Flowering is finally about to come to an end and now It’s only a matter of trimming the buds that are perfectly ready. But at this point lots of my clients have doubts. And I dare say that some others, not exactly novices, don’t know how to find out the best moment to reap the cannabis fruits either.

Harvest time

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La cosecha


After about three months indoors or some long six months outdoors, the time has come to reap the fruit of our work. After a vegetation period during which we gave shape to our plants, fought the springtime plagues and used fertilizers to fight the shortages that appeared, flowering is finally about to come to an end.

Now It’s only a matter of trimming the buds that are perfectly ready. But at this point lots of my clients have doubts. And I dare say that some others, not exactly novices, don’t know how to find out the best moment to reap the cannabis fruits either.

The truth is there are several methods, all based in observation, but there is one that seems to have all of you captivated: checking how dark the pistils or the white hair on the buds are. This sign of ripeness is one to take notice of, but not exclusively, and that’s the point many of you miss. You can see in the picture a bud that will take several weeks to reach its maximum yield, while in picture number 2 the bud is in the perfect moment for harvest.

La cosecha

La cosecha

Some customers tell us they have already trimmed the buds after all the hair turned brown, but then the buds shrank dramatically once dried up. The ‘high’ obtained was smooth and the taste and smell were not what they should have been. All because of an early harvest. We should remember that the lack of watering, a sudden change of temperature or a very windy day, amongst other causes, can oxidize the pistils and lead you to make a mistake that can’t be fixed.

In general, when more than half the hair is dark and curled the plant shows a high THC level and its effect will be more cerebral, creative and lively. Around 90% of brown hair (or reddish, or even pink or purple, depending on varieties) means the TCH has degraded to CBS and the effect will be relaxing, narcotic and medicinal. Another visible sign are the leaves turning yellow from down up. The plant is reaching the end of its vital cycle. Its goal now is reproduction, but it has not been able to culminate it due to lack of pollen, so it produces more and more resin, hoping to perpetuate itself. Its whole energy is focused on flowers and it uses the reserves from the bigger leaves not caring about them anymore.

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This yellowness is another indication, but it is of no use to identify the perfect harvest time either, when considered alone. A very fertilized plant, or a highly hydrogen-charged one, might not turn its leaves yellow and instead reach harvest time with green leaves. On the other hand, if marijuana enters the flowering stage with a nitrogen shortage, its leaves will turn yellow earlier because the plant will have started consuming them. The nitrogen shortage might be due to lack of fertilizing during its vegetation cycle.

The most reliable and accurate technique is observation of trichomes through a magnifying glass or microscope. These tools are sold for around 10 euros and they will come handy not only for deciding when to harvest, but also to identify plagues. So, get hold of either of the two. In my opinion they are as fundamental as a thermohygrometer can be to an outdoor plantation. Trichomes are the glands where marijuana resin is produced, and in resin we find the cannabinoids and some terpenes that the plant uses as defence against some herbivores who might not be as fond of the effects of THC as we are. The plant can also use them as solar protection or to obtain many other benefits. Through our magnifying glass (I use a 40x one) we can observe their structure. They are like tiny mushrooms, formed by a stalk and a head with the shape of a sphere or a balloon. Depending on the colour of the head we can guess the degree of ripeness in the plant. The first glands that form are tiny heads over the buds, nearby leaves and pistils that don’t even have stalk. As flowering advances, the trichomes develop and grow, and they mature.

La cosechaIn early stages the heads are transparent, like drops of water, and there are no acceptable THC concentrations yet. Later, they will turn milky white, so you won’t be able to see through them. If you check regularly on the process you will see how they gradually shift from transparent to milky white. When most of the trichomes look like this, that’s when the THC content is at its peak. The moment white trichomes start turning amber, they are indicating the flowers have reached their resin and THC peak and they are about to degrade to CBN, and therefore the ‘high’ will be heavier and relaxing. This should help you find the harvest time most to your liking, depending on the chosen variety and the effect sought. The same variety and even a clone reaped within a week’s difference changes significantly in terms of taste, power or effects. If you are the kind of grower who constantly changes the variety of your weed, I recommend the harvest to take place when a majority of the trichomes are milky white. If you, on the contrary, are selecting genetics through clones, the best way to do it would be to grow in different moments and look for the one that best fits to what you are looking for, and then write down the dates of the trim. For instance, with an Indica variety you could clip on intervals of 4 days and get 3 to 4 yields of different quality, weight, power…

In the case of indoor plantations, it is better to get used to keeping a grow journal. It is essential to write down when the light period has been changed. I can assure you that only about 10% of my customers do so. A journal is an important tool that is worth more the more crops you keep record of.

All seed banks provide an estimate of the growing time to both indoor and outdoor crops. As there are several phenotypes it’s not painstakingly accurate but it is close. If you buy an Amnesia of 85 days flowering and you harvest on the 60th… it won’t be right. Adjust to these marks within a margin of a week earlier or later for psychedelic or medicinal effects respectively.

I will add, now that purple plants are on the rise, that is possible for their pistils to be pink or violet. As a rarity, in some variety also trichomes can be sort of blue instead of milky white. Treat them as if they were white to judge the ripeness of the flowers.

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Success depends on observation of all the factors I just explained. Watch all of them closely and adjust the moment of harvest depending on what result you are trying to obtain.

It is necessary to clean the roots to ensure a clean taste and smoke. The times for these actions vary depending whether we are cultivating on soil or using the hydro, but thanks to this process we clean the nutrient excess from our plants, allowing them to finish up their reserves so that we don’t feel the taste of the fertilizers when consuming what we reaped.

The simplest rule is to add an amount of water that is three times the pot’s capacity. So, 7 Litre pots will need 21 Litres of water for the roots to be clean. In hydro, it’s as simple as to recirculate with water only, and for outdoors, use 5 to 10 times the amount of water you usually use for irrigation.

There are products on the market that will make this task easier. It is cumbersome, in indoor plantations, to move the plants into the shower to clean the roots. Atazyme by Atami, Power Zyme by Hesi and Grotek’s flushes or Flawless Finish by Advanced Nutrients, amongst others, will help you obtain the same result or an even better one, just by watering to the dose recommended by the brand or producer. From that point on, use only water for the rest of your flushing period. Root cleansing should be performed some time before the harvest. Ten to fourteen days before, in the case of soil, or seven to ten days, in the case of hydro. If you know the variety already or you start from a clone, there will be no problem. If that is not the case, you will have to calculate the reaping time using all the tools I described in the article. I hope I have helped you to determine when to reap those buds that you grew with such love and dedication 😊.

Next week, we will discuss the trimming itself, and the best conditions to dry your weed.

Have a nice and green week!

Gorka Aguirreche, El jardín de la Alegría Growshop, Salamanca.