Hitting Peak Potency: When to Harvest Your Cannabis Plants

When is the best time to harvest your cannabis plants to hit peak potency? It's not just about a growers' intuition. With the right know-how and a helpful tool, you can hit peak THC-levels even with your very first grow. 

Determining the perfect harvest time comes down to four factors:

  1. Strain averages 
  2. Botanical indicators
  3. Trichome color
  4. Weather (outdoor only)

Botanical Indicators that Tell You It's Time to Harvest

As your plants reach maturity, you'll begin noticing several changes to their physical appearance. First, the fan leaves will begin to yellow. Fan leaves are the largest sets of leaves that you'll discard at harvest time. Pay close attention to the leaves immediately around the flowers. When these leaves begin to yellow, it suggests you are getting close to harvest time, not facing a nutrient issue. 

The second sign is the stigmas. These are the long hairs covering cannabis flowers. They will start off light yellow or white, but as the flowers mature, they begin to turn dark red, orange, or brown. 

Monitor the plant every day as it progresses through these new changes. Once you've noticed yellowing fan leaves, followed by darkened hairs, you have reached the end of your journey. Based on these two indicators, you can imprecisely pinpoint the perfect time to harvest. 

But what if you want to take your harvest to peak potency? With the right grow room tool, an LED magnifying loupe, you'll have a microscopic view of cannabinoid development within the trichomes.

Trichome Color Development Predicts Ideal Time to Harvest Cannabis

Catching peak potency requires a grasp of trichome development. Trichomes are the microscopic glands that coat the outside of the cannabis flower. To the naked human eye, it appears like a coating of crystals. With a jeweller's loupe or magnifying glass, trichomes appear like small mushroom shapes or the pin on a Google map. 

Trichome color predicts THC potency. As you reach the end of the flower cycle, start inspecting buds daily. Using your handy jewellers' loupe, you'll be able to see the color of the trichomes. 

Clear Trichomes

Trichomes begin life as clear and transparent. The plant has already produced some cannabinoids and terpenes within these crystal clear glands, but it is nowhere near the levels most cultivators want. The trichomes will likely contain mostly precursor cannabinoids, like CBN, which are non-intoxicating. If you want THC-rich buds, clear trichomes indicate your plants need more time.

Milky Trichomes

Continue to monitor daily, and you'll notice the trichomes begin to turn cloudy. This shift means harvest time is getting close. Cloudy trichomes signal an increase in THC and peak terpene production. Most growers suggest harvesting once 75 percent of trichomes are hazy, and 25 percent have turned amber. 

Amber Trichomes

The final color transformation is cloudy into amber. If a majority of resin glands have turned amber, you've missed the window of peak potency. With that said, your harvest will still contain a spectrum of delicious cannabinoids but expect a milder intoxication than with cloudy trichomes.

When is Indoor Cannabis Ready to Harvest?

Indoor cannabis reaches harvest much more quickly than outdoor crops. Most indoor varieties are ready within three months, but this still varies depending on the strain, indoor environment, and grower preferences. For example, if you are growing in a small space, you may wish to force into flower much sooner than within a regular grow tent. 

Traditionally, indicas reach maturity faster than sativas, although these days hybridization has shortened many sativa-dominant hybrids to be more suitable to an indoor schedule.

You will also want to check out valuable resources like Seed Finder to investigate timelines for specific strains from hundreds of breeders. Most strains information via databases like Seed Finder indicate days to maturity or expectations for the flowering stage. For example, White Widow from Delta 9 Labs requires +/- 63 days in flower.

When is Outdoor Cannabis Ready to Harvest?

Indoor cultivation means you can hit three or more crops a year; if you choose to grow outdoors, you will likely only get one complete season. Outdoor growing relies on seasons, weather conditions, and daily temperature to shift the plant from vegetative into flower. Therefore the exact timing on outdoor crops highly depends on local climate and geography. Depending on these variables, expect a six to nine-month timeframe from start to finish. 

Importantly, if you are growing outdoors, other conditions may influence harvesting. As you begin your daily bud-checks for trichome development in fall, you'll also want to start checking on the weather. Outdoor growing is inherently riskier, and if the forecast predicts upcoming wet weather, you may have to harvest earlier than you want.

Know When to Harvest Milky Trichomes and Bright Red Hairs

In summary, catching your harvest at the pinnacle THC content requires a little knowledge about the strain in general, then daily attention to trichome development in the later weeks of flower. 

Indoor marijuana plants tend to reach harvest within three months, while outdoor growing can take up to nine. You may also notice subtle differences between indica and sativa-dominant varieties. Watch for yellowing fan leaves, bright orange hair development, and, of course, those delicious milky trichomes.


With a little research and a lot of patience, you'll eventually learn the language of your cannabis plants. They tell you in obvious ways, the perfect time to harvest.

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