What is the purpose of hardening off seedlings?

Hardening off seedlings is a methodical transition of indoor plants and seedlings to the outside environment. Indoor seedlings are grown in a well-stocked area without wind or bright sunlight. They have not yet developed the hardening layers that they develop naturally if they were left growing outside. A sudden exposure to the outside world almost always causes great stress to the seedlings. This is the shock that usually kills the small plants.

The primary objective is to increase the resilience of plants. Exposure to the sun, wind, and atmospheric variations causes the cell walls to thicken. The plants develop a waxy cuticle to protect against ultraviolet rays. The strength of the stem is assisted by movement due to the wind. Gradual change prevents leaching of the leaves and damage to the stem.

Plants face multiple threats without hardening. The soft leaves of plants grown indoors in bright sunlight may shrivel within hours of exposure to full light. Wind will blow flowers or snap delicate stems in an instant. A sudden temperature drop to below 40 degrees F. will kill protoplasm cells of plants. This statement is based on a personal experiment in which I lost two trays of tomatoes last April.

Proper hardening will increase your chances of getting good results in the flower and vegetable garden. Acclimated plants will establish more quickly after planting out. They will have better resistance to pests and diseases. They will bear their fruits earlier in the season. Their root systems will penetrate the garden soil more thoroughly. Your harvests will increase perceptibly.

Read the full article: The Complete Guide to Hardening Off Seedlings