Ilam is named for Ilam Hall in Staffordshire, England, the birthplace of John Watts-Russell (1826-1875). He came to Canterbury in 1850 on the Sir George Seymour, one of the first four immigrant ships of the Canterbury Association. A wealthy man, he purchased 500 acres at Riccarton for three pounds per acre. He named it Ilam and built a sod hut.
In 1858 Watts-Russell returned from a visit to Britain with 20,000 bricks, which he used to build the lower storey of a two storey house. Watts-Russell sold Ilam in 1866 and is buried in the upper Riccarton Church graveyard. Later owners of Ilam included Leonard Harper, "Ready-money" Robinson, Patrick Campbell and G D Greenwood.
Ilam Homestead burnt down in 1911 and was rebuilt by Edgar Stead. He established the wonderful azalea and rhododendron gardens. When he sold Ilam to Canterbury College he requested that the gardens be maintained in perpetuity.