Are these planters frost proof?

Metal vessels generally withstand low temperatures well, provided drainage is adequate. Heavy copper walls expand and contract safely in cold weather, unlike porous ceramics that crack when trapped moisture freezes.

How do I create drainage holes?

Most historic vessels were not manufactured with garden use in mind. A standard household drill equipped with a suitable metal bit creates necessary drainage without splitting the heavy sheet.

Can copper planters sit directly on soil?

Direct contact with damp earth accelerates the natural oxidation process. Raising the base slightly on bricks or pot feet prevents excessive moisture retention and preserves the lower edges.

How do I maintain the verdigris?

Weathered surfaces require very little intervention to retain their character. Washing away accumulated dirt with plain water keeps the metal stable without removing the desirable green oxidation.