What is some good methods for protecting feijoa trees from frost? As the fruit gets destroyed by frost each year
Protection From Frost
Certified GKH Gardening Expert
The article below is about winterizing Fig Tree's but the technique would apply in your case.
Be sure to use cloth and not plastic to cover the plants during the frosty nights. Remove during the day. Plastic will not allow the moisture that collects under the plastic to evaporate and will cause the plant to freeze to the plant. Cloth allows for evaporation through the material. If you have a lot of pots you could consider buying a smudge pot to keep the air walmer around the plants.