What is the Best Time to Harvest Cannabis?

It would be a shame to ruin your previous efforts so sometimes it is better to wait just those extra few days. You will be rewarded for your patience and end up with a much more satisfying product. This article was written to give you some ideas on what to look out for. Let's dive in.

Introduction: Why wait?

The best time to harvest cannabis depends on how you plan ahead. Whether you are growing indoors or outdoors, there are many different circumstances that can affect a plant's life cycle. Harvesting your plants at the right time will determine their effect and flavour, and mainly relies on you.

Many growers, and especially beginners, often get impatient with their grow. Buds can look so inviting as they reach the end of their cycle, and you may be thinking about chopping them early. As tempted as you might be, there are some things you should know first that may help you resist cutting your hard work too early.

Different Strains: The Cycles

As you probably already know, there are lots of strains of cannabis. Different genetics means cannabis plants will grow and develop at different speeds. Flowering cycles range from as low as 6 weeks (indica dominant) to up 15 or 16 weeks (sativa dominant). Choose your strains and check how many weeks of flower they need to mature.

Here we have put together a small list of 8 different strains with their flowering times to give you an idea.

Commercial grows are producing at a fast rate so growers regularly choose strains with short flowering times. Most growers prefer strains that flower in 7 or 8 weeks because they require less maintenance. A flowering time of 8 weeks also means a grower can get 4 or 5 harvests per year depending on their set up.

Some strains, like Durban Poison are ideal for growing outdoors so their harvest time will depend on the seasonal changes. Sativas are often grown outdoors because they can grow so big.

Outdoor plant ready for harvest by Dalemac from Grow Diaries.

Check the schedule for the strains you are growing. You can also connect with other growers to find out how growing your strain went for them.

This will give you an idea of how long it takes to flower but consider that your growing environment can affect the cycle of a plant.

Tip: Whether you are growing indoors or outdoors, it is a good idea to group your plants into their different strains. Labelling the pots with the name and date helps a lot, and you won't forget which plants are which.

Trichomes

The trichomes on the plant are what we normally look at to see if a plant is ready for harvest. The trichomes are very small and can be found covering bud sites and leaves as a plant flowers. They can look like very tiny mushrooms, with a stem and a ball shaped cap.

Trichomes give the plant their stickiness and contain most of the goodness we love about cannabis. The plant's terpenes can be found in the trichomes, and are what gives cannabis it's lovely smell. You will notice how much stronger this gets as the plant develops it's bud.

During flowering, trichomes start to grow in large numbers.

It is strongly recommended that you get yourself a loupe or handheld microscope with a 30-50x zoom so you can take a close look at the trichomes. This is actually really fun and interesting to do because you can clearly see all the details on the surface of the bud. Being able to see the development of these trichomes will help you judge when is the right time to harvest.

You might already be seeing lots of trichomes and be wondering if your plant is ready. If the trichomes on your plant are still clear or look like glass, then your plant may need more time to develop. Give it another few days and check them again. Bear in mind the colour of the trichomes can also depend on the strain so consider the flowering time of your chosen strains as well. 

• If the trichomes are turning a golden/amber colour or going cloudy, your buds are ripe and probably ready to cut.
• Don't wait too long otherwise the THC (Tetrahydrocannabinol) will start to break down.
• When you can see a lot of these trichomes it is a sign the plant is maturing and reaching it's peak.
• Use a microscope with 30-50x zoom or a magnifying glass.

Zooming in with a microscope allows you to clearly see the trichomes.

Tip: You can also use a camera to zoom into the trichomes. It won't be as good as a microscope but if you have a decent camera, even on your phone, you may be surprised at what you are able to see.

Pistils

Another way to tell if your plants are ready is to check the pistils. They give the same signs as the trichomes and will usually turn amber. This can vary from strain to strain, so you may want to check with another grower who has grown the same strains you are growing.

If the pistils are still white and pointing up then you need to wait longer until you see them ripen. Once they start darkening and curling in, you are getting close to harvest day.

Lots of white pistil hairs is a good sign and means a cannabis plant is still developing its flowers.

It's normal that your plant's pistils will change colour first on your top buds as these usually mature before buds lower down due to being closer to the light source. You want to wait until at least 50% of the pistils have changed colour.

If you notice your plants have stopped producing pistils and 60-70% look ripe, think about harvesting soon. This will be more or less the optimum range if you are looking to maximise THC content.

A cannabis plant is nearly ready for harvest once its pistils are brown and curling inwards.

This method of checking is useful if you don't have a microscope to zoom in on the trichomes. However, check the trichomes if you can, because some strains have different coloured pistils or might not change colour when they are ready to harvest. 

This grower is in week 6 of flowering and should wait a couple more weeks until harvest. Notice how only about half the pistils have changed colour.

H$L GROWS

Best time to Harvest Outdoor Cannabis

Growing outdoors means your plants are subject to exterior conditions that can affect the length of the flowering cycle. Much of it depends on the region you live in and the climate you experience there.

You will learn more about the conditions of your area with every grow you do, so don't give up! Weather can be unpredictable but can also do wonders for your garden.

Outdoor plants can be very rewarding but also require your attention so you choose the best day to harvest.

The hours a plant receives under the sun can change how long it will need to spend in flower before it's ready to harvest. Outdoors, you have less control over the plant's growth and the climate in your region will also affect how flowers mature. Timing is very important so you should be checking your plants daily towards the end of the flowering cycle. 

You need to make sure you harvest your crop before the first frost hits. Plant matter will start to mold or rot as temperatures decrease below 15°c (59°F). If you plant too late into the spring, your plants may not grow big and strong enough before flowering begins, in the end leaving you with smaller harvests.  

5 tips to get the best harvest time outdoors:

• Choose strains that suit your growing environment.
• Germinate seeds inside at the end of winter/early spring.
• Check the sun cycles in your region before planting.
• Sow outside when temperatures don't drop below 15°c.
• Harvest before first winter frost.

When leaves start to turn yellow a plant is showing signs of maturity. This is the beginning of the harvesting phase as the plant begins to die and use up it's remaining store of nutrients. This is not to be confused for early yellow/browning of leaves, which could be related to a deficiency.

Normally growers will harvest their outdoor plants from mid September to mid November. In the northern hemisphere, this is as the autumn equinox arrives and the days start to become shorter again. After you notice leaf yellowing, you can tell if they are ready by checking the pistils and trichomes, as we mentioned earlier. 

Best time to Harvest Indoor Cannabis

Growing indoors gives you much more of a clear idea as to when you will be harvesting. Having full control over the amount of light means you know more or less when your plants will be ready.

Plants that receive the correct amount of light will flower in approximately the same amount of time stated by the breeder, depending on conditions. Remember that there are many variables that can affect your plant's growth, so it's best to harvest when the plants look ready.

Most indoor strains are feminized, meaning they will flower in a set amount of time after the light hours are dropped to 12. Because you are in control of the light hours you have the possibility to experiment more freely with different harvest cycles.

Indica dominant strains flower much faster than sativas. They flower in about 7-8 weeks after the light schedule is flipped to 12/12. So long as you made a note of when you put them into flower you will know when to start flushing in preparation for harvest day.

It is common for the top parts of a plant to ripen before lower parts because they are closer to the light. One thing some growers like to do is to cut off the top buds and leave lower buds on for a few more days. The plant will push whatever energy it has left into those remaining buds and they will also have more light on them. 

GreenMachine from Grow Diaries shows off his trichome covered plants 2 weeks before harvest.

Harvesting your plants in the morning is the best. Chemical activity in the plant is at it's highest in the first couple of hours of the day. You also won't disturb other plants in your grow room by working during the dark hours.

Tip: Writing up a calendar to know exactly how many weeks your plants have been in flower is a great way to remember when you will need to harvest your plants. It is also helpful to keep a diary so you can keep track of each plant or strain you have.

Effect vs Flavour

There is a common discrepancy between growers about when is the perfect time to harvest. Some believe that harvesting earlier gives you a slightly sweeter taste with just enough potency. Others might prefer trying to harvest when they can get maximum psychoactive effect. Then there's those that want to get 'stoned'.

In the end it all comes down to personal preference. We recommend you stick with one strain through multiple grows so you can discover what works best for you.

Once the plant passes maturity, THC compounds begin to break down. As the THC degrades, it converts into CBN (cannabinol). CBN rich weed will produce a harsher smoke, but some growers prefer more of a body high and so will cut their plants towards the end of the harvesting window. 

Trichomes are what contain most of cannabis' unique flavour.

The effect will depend on the strain, and whether it is more indica dominant or sativa dominant. To achieve the most psychoactive effect you will want to concentrate on harvesting when your plant is at peak THC level.

This chart is only a general look at how different percentages of brown pistils can indicate potency and flavour. We advise you to try out different harvesting times and see what you like the most!

Harvesting Early

If your crop is failing for whatever reason, you may need to harvest early. This is a decision you will have to make based on the problems you are facing. It is never a nice thing to have to scrap all your plants but sometimes it is the best solution.

Choosing the right harvest day will determine the quality of your weed.

Bug infestations or fungus in your garden can spread quickly, so to avoid things getting worse it is sometimes a smart idea to accept the loss and start again. You do not want these pests to multiply because it could become a constant problem in your growing environment.

Tip: Pesticides and fungicides are not recommended during flowering as they can massively affect the taste of the final product if used too late in the cycle. 

Conclusion

After you have spent so much time caring for your plants, it would be a shame to get impatient and harvest them early. However, feel free to experiment with this as you may find new flavours or highs in your favourite strains. You can even cut off small buds at different stages during harvest to test out what you like best.

Don't leave your plants for too long after the harvest window has begun, otherwise your weed won't be as potent and will start to lose it's aromatic flavour. We'd love to hear what you think about harvesting times, so drop us a comment below!

External references

Cannabis, Cannabinoids, and Sleep: a Review of the Literature. Current Psychiatry Reports. - Babson, Kimberly & Sottile, James & Morabito, Danielle. (2017) 

Cannabis Species. - B. Singh, Ram Avtar Sharma. (2020)

Cannabinoid synthesis and accumulation in glandular trichomes of Cannabis sativa. Journal of Acupuncture and Meridian Studies. - Kim, Eun. (2020) 

Hot Summers in the Northern Hemisphere. Geophysical Research Letters. - Zheng, Jiayu & Wang, Chunzai. (2019) 

This article was updated August 2020.