There are many types or strains of marijuana, however they basically fit into two categories; Indica and Sativa. Breeders will often cross strains to change the growing or properties of the original.
As a rule of thumb, generally Indicas tend to be shorter, stockier plants with smaller, denser and smellier buds. Indicas also flower much faster than Sativas, usually with a 6-9 week flowering period. Sativas will grow taller and generally much bigger. Buds will also be bigger but less dense. Sativa buds will also be less smelly and take longer to flower than Indicas, usually 9-10 weeks.
Choosing types of marijuana for a garden will depend on many factors, not least what you expect of the end product. Marijuana strains are often a cross of Sativa and Indica to give properties of each i.e. to make certain Sativa smaller and more potent, or an Indica larger and with bigger buds. As far as the high is concerned, Sativas will tend to produce more of a cerebral, energetic or giggly high, while Indicas produce more of a body stoned, known to enhance physical aspects such as sound and taste and can also have a relaxing effect.
Below are pictures of some of the most popular strains or types of marijuana, followed by an A-Z of strains.