What is the proper adjective of orchids?

The plural noun is orchids and the singular noun is orchid; the adjective is also spelled orchid. Example use as an adjective:

The orchid drapes are a great color for this room.

Note: This is a common adjective. A proper adjective is an adjective derived from a proper noun, such as Danish describing something of or from Denmark, or Victorian describing something of or from the time of Queen Victoria. Proper adjectives are always capitalized.