Talking about light levels and what those words low, medium, high actually mean.

Hi.  Today I thought I'd try changing the appearance of the text, mess with color, and all that.  How do you like it?

The fourth type of information you need to make watering decisions is the amount of light the plant is getting. This is, incidentally, another Secret of the Green Thumb:

THE MORE LIGHT AVAILABLE, THE MORE WATER IS USED
                        Conversely,
THE LESS LIGHT AVAILABLE, THE LESS WATER IS USED

When there's plenty of light, the plant's factories are humming along at high speed and using lots of water; when the light is low, the activity level is correspondingly low, and so is the use of water.

Also, high light intensifies evaporation of water from the soil, as well as from the leaves; when the light is low,  evaporation drops.

    So how do you know what level to call the light?

High light is what you would find next to a window where direct sunlight comes in for two hours or more per day, usually a south or west window.

Moderately high light would be near a window with no direct sun, or sun less than two hours per day, usually a north or east window, or a high-light spot that's filtered by curtains, trees, etc  into a low-light spot.)

Medium light is a general condition of working light found in most offices, under which you can easily read.

Moderately low light is a situation in which you can still read, but you wish you had a little more light.

Low light is where you can read, but not for very long.

And if you can't read in the spot, there's not enough light for any plant; this light level is otherwise known as none at all (from the plants' point of view, of course.)

------------end of excerpt from THE COLOR OF YOUR THUMB HAS NOTHING TO DO WITH IT

This short video also brings up the important point that you're going to water more when the light is higher, and less when the light is lower, and super, super important -

 the major trick to keeping plants in low light is to allow them to get dry all the way to the bottom of the pot.

There's also a discussion about why you need to know what kind of plant you have - so you can find out what level of light the plant needs.
                                                                                          (by Marlie Graves)