Hardening-Off
This refers to the process of gradually inuring plants to a cooler temperature, after they have been subjected to heat, either for the encouragement of growth, for propagating purposes, or for forcing. It is most largely practised in spring, with bedding and other plants, that are to be cultivated throughout the summer in the open air. To avoid sudden checks to tender foliage or flowers, it is important that Hardening-off should be conducted by gradual steps.