How do you know when to harvest?

title??

well?

read the farmers almanac.

Look at the triches, they'll tell ya if it's ready.

lol im pretty sure if he doesnt when to know to harvest he probably doesnt know when the trichs look like theyre good enough to harvest

or what a trich is for that matter

When your plants start talking to you.

look up trichomes on google images, those are where the thc is so get at least a 15x-20x magnifying glass look at the trichomes, they will start clear but as the time comes they get more opaque so when they look milky white and your pistills are about 2/3 orange you should harvest. you should go to greenmanspage.com and read 'When to Harvest' under specifics.
hope that helps

This is a very basic answer that will get you in the ball park. Knowledge is power and I "highly" suggest you invest in a grow book and grow dvd.

Read the FAQ and use the search function
Monitor the time she is in the flower mode
Watch for your pistals start to turn brown/red and shrivvle up a bit
Invest in a 30x jewelers loupe or 60 - 100x scope from radio shack
1st sign of an Amber tric....FLUSH with water 3x the size of the container
Wait 4 days and cut down

There is much more to growing and harvesting and it will take a long time and a good number of grows to become good at it. Many will get lucky here and there but lack of knowledge eventually takes over.

get ed's book.
Marijuana Grower's Handbook: The Indoor High Yield Guide