged as winter progresses, this is made up for by the long lasting bloom period. 

Candytuft, Iberis sempervirens: With a low slowly spreading mounding habit that hangs quite nicely, candytuft is a good "top of the wall" selection.

Iberis is an old classic perennial, having been used for centuries.  In spite of its spartan appearance, there should be a place for it in most gardens.  Give it well drained, average soil, though it will tolerate droughty conditions.  Cut it back hard about every two years to prevent it from getting leggy.

While there are some named cultivars such as 'Autumn Snow', 'Little Gem', and 'Purity', there seems to be liutlle difference between them other than maybe height. 

Candytuft, Iberis sempervirens: This closeup of Candy tuft reveals delicate individual infloresences.