The colour of the plants trichomes can give a good indication of the amount of THC and CBD and thus the optimum time to harvest. It is recommended to use a jeweller's loupe or USB microscope to observe the colour. Most growers harvest their cultivar when a third of the trichomes have turned amber, by this time most of the trichomes are full of THC. Trichomes turn amber when the THC has turned into CBD. There are also other indicators of maturity such as the color of the stigma, the size of the calyx, and water intake which should lower during flowering.
Trimming
Trimming is the process of removing fan leaves and sugar leaves from the buds of the plant. Trimming before drying is referred to as a wet trim and after drying is referred to as a dry trim. Leaves removed from the buds during trimming can be used to make edibles.
Drying
Buds are generally hung to dry in a warm dry location after trimming. The temperature and humidity of the drying space will affect how long the buds take to dry. In the process of drying biological processes continue inside of the buds and complex carbohydrates and chlorophyll is converted into simple carbohydrates such as glucose. Drying slowly is preferable as it ensures the maximum breakdown of sugars and also that the inside of the bud is as dry as the outside. Buds should be left to dry until the stems bend but are somewhat firm when pressure is applied, then they should be stored in air-tight glass jars for curing. If the jars humidity is over 70%, the buds are not yet dry enough to be stored for curing.
Note: It is not recommended to smoke under-dried weed as it can induce a headache.
Drying setup examples
Curing
Curing is an essential part of producing marijuana that is smooth to smoke. The quality of the bud can continue to improve for a duration of 2 months to a year or until the humidity of the bud reaches below 55%. Once buds are dried they should be stored in an air-tight container preferably glass and "burped" (left open for 15 minutes) every day for a week or two, and then burped approximately once a week. The key objective of curing the buds is to slowly lower their moisture content for as long as possible. Inside of a jar, the moisture content of the buds can be measured by using a hygrometer. Curing should take place between 70-55% RH.
62% RH is the recommended humidity for long term storage