Here are the ones we know most about: THC stands for “Tetrahydrocannabinol,” which is a fancy word to describe the main cannabinoid in cannabis that produces much of the euphoria and other mental effects. For medical marijuana patients, THC seems to be one of the most important cannabinoids when it comes to reducing pain. CBD stands for Cannabidiol, a non-psychotropic cannabinoid that has recently been in the spotlight for its medical effects in fighting seizures. It does not cause the psychoactive effects of THC, and may have lots of other beneficial effects for medical marijuana patients.
CBN stands for Cannabinol, another known cannabinoid. CBN causes milder mental effects than THC, and more of a body relaxation effect. CBN levels do not have a lot to do with strain – they are raised by harvesting buds later. When shopping around for cannabis strains, you’ll often be able to get information from the breeder about THC and CBD levels. Avoid “dabs” or waxes as they can contain contaminants that aren’t appropriate in a medical setting. When shopping around for strains, many breeders will give you information about the THC and CBD levels of the buds produced by this strain of cannabis.
If they can’t give you specific numbers, I recommend avoiding that breeder if you’re a medical cannabis patient. Psychedelic, more “trippy” effects, but can cause anxiety for some people. High THC, Medium CBN (by harvesting plants later, especially effective on indica strains) “Couchlock” (very relaxed, almost sedative effects) Appearance & Smell of Buds. The following factors vary quite a bit from strain to strain, and also change due to different growing methods. Varies by strain & growing methods: Appearance – Bud Structure, Color, Density. The buds of different strains look different from each other. Some buds come in green, orange, purple or pink hues. Some tend to be light and airy, while others (often indicas) tend to grow very tight, dense buds. Different strains also produce different tastes or smells in their buds. Appearance and taste/smell are parts of the whole growing experience. If the characteristics of the bud appearance or taste/smell is the most important to you, then it's important to determine what you're looking for so you can choose the right strains to fulfill your needs. There are many breeders that specialize in pretty, fragrant and colorful strains. There are many strains that actually have "purple" or "pink" in the name. The pictures and information given by breeders will help you find the exact strain you're looking for! Note: I believe it's important to pay attention to bud effects as well as the appearance or taste/smell of a strain. Even if you're growing a particular strain for its looks or taste/smell, sometimes the result doesn't come out as expected due to a different environment, grow lights, nutrients, or just plain genetic variation. But if you get a strain with the effects you're looking for, you know you'll be happy at harvest time! Your growing methods have more of an impact on the appearance of your bud than the effects (though it affects both!). For many growers, the potency and effects of the bud are the #1 thing you care about. We already talked about sativa vs indica, and medical vs non-medical strains, but there's still a lot more to potency and effects. It's also important to remember that the time you harvest and how you dry/cure your buds after harvest have a huge effect on the final potency and bud effects. The time you harvest can make the difference between speedy, "mental" or "body" effects. The dry/cure adds significantly to the perceived potency of your buds if done right, and without a good dry/cure buds are not as enjoyable and can give you a headache. But strain also has a huge effect – you can't grow buds that are better than their genetics, no matter how great a grower you are!
Here's what you need to remember about potency when shopping for strains. THC & CBD only tell part of the story – I've had strains with 15% THC blow the socks off a strain with 25% THC, at least as far as the potency I experienced.
Although THC and CBD numbers do have a big effect, once you're above 15% THC or so the results seem to become a lot more subjective. You can have 20% THC cannabis that is almost too strong, and other 20% THC cannabis that only as a small relaxing effect. There are other cannabinoids in cannabis besides THC, and they can moderate and alter the effects you feel, so don't get too caught up on the numbers. Even if you're looking for the strongest bud possible, I'd stay open to what people say about the effects, and take the advertised THC percentages with a grain of salt. Mental vs Physical – One of the major differences between strains is whether the effects hit you more mentally or more physically.