If you want your home-grown cannabis to be truly top quality, you need to harvest the plants at the peak of maturity. If you harvest too early, you may lose some of the cannabinoids. Overripe plants, on the other hand, lose potency as THC degrades into CBN. So when should you harvest cannabis to achieve the best possible quality after drying?
How long does cannabis flower?
.png)
How long it takes cannabis to mature depends primarily on the variety. Most modern varieties mature after approximately 60 to 70 days of flowering. However, there are also cultivars with a flowering time of around 45 days, as well as varieties that need to be left to flower for 90 days or more. When growing indoors, this period is counted from the day you switch from the vegetative light schedule to the flowering schedule.
In our latitudes (48°33' and 51°03' north latitude), cannabis grown outdoors begins to flower during July and August and must mature before the arrival of cold weather and the first frosts. It is therefore advisable to choose outdoor varieties with a short flowering time of up to 60 days.
The above applies to “classic” photoperiod cannabis varieties, whose flowering depends on the length of the day and night. Autoflowering varieties (autoflowers) are distinctive because they flower independently of the photoperiod. With autoflowering varieties, it is therefore not the flowering time but the entire growing cycle that is stated. This usually lasts 8–10 weeks, although some autoflowering plants (especially Haze varieties) may grow for as long as 12 to 14 weeks.
Fast varieties are hybrids between photoperiod and autoflowering varieties. They respond to changes in day length in the same way as classic cannabis, but have inherited a shortened flowering time from their autoflowering parents. Fast cultivars usually mature after 7–8 weeks of flowering.
You may also be interested in: Photoperiodism and flowering in cannabis
How to recognise mature cannabis
Always treat the flowering time stated by the breeder as a guide only. Every plant is unique, and the flowering and ripening time can vary by several weeks between individual plants. This is true even if you are growing plants from seeds of the same variety from a single pack. The speed of flowering is also influenced by external factors such as climate and nutrition. Most growers determine the exact harvest time by the colour of the stigmas, the maturity of the trichomes and the overall appearance of the plant.
Stigmas – the white hairs on the flowers – enable female plants to catch male pollen. As the plants mature, the stigmas gradually turn brown. The maturity of a plant can be estimated to some extent from the proportion of dark stigmas. It is generally stated that cannabis is mature when more than 70–80% of the stigmas have darkened. However, this method is not always entirely reliable. Some varieties may reach peak concentrations of active compounds earlier or later.
A somewhat more accurate way to estimate the right time to harvest cannabis is to monitor trichome maturity. Glandular trichomes are microscopic glands on the surface of plants. Their round heads contain resin rich in cannabinoids, terpenes and other compounds for which cannabis is valued.
Trichomes can be seen clearly with a magnifying glass offering at least thirty-times magnification or with a camera macro lens. Trichomes at peak maturity have milky, cloudy heads; immature trichomes are transparent, while overripe trichomes are amber in colour. Cannabis is mature when most of the trichomes on the flowers are cloudy and the first amber heads are beginning to appear.
In addition to the colour of the trichomes and stigmas, the approaching harvest can be recognised from the overall appearance of the plants. Some varieties may develop beautiful combinations of red, purple and blue before harvest, while the leaves of others simply turn yellow. Another sign is the rounding of the bracts (small leaves) around the stigmas, making the buds look as though they are covered with small balls. However, flower morphology can vary between different varieties. If new growths (known as foxtails) appear on already mature flowers, it is probably time to harvest.
You may also be interested in: How to dry and store cannabis correctly
If you are just starting to grow cannabis and are worried that you might not get the harvest timing exactly right, there is no need to despair. The truth is that it is not necessary to identify the exact harvest day in every case. Some growers harvest slightly earlier to preserve certain terpenes, while others wait a few days to give their cannabis a heavier body and more sedative effects. Therefore, in addition to following our guide, use your nose and your growing instincts.
Are you looking for more growing guides, articles about the history of cannabis or information about its health benefits? You will find all this and much more on the HiSeeds blog.