So you have worked hard for 8 weeks! You have invested money into equipment and possibly genetics; you have invested time and dedication to get to this point. How can you tell when it’s time to harvest your gooey girls? Well ‘fire one up’ and let’s take a look at the best way to be sure you’re harvesting at peak potency. This article will help you understand what happens in the final weeks, so you can harvest for the specific type of high you prefer.

The harvest window is one aspect of the craft which, unfortunately, gets overlooked. As well, many growers simply don’t have the patience to wait-out the last few days to insure max THC content.

Some strains are better harvested before their peak THC production and some are better harvested after their peak THC production.

Robert Clark wrote about trichomes and what they tell us in his book “Marijuana Botany”;

“The elevated resin heads appear clear, since fresh resin is still being secreted, often being produced in the cellular head of the trichome. At this time THC acid production is at a peak and CBD acid levels remain stable as the molecules are rapidly converted to THC acids, THC acid synthesis has not been active long enough for a high level of CBN acid to build up from the degradation of THC acid by light and heat. Terpene production is also nearing a peak and the floral clusters are beautifully aromatic. Many cultivators prefer to pick some of their strains during this stage in order to produce marijuana with a clear, cerebral, psychoactive effect It is believed that, in peak floral clusters, the low levels of CBD and CBN allow the high level of THC to act without their sedative effects.”

What the hell does this mean?

When growing Indica hybrids, unless you want to end up on the couch, it’s best to harvest when the trichome heads are fully formed but before they start to cloud over and turn amber. This could take as little as five days or as long as two weeks, depending on the maturation time of the specific strain. If you allow an Indica to go too long, you can dramatically affect the taste and high. Fortunately, going too long is not a real problem for most people.

I like to study close-up photos taken with a high resolution digital camera; however an inexpensive hand-held microscope works wonders. It almost looks like you are in an alien world when looking at resonated buds using fifty-times-power.

With the Sativa-dominant hybrids, you want to make sure that all the trichome heads are fully formed and also about thirty percent amber. Letting a plant mature beyond this point will risk flavor and the finished smoke may be harsh with very little “high”. There are exceptions; Haze has three different harvest windows, all being very late into flower. It is every grower’s job to learn what he or his patients prefer in the terms of “high”.

This article will not address yields: if you are at the third stage of floral maturity with fully-formed trichomes, we can assume most strains have packed on all their final weight.

Use the guidelines spelled out below to help gauge the best harvest window for your plants based on the trichomes.

1. Fully-formed but still clear will provide a cleaner ‘up’ high with less sedative effect; this is the best window for heavy Indicas. 2. Fully-formed and turning slightly cloudy or milky; this is probably the best time to pick most hybrids available today. 3. Fully formed completely cloudy or milky with at least 30% of the heads turning amber; this is usually best window for the late maturing Sativa’s such as Haze. This is also a good window when using the plant primarily for Hash production.

Take for instance the Jacks Cleaner, harvested at 56 days; all trichomes are still visibly clear with very few turning cloudy. At this point it has a very ‘up’ high and an ‘in-the-head’ buzz. I get some good visuals and the lemon flavor is sour and a tad tart.

See the photo gallery on Flickr

The same plant, left just one more week at 63 days flower; the trichomes have turned milky white and a good portion, about 30-50%, are deep amber – almost the color of cola. Taken at this time, the smoke is heavy and thick, the lemon zing has been replaced with a musty sweet lemon smell that reminds me of ‘Lemon Heads’ candy. The high is now all body high and very much a sedative. We would smoke this only as our nighttime medication. It is almost an example of a plant taken too late; however, we do this because of the medicinal properties she takes-on at this late stage.

Another example is Killer Queen. At 49 days flower, she has a candy-like smell and taste with that same ‘up’ high. If you were to harvest her at 60 days flower, she becomes ‘Super’ Killer Queen, with a more skunk-like smell and a thicker trance-like high.

The mistake to avoid is harvesting before the trichomes are fully formed; most growers who use this method harvest when the majority of the heads are cloudy. Harvesting before this window will produce bud that is less potent, containing less essential oils and trepans, causing your finished stash to take on a grassy or green taste, even if it is dried and cured correctly.

Another good method would be harvesting some of the more mature buds, usually being the upper or main colas. This will allow more light to shine down on the lower portion of the plant, not only will the buds mature further but they will also pack on some extra size.

If you have a nice digital camera with a macro feature, try taking some close-up photos and use a photo editing program such as Adobe. This will allow you to zoom in close so you can see what the naked eye cannot see. If this is not an option, Radio Shack and other electronic stores sell battery-powered hand-held microscopes for about $15.

Take advantage of this information, it will help maximize the results of your favorite strain, or help you determine the harvest window of something new.

Subcool is an expert grower and breeder, and author of Dank: The Quest for the Very Best Marijuana, published by Ed Rosenthal’s Quick Trading Company. He and is a regular contributor to Cannabis Culture and other marijuana magazines. Read Subcool’s Blog.