How to Tell When Cannabis Is Ready to Harvest

Seed banks often provide approximate harvest dates for their strains, giving you a general idea of when your plants may be ready. Additionally, the genetics of a strain can help you better estimate the time it will take for your plants to reach full maturity.

Sativa strains typically have longer flowering periods compared to indicas, reflecting their origins in regions with extended summers. For example, our Shining Silver Haze flowers in around 11 weeks (a short period for a Haze variety), whereas our Special Kush 1 flowers in just 7-8 weeks.

The most reliable way to determine if your cannabis is ready for harvest is by observing the plants closely. Mature cannabis shows several signs that it’s ready, including:

Yellowing Leaves

During the vegetative phase, yellowing leaves can indicate nutrient deficiencies or pest issues. However, during the flowering stage, it’s natural for older leaves to turn yellow. This occurs as the plant redirects its stored nutrients and energy toward developing larger, denser buds.

In healthy plants, yellowing begins with the larger fan leaves at the bottom of the canopy and progresses upwards. As the plant matures further, even smaller leaves closer to the buds may yellow. To ensure top-quality harvests, aim to collect your buds while the flowers are still vibrant and green—before yellowing spreads to the sugar leaves or buds.

Note: Depending on the genetics and environmental factors (such as cooler temperatures during flowering), your plants may develop pink, purple, or even black hues as they mature. This is entirely normal and adds to the plant's unique character.

Orange Pistils

Remember the white pistils (hairs) that appeared when your plant first began flowering? These are the reproductive organs of female cannabis plants, designed to catch male pollen. As the plant matures, the pistils change color from white to shades of orange or amber. Most growers choose to harvest their plants when about 90% of the pistils have turned orange, as this is when THC levels are at their peak.

Plump Calyxes

Calyxes are the small, resin-rich bulbs that house a plant’s pistils. Besides forming the structure of cannabis flowers, calyxes are good indicators of maturity. As flowers develop, calyxes swell and become plump, particularly if the plant has gone unfertilized for an extended time.

When the calyxes look swollen, with their pistils protruding in vibrant orange hues, it’s a good time to bring out your microscope or jeweler’s loupe to assess the trichomes. This final inspection will confirm if the plant is ready for harvest.

Milky, Amber, or Clear Trichomes

The most precise way to determine harvest readiness is by examining your plant’s trichomes under a microscope or jeweler’s loupe. Trichomes are the resin glands responsible for the frosty, sticky coating on cannabis flowers. Up close, they resemble tiny glass mushrooms or beads. As your plant matures, trichomes shift from clear to milky white and finally to amber.

For most growers, the sweet spot for harvesting is when about 70% of the trichomes are milky, 15% remain clear, and 15% have turned amber. At this stage, the flowers are believed to deliver the highest THC potency, producing a pronounced head high. If you wait longer and allow more trichomes to amber, the buds may have higher CBN levels, promoting a more relaxing, physical effect. On the other hand, buds harvested with mostly clear trichomes may deliver less potency and a more subtle, clear-headed experience.