If you honestly want to grow high quality Cannabis, you first need to get fine seeds and obtain them correctly from an online seed bank or a reputable Cannabis dispensary.
Typically I will say though, there will be a much better variety of strains if you honestly choose to look at online seed banks.
You can find virtually any strain online for sale, though it is true that some strains are still always harder to find than others, then some strains are so popular that you almost always will see that these strains are commonly sold out. You can try to get either proper seeds, or seeds that are feminized from your source, then most people care about to go with feminized seeds quite often because the females are the plants that create the buds. If you guess anything about Cannabis, it is the bud that you are looking for as this is the THC, or medicine of the plant. The male plants will only produce pollen. If you ever wish to produce more seeds, you might want to just get regular cheap Cannabis seeds, but this way you won’t guess how several females you other will get compared to males. With feminized seeds, you are simply guaranteed all female plants as well as you don’t have to worry about sorting out and killing the male plants. You can also learn how to clone which is a highly essential skill to learn as a Cannabis grower. When you learn to clone, all of a sudden you can effectively make as several plants from a single plant as you ever want. If you guess how to clone, you never will have to buy that particular strain again if you keep it alive through the entire cloning process. And with plants that are never pollinated, well, that’s helpful because, you have what is called sensimilla which produces no viable seeds as well as has the highest quality cannabis buds.