“Hardened-Off” is a process of moving the young sapling outdoor so that they learn to withstand outside changing temperature and weather condition. These young sapling are brought from nurseries or grown from seed or cutting indoor.
Usually it’s 7-10 days of time to let the plant get accustom to the new surrounding. The goal is to help the young sapling get settled in the outdoor environment.
Please note, when moving saplings outdoors, don’t expose them to direct sunlight on day one.