Copper Garden Planters Through a Vermont Winter

Copper handles cold well. The metal itself is not damaged by freezing temperatures. It expands and contracts with the cold, but the gauge I use for planters is thick enough that this does not cause cracking or splitting. The risk in a Vermont winter is not the copper; it is the soil and water inside the planter.

The freeze-thaw problem ¶

When water in soil freezes, it expands. In a planter with drainage holes, most of the water drains before it can freeze, which is why drainage holes are not optional on any planter I make. But if the drainage holes get blocked by roots or debris, water can pool at the bottom of the planter and freeze solid. The expanding ice puts pressure on the seams and, in a severe case, can open a soldered joint.

The fix is simple: clear the drainage holes before the first hard frost. Pull the plant, shake out the loose soil, and check that water runs freely through the holes. If you are leaving plants in the planter over winter, check the holes monthly.

What to do with the planter itself ¶

You do not need to bring copper planters inside for winter. They are designed for outdoor use year-round. If you want to slow the patination process. If you like the current colour and want to preserve it. A coat of paste wax applied in late October will help protect the surface through the wet months.

If you are leaving the planter empty over winter, store it upside down or on its side so water cannot pool inside. This is more relevant for the smaller planters; the larger ones are heavy enough that moving them is not practical, and they are fine left in place.

What to expect in spring ¶

After a Vermont winter, a copper planter will have developed more patina than it had in autumn. The freeze-thaw cycles and wet snow accelerate the colour change, particularly on the bottom and sides that are in contact with the ground or snow. This is normal and, for most people, welcome. The planter looks more settled and established.

If a seam has opened over winter. Which is rare but possible if drainage was blocked. It can be resoldered. Email me with a photo and I can tell you whether it is a repair I can do or whether it is something a local plumber with soldering experience could handle.

Copper planters in Vermont are a long-term investment in the garden. The ones I made in 2016 for a client in Stowe are still in the ground, still draining, and considerably greener than when they left the workshop.