Good question, and one that has bothered quite a few people, as I am asked this every couple of weeks on my show.
1 Indirect Light:
A better discription would be "second hand" light. A brightly lit area where light that has come into the room, but not directly in a path from the sun. Bounced of a wall for instance.
2. Low Light:
Light from a southern facing window, or a ways away from any reflected light.
3.Diffused Light:
Light that has been filtered by some source. Blinds or
tree branches for example
Low light or shade:
A area where you would want to turn on a light to read.
4. No light, (as in what Christmas
cactus needs to
flower):
Means absolutly total darkness for what ever specified amount of time. Light from a street light down the block could be enough light to keep certain
plants from blooming. Perhaps tucked away in a closet, or under a black painted box.
5. Full or direct Light:
An area that can cast a shadow for more the 3 hours a day, the rest of the day being in at least indirect light.
6.Partial shade:
An area that recieves less then 3 hours of morning or evening light (No noon day direct sun) Most
plants the require partial shade will do well in difused or filtered light as well.
Hope this helps
Mike