April cold
Fragile plants, those which have had the right to be covered with a white blanket, understand a wintering veil, those which have had a soft straw slipper on their feet, those whose leaves have been gathered by holding them with cotton string, have the right to breathe. Activity resumes. New shoots cannot remain without light in a confined atmosphere without the risk of rotting. It is therefore necessary to remove the protections as soon as the weather permits, to allow the plants to breathe and develop properly.
Nothing indicates that we will not yet suffer some late frost, but if a cold snap can damage the young shoots, a rot unnoticed can harm the whole plant that will not recover.
Again, it's all about observation. One eye on the thermometer, the other on the vitality of the plants under winter protection.