Still Not Quite Ready for Harvest (pictured below)
Still waiting for at least 40% of the white hairs to darken and curl in; even though some of the pistils are starting to look mature, this plant has much less than 40%, so it's still too early to harvest.
Beginning of Harvest Window (pictured below)
The harvest window opens after at least 40% of the white hairs have darkened and curled in. The plants in the pictures below can definitely be harvested, but they wouldn't be at their maximum size or potency.
Ready for Harvest (pictured below)
Harvest when 50-70% of hairs have darkened for highest levels of THC.
Harvest when 70-90% of hairs have darkened for a more calming,
anti-anxiety effect as some THC turns to the more relaxing CBN.
With some strains, it is much harder to tell when the time is right. Different strains can look different ways at harvest. For example, some strains can keep most of their pistils white even when they're ready to be harvested.
You can get some good information by talking to someone who has grown your strain before, such as the breeder. The breeder or growers who've grown your strain before can often provide extra insight into what to look for at harvest. You can also search online for pictures of what your strain should look like when it's fully ripened.
Next, we're going to go over the 2nd (and MUCH more accurate) method of checking your cannabis plants to see if they're harvest-ready...
2nd Method to Identify Harvest Time: Trichome Method
(the accurate method)
This method tends to be more precise than looking at the pistils of your cannabis plant.
With this method, you look at the glandular stalked trichomes on the buds under a magnifying glass. Trichomes are the the mushroom-looking growths on cannabis that are responsible for it being so popular!
In some places these trichomes are called resin glands. These trichromes are the 'crystals', or 'frosty stuff' you see accumulating on your bud/leaves. They're also what makes weed so 'sticky'.
A bit of random trivia for you: For some reason some cats love the taste of trichomes! They may lick or chew your plants around the leaves or the buds, at the absolute worst time during the flowering marijuana stage. Once they get a taste, you'll have a monster on your hands. So if you have cats, make sure you keep them far away from your marijuana, especially during flowering!
The trichomes you're trying to see look like little mushrooms. You'll also see tiny, clear hair-like trichomes without the mushroom head - these aren't important to potency so you can ignore them. You are only interested in the trichomes that have a little ball on top. This is where a lot of the THC and other good stuff in cannabis is located. Since these are what contribute the most to bud potency, being able to tell when they've reached their highest levels of THC will help you be able to choose the exact right time to harvest.
These trichomes are difficult to see with the naked eye, so you'll need a jeweler's loupe or other way to magnify the image in order to use the "trichome method" for determining harvest time....
Jeweler's loupes are relatively cheap to buy online, or at a hardware or jewelry store.
If you put the loupe right up to your buds, you'll get a better view of the trichomes, letting you better determine their color and shape.
Click the picture to the left for a close-up to see what that looks like.
Although a jeweler's loupe can make trichomes appear bigger, sometimes it's not big enough. I know I end up squinting a lot when I'm trying to use one, but they are a heck of a lot better than nothing!
A digital microscope that takes video works even better than a jeweler's loupe or other magnifers since you get a much clearer pic of the trichomes. Not only can you see the trichomes better, but you can record video of them to look over after the fact. These are still pretty cheap, costing about $40, and they will give you better results than any other method for determining harvest.
Here's an example of a digital microscope in action - these buds are ready to harvest.
We took these videos using the Carson zOrb hooked up to a laptop. So far this seems to be the most accurate way to look at trichomes (and you can make the picture big so you're not squinting through a tiny jeweler's loupe)
Here's a guide breaking down
when to harvest marijuana buds based on color of trichomes.
(note: the trichomes of some strains turn purple or pink instead of amber/gold/yellow)
Note: Guide is based on color of resin glands/ trichomes (you will need a magnifier)
Many of the cannabinoids we enjoy most are produced within these glandular stalked trichomes. This includes THC, CBD, and CBN amongst others.
Summary: Tips & Hints
Here are some general rules about harvesting marijuana based on trichomes and the color of the hairs / pistils.
Want more of an 'in-your-head' effect? Harvest your buds earlier, when only 40% of hairs have darkened and curled in and more than half of the trichomes are part clear/ part milky or mostly cloudy/milky.
For the "strongest" marijuana buds with the most psychoactive effects, and highest levels of THC, harvest when almost all trichomes are cloudy/milky.
For more relaxing, anti-anxiety buds, wait until at least some of the milky / cloudy trichomes have darkened to amber. More amber = more relaxing, though the effects may be somewhat less psychoactive. Remember, curing your buds properly for at least 2 weeks to a month will also give them more of an anti-anxiety effect.
When growing your own marijuana plants, you can certainly sample buds off your plant at different stages to get an idea for what your preferences are. It's okay to cut off pieces at a time!
The hardest part of growing for many new growers is waiting for the right time to harvest.
There is a strong tendency for new growers to harvest the plant early due to excitement.
Unfortunately, this often results in low yields and lower-potency buds.
If you are feeling excited about harvesting your marijuana plant, take branches off the lower part of the plant that look the most done and dry them and check the potency for yourself.
Harvesting the buds in stages (starting off slowly with small batches) can really help abate the excitement.
When in doubt, listen to your gut. Using both methods together will help you pick the best time to harvest, but only YOU know how you want your buds to turn out. This means that even the best methods are just general guidelines. But hopefully, you're now closer to getting your bud the way you want it.