Other than overwatering, one of the most common mistakes new and experienced gardeners alike make when growing vegetables from seed is to not harden off the seedlings before transplanting outdoors.
Have you ever planted your precious tomato or pepper seedlings and a few hours later notice that they are all wilted or the leaves get scalded or turn white? This is often from transplant shock and sunscald. If you do not expose your seedlings grown indoors to the sun and breezes before transplanting them, they will experience transplant shock. Sometimes this can cause the seedling to die or it may have a hard time recovering and have stunted growth. If you don't harden them off first, they will not be used to the sun and can burn easily.
While most seedlings will experience a little wilting after transplanting or in the heat of the day, if you harden off your seedlings first, the wilting should be reduced significantly and you will prevent sunscald from burning up the leaves.
How do you go about Hardening Off Seedlings?
It's very simple. You just want to gradually expose any seedlings you start to the sun and outdoor conditions. To do this, first set them in dappled shade for a few hours (or put them outside on an overcast day), and then incrementally increase the amount of sun they receive for a period of several days. Start with a 1-2 hours of sun until they start to wilt, then put them in the shade, then increase the amount of time they sit in the sun gradually to a full day over a week's time. Make sure to protect them from harsh winds or heavy rains during this time. Then for the last night or two, leave them outside so they can also get used to the cooler nighttime temperatures.
We recommend planting in the evening or in the early morning so the plant has time to recover before the heat of the day with full sun. Overcast days are the best time to plant if possible. Sometimes we'll even shade our recent transplants with a tall pot so that they can have a day without the sun beating on them after transplanting.
Learn more about hardening off seedlings
and lots of other growing tips here:
How to Grow Peppers »
Peppers are easy to grow from seed!