Book 29, Question 32
What does it mean to harden off seedlings?
Plants raised indoors are tender, and sudden wind, sun, and cold can damage them.
Hardening off means slowly introducing them to the outside over a week or two. Start with an hour in a shady, sheltered spot, then add more time and sun each day. The leaves toughen up and the plants adapt. Skipping this step can scorch or kill seedlings.
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Quick answers
What does it mean to harden off seedlings?
Hardening off is a process of introducing the seedling to an outdoor, somewhat protected environment for a few hours a day, increasing exposure over a period of 7 to 10 days.
Harden-off seedlings before planting them to reduce transplant shock.
Hardening off is the process of slowly introducing plants to outdoor conditions after being started indoors.
Sources: Oregon State University, Cornell University, University of Illinois
More fun facts
- Hardened-off plants may wilt when first exposed to full sun, but they generally recover within a day or so.
- About 2 weeks prior to transplanting plants outside, it is recommended to start the hardening off process.
- A cold frame provides an excellent environment for hardening off transplants.
- The goal of hardening off is to cause plant cell walls to thicken, changing soft, succulent growth to firmer, harder tissue.
- The easiest way to harden transplants is to place them outside in a shaded, protected spot on warm days, bringing them in at night.
- Hardening off reduces the growth rate and thickens the cuticle and waxy layers.
Sources: University of Minnesota, University of Illinois, UMD, University of Nebraska
Questions kids ask
Why do gardeners harden off young plants?
The goal of hardening off is to slowly expose the plants to the elements of the outdoors to strengthen the plants.
Source: University of Illinois