Oxymoron

An oxymoron is a figure of speech containing contradictory terms, the classic example being "military intelligence" but there is a whole website dedicated to examples of oxymorons and discussion forums to express your opinions on the terms.

When I was out for lunch at a garden centre I came across what I consider to be an oxymoron such as low maintenance gardening.

Actually this year the garden has actually looked good and I've not had to do much to it so it's probably a false oxymoron. Must trim some bushes tomorrow, they mushroomed since June.