Bananas begin their growth process underground, as a corm. A corm is a bulbous underground tuber that essentially acts as an underground stem. Bananas propagate most easily through rhizomes, underground stems or roots that grow outward to form new corms.
From the corm stage, bananas shoot stems out from underground quickly, either growing through old growth and then past it or growing alone with no protective structure surrounding them. These stems quickly grow offshoot stems, which grow offshoot stems in turn. It is best to leave only three stems growing as this will encourage the plant to concentrate on fruit growth later. While you can still easily prune off branches, do so to encourage this growth.
After the banana plant has grown 6 to 8 feet, it will begin to form leaves. This leaf growth will quickly multiply and also, by virtue of more photosynthetic processes occurring, encourage stem growth to occur more rapidly.
Some banana plants take two years to form fruit, while others do so in their first year. This process begins with the formation of the flowers, which appear in the form of a large purple bulb-shaped structure hanging down from the leaves. This purple bud will produce flowers which open up one at a time to encourage pollination. About nine months after the initial growth of the banana plant, green fingers will grow along the stem of the flower, which will begin to grow upward and take the familiar shape of a banana fruit.
Banana fruit should be picked when it looks full and juicy, but still green. It is best ripened off of the vine. After the banana plant has developed mature fruit, it will begin to die back. This is part of the banana's normal growth process. Once it begins to die, it is best to cut it back to 2 or 3 feet in height. The following year the banana will grow again from the seedling stage. In early spring, new stem growth will appear where the plant was cut off the previous season, and the process will begin anew.