They prefer an acid one so use ericaceous compost.

Hi, welcome to GoY, Camellia's need an acid soil, ph 5.5-6.5, humus rich, moist but well drained, plant in a position where they don't get early morning sun, and not too deep, the top of the root ball should just be level with the firmed soil, and ideally they should have a good mulch every spring, Derek.

Acidic to neutral not alkaline... Make sure any Camellia you plant won't get early morning sun as this is what causes the flower bods to drop if the get frost on them.

They seem happy round here with very slightly acid soil, pH6.5.