As a gardener, I’m always buying more ceramic planters for the yard. They’re great for adding color to places where you can’t plant in the ground. But this past winter, I was reminded that pottery can crack and break after a hard freeze. (As someone with a legitimate degree in ceramics, I should have known better, but we all make mistakes.) If you live in a place where frost is likely, you should also take steps to protect your outdoor pots during the cold months.
How do you prevent terracotta pots from cracking?
Clay, which is used to make pottery, is primarily composed of silica, other minerals, and water. When the clay is heated in a kiln to the correct temperature, it is considered vitrified, where the silica turns to glass, all the water is gone, and the piece should be very strong. The important thing is that it cannot absorb water, which is important if you are making a vase for example. However, most pottery planters are made from terracotta clay and are purposely underfired so that water can pass through, which is why those cheap red planters tend to crack and break easily. And unfortunately, even many expensive large glazed ceramic pots are made in bulk and not fired at the correct temperature. As a result, the clay can still absorb water. In cold enough weather, the water expands and freezes, and your pots break.
Ideally, you will bring your pots inside for the winter. Store them in a garage or shed. This also applies to your ceramic pots, garden labels or sculptures, and even your ollas, which are ceramic watering cans that have become popular. Understandably, this is not always possible. You may not have the space, or you may have plants in the pots that cannot stay inside all winter.
Use rocks or wood to raise your planters off the ground to help water drain and hopefully prevent some frost. You can also insulate your planters by wrapping them in burlap or even bubble wrap. Every little bit helps.
