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When is the right time to harvest cannabis plants?

July 19, 2016

Harvesting your cannabis garden is often the most exciting time when it comes to growing. All your previous efforts culminate in this moment when the decision is made to cut your crop. Because so much is riding on the decision to harvest, it’s important to understand what is happening on a chemical level with the cannabis plants. What do you need to consider when harvest approaches to ensure the best crop possible?

There are several factors, but each vary in accuracy:

  • The flowering time recommended by the breeder
  • The color of the stigma (the hair-like strands that cover the bud)
  • The color of the trichomes
Cannabis anatomy: The parts of the plant

The time recommended by the breeder is actually the least accurate measurement of when to harvest. Breeder information should be used to help determine your garden schedule, but it has less to do with when the plants are in peak harvest.

A more accurate factor is looking at the stigma. You can make a solid estimate of when to harvest by tracking the stigma’s change in color from white to orange.

Observing your buds’ trichomes offers the most accurate indication of when cannabis is ready to harvest. It is in the trichomes that the actual science behind when to harvest exists.

Determining when to harvest your cannabis crop

Determining when to harvest your cannabis crop

You’ll need a microscope to actually observe the trichomes. Handheld microscopes ranging from 30x-100x will allow a clear view of the color of the trichomes and can be purchased at any growing supply store. With a microscope in hand, a grower can see the transformation as the plant reaches peak potency.

In this stage, the trichomes go from clear to opaque and end in amber. During this change the trichomes reach their maximum THC content and then begin to break down due to exposure to oxygen and UV rays. The result is CBN (cannabinol).

How Strain Genetics Influence THC:CBD Ratios

Though CBN is a result of THC degrading, like other cannabinoids found on the cannabis plant, it has its own unique set of benefits. CBN has been linked to providing aid for insomnia, pain, and inflammation, as well as many other benefits. It does not, however, have any psychoactive effects.

High CBN levels are commonly associated with the term “couch lock,” which speaks to its highly sedative qualities. THC, on the other hand, is very psychoactive, cerebral, and less fatiguing, while offering an array of medical benefits.

Regardless of CBN’s benefits, most growers try to prevent the THC trichomes from degrading into CBN.

Ensuring your cannabis has levels of THC when it’s harvest time

Ensuring Your Cannabis Has Levels of THC When It’s Harvest Time

To harvest your crop with the highest levels of THC, it’s best to start by paying attention to the stigma. Once the stigmata start to change colors, it’s a good time to begin observing the trichomes through a microscope. Look for clear trichomes, which indicate that the buds are young and still developing. From this point forward it’s both a fun and good idea to observe the trichomes daily. It’s good practice to look at different bud sites on the plants, as the top colas might reach maturity faster than the bottom buds.

Eventually there will be a shift from clear trichomes to an opaque white, which indicate full maturity. At this point the trichomes are no longer producing additional THC. Unfortunately, all trichomes do not develop at the same rate and you will begin to see some amber trichomes before you see a consistent opaque. Once amber trichomes appear, CBN is now starting to develop as a result of the THC breaking down. You can presume at this point that you’ve reached maximum THC and your plants are safe to harvest.

If you have the time and observe less developed buds lower down on the plants, you can split the harvest in two. Dividing your harvest allows the bottoms of the plants to continue to develop after the tops have been harvested, which helps increase overall bud quality and yield.

Conflicting views on when to harvest cannabis

Conflicting Views on Picking a Cannabis Harvest Time

It’s important to note that every gardener has a different opinion on when to harvest their cannabis plants. Some gardeners like to harvest earlier while others prefer later, which is why an understanding of the science of cannabis botany is so beneficial. Growing cannabis is a continual learning process. Depending on the crop, an ideal harvest may be early or later in the trichome development. Because of this variability, growing the same genetics and working with the same strains for more than one harvest is encouraged.

If you’re curious to explore the benefits of CBN but are unsure about letting your plants’ THC content diminish, you can explore other options. Unfortunately, CBN products are not yet easy to find but they do exist. Mary’s Medicinals out of Colorado produces 5 mg CBN capsules that are an excellent way to give you a clear understanding of the effects. Other products include Ethos sleep tincture, which has increased levels of CBN as well as THC, valerian root, and chamomile. Ironically, a less conventional way to explore the benefits of CBN is to ingest cannabis that has been improperly stored or harvested late.

How long is my weed good for? Leafly’s guide to storing cannabis
Trevor Hennings's Bio Image
Trevor Hennings

Trevor is a freelance writer and photographer. He has spent years in California working in the cannabis industry.

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