Farmers of cold sensitive fruit will usually simply mist their field/orchards with water and the resulting coating of ice insulates the fruits from the damaging effects of frost.
We had a heavy frost in Sept. a few years ago....a friend misted some of his plants and they ended up molding. We threw away more than we kept. So that method seems to have some drawbacks. Perhaps he misted too heavily?
Could you cover the ground around the plant with a thick layer of grass clippings?