The best time to harvest marijuana plants is when THC production has reached its maximum. A rough guide as to when to harvest is to wait until 50%-80% of the white pistils (hairs) have turned dark (usually brown or red). But a better method of determining when to harvest is to wait until certain trichomes on the plant have matured.Trichomes are small appendages that look like hairs, they are produced by marijuana and other plants. Some trichomes on marijuana plants develop a resin gland at the top. These trichomes are a rich source of THC, and monitoring them will allow you to best judge when the plants are ready for harvesting.
On marijuana plants, trichomes with resin glands form in the highest concentration on buds. They start out clear, turn a milky color, then turn amber (light brown). To best judge when to harvest, wait till about a week or two before the expected harvest time (just before you go to water only feeding) and look at the trichomes on the largest buds on each plant daily. All you need is a microscope rated at somewhere between 20x to 70x.

nice post man! any ideas where to get a good hand microscope from? im in uk so i use ebay for a lot of things but i only find 30x, 60-100x or 45x! i found one before on a site that was 30-100x and was less then £5! but i cant find it now. where can i find one now? thanks

yall have radioshack there? any of these are good http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=hand+microscope&_sacat=See-All-Categories

thanks for that! no radioshack here. back to good old ebay i guess!

haha never fails me! i love to ebay!

me too, just spent £270 on equipment in the last 12 hours! maybe i should take a break lol

its fun and addicting! i could spend a whole lot! i spent a G my first grow.

most def SB they mature and get more as the plants mature.

Now here's a question for the gurus: I had originally planned to harvest the plants in our DIY aeroflow type unit and reveg those plants for a few weeks. Trouble is, after problems caused by a bad PH meter (potassium def/nute lock), another problem caused by a light timer (it started giving the plants 45 minutes of light in the middle of the dark cycle so the plants became very confused), bottom line is some of the plants only ended up two feet tall, and now so much of the plant has become involved in flowering that it's hard to see much left of the plant to reveg after harvest. (for example a 24" main stem with only the bottom 8-9" exposed below the flowered section.) Has anyone run into this before and is there a workaround?

FMIF, ops