Hardening Off To Prepare Young Plants For Outdoors
Whether you start your own seedlings indoors or buy them at the garden center, it's good practice to spend two or three weeks hardening off to get the tender plants ready for the outdoors.
This process called "hardening off" will help increase the survival rate of seedlings as it reduces the risk of both freeze and sunburn.
In the simplest terms, this process is just setting your sprouts outside and exposing them to a little more sun each day. You start the plants outside in the shade one day and gradually work them up to full sun. Then, weather permitting, they're ready to live outside.
However, as you're performing this simple process, the plants are going through quite a few changes to get themselves ready for outside.
The plants begin to rearrange their cell structures known as chloroplasts. The chloroplasts are what turn light into energy. So as they get more and more light, the chloroplasts rearrange themselves into layers that can absorb the solar energy.
As breezes and wind moves the plant sprouts around, they become stronger. The cells in the seedlings actually become shorter and therefor the plants become stalkier, shorter, and stronger.
As the sun and breeze start to dry the top surface of the soil, the roots have to start doing their work. It's good to let the soil dry out slightly so to cause the roots to venture out and strengthen themselves. However, don't let them dry out completely as it will cause much more harm than good.
There you have it. Hardening off. Start in the shade and avoid areas with strong winds. Gradually work up to full sun over a two to three week period.