When is My Cannabis Plant Ready for Harvest

Harvest time is the most rewarding and exciting aspect of cultivating cannabis for many growers. After months of witnessing your plants slowly morph from seedlings into fully bloomed plants, it’s almost time to reach for the trimmers and proceed to dry and cure your bounty. However, it’s important to remain patient and not become too hasty. There are numerous signs you need to be aware of and look out for on both the macro and micro levels to make sure your flowers are truly ready.

Harvesting cannabis flowers at just the right time ensures optimal quality. Doing so too early can reduce both yields and potency, and doing so too late can result in THC degradation and a far more narcotic and sleepy high.

There is a large debate surrounding exactly when to harvest buds. There are general guidelines for each cannabis subspecies in regards to the optimal time. Indica strains are usually ready after 8 weeks of flowering, and sativa strains after a 10-week period of flowering. Autoflowering strains often take approximately 10 weeks after the seedling stage. Although these guidelines can be helpful in estimating when harvest time may occur, more attention to detail is required to make sure you are spot on with your timing.

A slight knowledge of cannabis anatomy is required to make an accurate assessment of ripeness and of when your cannabis flowers are ready to be gathered. Below we explain how several parts of the cannabis plant that display signs that drying and curing are just around the corner.

Fan Leaves Will Turn Yellow

It doesn’t take much anatomical knowledge to identify this change. Fan leaves are the large and wide leaves that serve as energy-forming solar panels for your plant. During the vegetative phase, yellow leaves aren’t a good thing and often point towards nutritional deficiencies. However, if your plant is loaded with flowers, fan leaves will begin to turn yellow and die as much of the resources are directed towards the buds. This is an easy to spot and surefire sign that harvest time is close.

Pistils Will Begin to Turn Red

This is where a little cannabis anatomy can go a long way. Becoming acquainted with cannabis pistils will help you to identify when it’s time to start snipping flowers. Pistils are hair-like structures upon cannabis flowers that emerge from the calyx and can easily be identified with the naked eye. Pistils contain the reproductive organs of the female cannabis plant and will develop a seed if pollinated by a male. These structures are white early on in the flowering phase and turn to darker colours of red, brown, and orange as the flowers move closer to harvest.

If most of the pistils are still visibly white, then it’s too early to harvest and your plants should be left to mature for a little longer. Growers should wait until at least 50% of pistils have turned darker to ensure near maximal THC levels. Begin trimming flowers when 60–70% of pistils have turned dark for the highest levels of THC. Those growers looking for a more stoning and physical high should wait until 70–90% of pistils have changed colours, as more THC will have converted to CBN at this stage.

Resin, produced by important anatomical parts called trichomes, offer signs for the time to harvest, although on a much more micro level.

Trichomes are minute mushroom-shaped glands that mostly occupy the flowers and sugar leaves, although you can find a few on some fan leaves and stalks too. They produce valuable resin that contains cannabinoids and terpenes.

In fact, there are several types of trichomes on cannabis plants, but we can split them into two basic groups for the time being.

1. Non-glandular trichomes—provides basic defence against predators, UV radiation etc. These trichomes don´t produce any resin.
2. Glandular trichomes—produce resin containing secondary metabolites like flavonoids, terpenoids, terpenes and cannabinoids. The resin is the ball on the top of the trichome stalk.

Glandular trichomes with resin are too small to be properly assessed with the naked eye, therefore magnifying tools are required to get a closer look.

Magnification of 40–60x is optimal for resin and trichomes observation. A jeweller’s loupe is a small hand-held magnifying device that can be used to get up close and personal with trichomes. Additionally, a digital microscope will provide a clearer image of the state of your resin, but at more of a cost.

Under magnification, resin on glandular trichomes will appear clear and have a crystal-like look during the early stage of flowering. In this state, the resin is signifying low potency, indicating underripe flowers.

Further down the flowering timeline, glandular trichomes with resin will begin to display a more cloudy appearance and milky colour. When the resin is only half cloudy, flowers are still not fully formed and will have a low odour profile. There’s still some time to wait.

Eventually, the resin will become mostly cloudy. At this stage, they hold the greatest levels of THC and will produce the most intense psychoactive effects. This is the point when most growers will want to harvest their crop.

If left longer, the resin will turn from a cloudy colour into an amber one. Gathering at this stage will produce a more narcotic and physical high.