Here are some harvest notes (not written by me) which you will find useful. To see all the images you need click on the links.
When to harvest
Length of flowering is strain dependant, and even then you can't be sure that the seeds will do what they say on the pack. Any reputable breeder will give guidelines as to the length of time that the strain will take to mature. Most Indica dominant strains mature in 8 to 9 weeks as opposed to Sativas which can take anywhere from 13 or more.
As cannabis matures; the flowers - 'calyxes' - swell and grow. Pistils wither and brown but are overtaken by new growth which in turn does the same. Peak maturity is reached when about 90% of the plant calyxes are fully swollen as well as over 80%-90% of the plants pistils being browned with little in the way of new growth.
The following example shows the progress of a flowering plant from day 50 to day 71. Shown in order from left to right.
Notice the lack of new growth (white pistils) in the last two pictures. Lower sections of the plant may not mature at the same rate as higher sections and the entire plant should be taken into consideration when judging if it's ripe for harvest.
Click here for image
Once a grower is able to determine if a plant is ready to be harvested they can use additional methods to determine if it's ready to their taste. This is done by looking at the colour of the trichomes (trichs). Trichome FAQ here by OT1 and here
Trichome colouring
Summed up best by VRG and oldtimer1:
If you have a pocket microscope, or jewellers loupe, you can examine the trichomes (trichs). They start out as just little sticks, and as your bud ripens they grow bobbles on the tops of those sticks. As soon as your trichs have bobbles on, and appear to be ready to burst, you can harvest.
If you leave them on, and keep an eye on the trichs with your magnifier, you can taylor the stone to what you require. They will firstly go a milky white colour, this is the process of THC degrading to CBN, THC gives you the heady "up" high, whereas the CBN gives you the body stone. Going on the pistils, gives you a rough idea of when to chop, but if you get a magnifier, you can chop different buds, at different stages to see what you like the best
Most people chop when the trichs are mainly milky white. If you leave them a bit longer, you will see the trichs turn an amber colour, this is when the buds are at their most potent in terms of couch-lock, and is the best time to harvest if the smoke is to be used for medi purposes.
- VRG
High psychoactive varieties produce clear or transparent capitate heads then they turn transparent amber then slowly oxidise to brown, none translucent. This type is most psychoactive at the early amber translucent stage.
Most varieties do not have a translucent amber stage. What you get is transparent then the milky none translucent that develops over time to the oxidised none translucent brown stage. This type is most psychoactive at the early milky stage.
- oldtimer1
A quick note about psychoactivity by oldtimer1
The thing about amber trichomes, is that true amber trichomes only develop in some phenotypes and only with very high potency types!
The way to define it, is that high potency or should I say the type of plant that develops what I call complex psychoactivity, only develop with clear trichome stages, they go from glass clear to very light yellow to amber to red amber as they develop. The onset of the first red amber just showing is when the potency is at its peak.
At all these stages the trichomes are crystal clear like cut jewels! Its only as they start to degrade that they start to go brown and start to cloud ie: become none translucent this finally degrades to a dark muddy colour.
Types that go from glass clear to milky [like frosted glass]. With this type when you get 40 to 60% milky trichomes, new thc production is being produced at a lower rate than it is slowly degrading, this is the most psychoactive point for this type or variety, it will never produce true amber, instead when you get the oxidised thc starting to show, which is more of an amber brown but cloudy. With this type of var as soon as brown trichomes start appearing you know thc production is way over the top and declining rapidly, at this stage psychoactivity is also declining and the effect becomes more and more narcotic. You see this much more with genes that come from hash making type genetics or so called indicas. Its the same thing as fresh lightly pressed hash has a nice medium honey coloured look, but this very quickly starts to darken, becomes brown then black over time as the surface thc oil oxidises.
Real Amber trichomes only happen on a very few varieties (mainly sativa dominant), the order is clear, clear slightly pale yellow, ie [going amber], to clear red amber. [at all stages they remain jewel clear]
With most varieties (indica dominant) you get clear trichomes then slightly cloudy finally milky.
What happens to both types (sativa and indica) is that eventually both milky and amber trichomes will finally degrade to brown, people often confuse this brown with amber, true amber trichome types remain crystal clear until they finally degrade, they are not the same, the final brown is cloudy/muddy in both types, when trichomes are getting to this stage potency is declining rapidly and the buds well over the top.
With sativa dom’s time means little, as soon as you see the first sign of trichome changes ie milky/clear straw, you start cutting a bud every week, then choose the stone you like best, sats take longer to mature especially real amber types, also longer to degrade to the brown oxidised stage.
Pictures of Trichomes
Some pictures of trichome maturation courtesy of Tricky knome and OT1. Shown here are pictures of trichomes which have turned milky in colour.
Click on:
this
this
and
this link for images.
Few shots of trichomes ready for harvest. Shot on the left is of an indica dominant strain. Shot on the right is a sativa variety:
Click
here for image.
And
here for second image.
Finally you can clearly see the amber coloured trichomes on this leaf. This is about a month over ripe.
Click
here for image.
If you're having problems getting hold of a loupe try ebay You're looking for at least a x10 and at the most a x30.
