Breeding can be performed in the Breeding Lab when you have 2 epic buds: One bud is the mother and the other used as the father. Epic buds are dropped randomly during harvesting and also automatically when a perfect health (mastery) is achieved. Epic buds take up space and are stored in your warehouse. Breeding strains in the lab can yield 2 results:

Each time you breed two strains you have a chance to improve one trait of the mother strain. The green area shows you the minimum and maximum range for how many points your strain can get for that quality, depending on where the marker lands. If you land on the “Bonus” category, then no matter which quality you land on, it'll get maxed out.

To summarize, it's like the birds and bees.
Step 1: Select 1 mother strain
Step 2: Select 1 father strain.
Step 3: Breed them together. Watch the magic.

Result: The child has the same traits as the mom but with the bonuses of dad

Each strain has a maximum benefit it can provide for each trait. So you have to use a mix of strains to level up your quality. i.e You can't keep using Afghani over and over to level up your strain. At the higher levels you will need all 9 strains to level up!

Legendary buds are the highest quality epic bud you can possibly get. You can only find them or purchase them. They have higher average rewards in ALL 4 traits. They are unique in this way.

All strains have both Potency and Aroma.

They also have either Pain or Mood, not all 4.

Usually Indicas have a more physical effect and Sativas mood enhancers. This is NOT always the case, but usually. Hybrids are a mix, depending on their parents. This is because the THC : CBD Ratio.

Generally:

And their quality profiles are made of:

Higher quality strains! Higher quality fathers will give more bonuses in the lab and higher quality strains will give you more money every quality level!