Deciding when to harvest your cannabis plants is one of the most important decisions a grower has to make. Harvesting too early or too late can significantly impact the potency, flavor, and overall quality of your buds. While there are some general guidelines, timing the harvest ultimately comes down to carefully observing the plants and making the call based on your specific conditions and goals. In this post, we’ll go over the major signs to look for when determining the optimal harvest time.
The Flowering Stage
Cannabis plants take between 7-9 weeks to fully flower and be ready for harvest. When the plants switch from vegetative growth to the flowering stage, that’s when the countdown begins. The flowering stage starts when the plant begins focusing its energy on bud production rather than just leaf and branch growth. This shift is triggered by the light cycle changing to 12 hours of uninterrupted darkness each day, signalling to the plant that winter is coming and it’s time to reproduce.
For an indoor grower, you’ll initiate the flowering stage manually by adjusting your grow lights. Make note of the exact date you make this light cycle change, as that marks day 1 of the flowering period. For outdoor plants, this shift coincides with the passing of the summer solstice in late June/early July when the nights once again become longer than the days.
The best window for harvesting is when the trichomes on the buds go from clear to cloudy to amber. Trichomes are the shiny, resinous glands that cover the buds and leaves. These bulbous resin glands contain the cannabinoids and terpenes that give cannabis its potency, flavors, and effects.
Clear trichomes indicate that the buds are still not fully developed. Most strains need at least some cloudy trichomes to be considered in their prime for harvest. Amber trichomes indicate that some of the THC is breaking down into CBN, which creates more of a relaxing effect. Growers targeting a more euphoric, energizing high will want to harvest when most trichomes are still cloudy. For more sedative, couch-lock effects, growers can push it a little longer till more trichomes turn amber. It’s up to your individual preferences – cloudy is a good balance between flavor, potency and effects for most any use.
The small hairs that emerge from the buds are called pistils. Initially the pistils are white, but they slowly turn more orange and reddish as the buds mature. Pistil color can be a good visual indicator that the harvest window is approaching, but should be used in combination with trichome development for deciding exactly when to harvest. Some strains may turn colors quicker or later than others. Relying solely on pistil color can easily result in harvesting too early or too late. Think of them as a general maturity indicator rather than the determining factor.
Buds will swell and put on the majority of their weight in the final 2 weeks of the flowering stage. If harvested too early, your yields will be lower and buds will have a grassy, unpleasant taste. The buds will look loosely arranged without much definition. Allow them to properly form and ripen for maximum bud density and appealing looks. Go beyond the point that the white pistils have mostly turned color – wait until the buds have swollen for highest yields.
In the later stages of flowering, the sugar leaves surrounding the buds will start to yellow, wilt, and die off. This is a sign that the plant is nearing the end of its life cycle and putting all its energy into the buds rather than leaves. It’s perfectly normal and not necessarily an indication of a nutrient deficiency. Letting the plants go until about 30% of the leaves have yellowed results in buds that are fully ripe yet still nicely covered in trichomes. If you harvest too early while most leaves are still vibrant green, you run the risk of undeveloped, immature buds.
As cannabis buds properly ripen, they will firm up, becoming denser rather than loose and airy. A sign that buds are fully mature is that the tightly packed calyxes swell and take on a more rounded shape. Give buds a gentle squeeze to assess their firmness and density. Hard, compact buds are ripe and ready for harvest. Soft, loose buds will benefit from more time to properly mature.
Buds transition from lush green to more subdued colors as harvest time approaches. This fading from green to more gold, red, purple, or brown hues indicates a reduction in chlorophyll as the plant ripens. Most indoor strains will exhibit some degree of bud fade near the end of flowering. The intensity of the fade can vary quite a bit between different strains. Sativas tend to fade more dramatically than indicas. While a pronounced fade can be pretty, it is not necessarily linked to potency. Don’t rely on bud color alone – observe trichomes and bud firmness as well.
As buds mature, the glands become engorged with resin, taking on a swollen, bulbous shape. The buds will look extra frosty and sticky when the trichomes start producing resin in earnest. If your buds look a little dry and lackluster, let them go longer to maximize resin content. The final 2 weeks often bring a surge in oily resin production resulting in dazzling, crystal covered buds glistening with sticky goodness.
In addition to the white pistils turning colors, the actual hair-like structures protruding from the calyxes will begin to take on an amber hue. This is different from the pistil color change and indicates very mature buds. Some strains will exhibit this amber color shift in the calyx hairs earlier or more dramatically than others. It’s another sign that harvest time is closing in, but trichomes remain the best visual gauge.
Many growers choose to flush their plants for 7-14 days prior to harvest by discontinuing fertilizer and only watering with pure pH’d water. This is believed to result in smoother taste by leaching out excess mineral salts from the buds and reducing chlorophyll production. A proper pre-harvest flush is recommended by most growers, but remains a controversial topic without definitive scientific evidence proving its effectiveness. If you opt to flush, factor this additional 1-2 weeks into your harvest date decision.
As you gain more grows under your belt, you’ll learn the nuances of your particular strains and dial in your desired harvest window. There’s no better guide than your own observations and tracking how certain genetics respond in your specific conditions. As you become more in tune with your plants, you’ll be able to better predict when they’ll reach peak maturity and plump up with resinous buds. Learn the optimal look and feel that matches your individual grow goals.
In summary, the keys to perfect cannabis harvest timing boil down to:
- Observing trichome color under magnification
- Pistil color transition
- Bud formation and density
- Leaf yellowing and plant fade
- Resin content
- Pre-harvest flush (optional)
While general guidelines suggest 7-9 weeks of flowering, each strain can have slightly different ideal harvest windows. Carefully checking the above signs beginning around week 6 will help pinpoint the exact right moment to cut down your ladies for beautifully developed buds. Time it right and you’ll be rewarded with heavy yields of flavorful, resin-covered cannabis.
Click here to learn about Cannabis facts and Effects!. For practical tips and advice on Cannabis Clones, check out our posts on How Much Cannabis Can I legally Carry In Canada, From Clone to Harvest: 5 Essential Growing Tips for New Home Cannabis Clone Cultivators in Canada, and From Clone to Harvest: Understanding The Journey of Cannabis.