The gradual process of adapting indoor-grown seedlings to outdoor conditions before transplanting.
Seedlings started indoors grow in a protected environment with stable temperatures, limited wind, and relatively gentle light. Outdoor conditions are much harsher, exposing plants to direct sunlight, temperature fluctuations, wind, and changing moisture levels.
Hardening off allows plants to adjust gradually. Over several days, seedlings are exposed to increasing amounts of outdoor light and weather, helping them develop stronger stems, tougher leaves, and greater resilience.
Without this transition period, seedlings often experience stress, slowed growth, or damage after planting outdoors.
Hardening off reduces transplant stress and improves the survival rate of young plants. Taking a little time to acclimate seedlings before planting helps them establish faster and grow more successfully in the garden.