How do I know if I am providing the right amount of light for my seedlings?

Question:

How do I know if I am providing the right amount of light for my seedlings?

Answer:

Careful observation of your seedlings will help you determine if the light levels are appropriate.  Seedlings that are not receiving enough light will stretch and lean towards the light source.  Use a brighter fixture that provides more lumens, replace fluorescent tubes with new brighter bulbs, or simply move the fixture closer to the seedlings to increase the light levels.

If seedling leaves turn yellow or brown and burn starting with the upper leaves, they may be receiving too much light.  You can swap the fixture for one that provides fewer lumens or simply adjust the fixture so it is further away from the seedlings.  The lumens per square foot shining on the plants drops significantly by pulling the fixture just a few inches further away from the plants. 

Learn more about providing supplemental light for seedlings indoors in this article: Growing Indoor Plants Under Supplemental Lights.