Water, weed, good dirt is necessary, um that's about it.
Today would have been my grandma's 86th birthday and I've been thinking about her lately. She had an amazing green thumb. Her house was always full of plants and she could revive almost anything. Once she grew a plant from a cutting that overtook her entire living room. She called the LDS Church office building to see if she could donate it to them. They asked "Well, is the plant healthy?" "Yes, that's the problem." They had to remove her double doors and carry the thing out on a large plank of wood to get it out of her house. Then they hauled it away on a flatbed truck. I'm sure that she had lots of botany secrets, but the one I remember was hair. Whenever she cut her kids hair she saved the trimmings and buried them in the dirt of her pots. Hair is full of protein and nutrients that will be eventually broken down by bacteria in soil and made available for absorption by the plants. So a few days ago when my mother-in-law trimmed my son's hair, I saved the hair in my new compost bucket. In the next few weeks I plan on planting a tree in my backyard. Hopefully the fruit peels and hair clippings will help it out.