Picture 1
Picture 2
Picture 3
Marijuana Trichomes
Trichomes are small appendages that look like hairs. They are produced by marijuana, and other plants. Female marijuana plants produce certain trichomes that are a rich source of THC. These trichomes can be found in their largest concentration on the buds. They start out clear, turn a milky color, then turn amber (light brown).
A majority of the trichomes in picture 1 are clear. After the plant has flowered for a few weeks, the trichomes start to turn a milky color (picture 2). After a few more weeks, they will be totally milky in color. In the later stages of flowering, trichomes will turn to a light brown color (picture 3). The amount of time required to get to this point depends on the marijuana strain and the growing conditions.
When to harvest your plants will depend on the desired effect you want. In picture 2 you can see the stems have started to turn from a clear color to a milky translucent color. For maximum THC content and a more cerebral and energetic high, harvest your plants when about 50% of the trichomes have turned from clear to a milky translucent color.
Waiting until about 50% of the trichomes have turned from a milky translucent color to amber will result in marijuana that produces a combination of cerebral and body intoxication. If you harvest when a majority of the trichomes are amber colored (picture 3) the marijuana will produce more of a sleepy body stone than it would have if it were harvested earlier.
Almost all marijuana strains will have trichomes that will turn color, but some people who grow marijuana have come across strains that don't.
Note that trichomes are too small to be seen properly with the human eye. To see them properly, use a pocket microscope rated at somewhere between 20x to 70x. The greatest concentration of trichomes can be found on the growing buds.
please link to this page not directly to the images
images by joop dumay, from marijuana horticulture
see this for information about harvesting marijuana