Our stoneware ceramic (Viducci's terracampa and Viducci's oxide series) is absolutely frost resistant due to the very high firing temperatures of around 2250° F. Our terracotta planters are fired at about 2000° F which makes them one of the most frost resistant terracotta products. Our robust and light isi™ planters are as frost resistant as our high quality terracotta.
But always keep in mind that freezing water can even destroy metal tubes!
The following 3 simple tips will help to avoid water logging:
1 To keep the drainage holes free put a layer of gravel or perlite into the planter and cover it with a piece of gardening fleece before filling up with soil.
2 Put the planter on pot feet during winter. Pot feet are available in terracotta, terracampa and glazed – but simple wood ledges will do too.
3 Cover the soil with some straw or mulch to keep it dry during rainy periods in winter.
These are at the same time the best tips to protect your plants during frost periods – plus wrapping them with gardening fleece.
If necessary, clean your planters with a soft brush and some water. Don't use any solvents.