The hardening off process is aided by:

The hardening off process refers to the gradual acclimatization of plants, particularly seedlings, to outdoor conditions before permanent transplanting. This process is essential for reducing transplant shock and ensuring the plants can thrive in their new environment.

Reducing soil moisture content is critical in the hardening off process because it mimics the conditions plants will face in the outdoors. When seedlings experience slightly drier conditions, they develop stronger roots and a more resilient structure. This adjustment helps them adapt to variable weather conditions they will encounter after transplanting, like fluctuating moisture levels.

In contrast, applying fertilizer may promote rapid growth and lush foliage, which can make seedlings more susceptible to stress when they are eventually exposed to harsher outdoor environments. Lowering the pH of the soil could affect nutrient availability but does not specifically contribute to the hardening off process. Meanwhile, root pruning, while it can be beneficial in certain contexts, does not directly assist in acclimatizing plants to outside conditions. Reducing moisture levels prepares the seedlings for the realities of outdoor life, making it the most relevant factor in the hardening off process.