The "banana circle" is a cool concept taught in permaculture classes, and here I am in front of ours.
There are lots of advantages to planting this way, including convenient "waste" disposal and natural fertilization.
The messy-looking dead leaves from the banana "trees" and other plants around the circle are conveniently tossed into the center (a compost pit). There, they break down and add valuable organic fertilizer to the soil, eventually creating something similar to "terra preta," a highly-fertile soil prized in Latin America for centuries.
So, here are the steps to creating your own banana circle:
1. Pick a spot that gets sunlight for several hours a day, and that does not flood (although water directed to drain into the hole in the middle of the circle can be beneficial for the plants, as long as it doesn't saturate them--their roots need water but cannot always or frequently be sitting in it, because they'll rot).
2. Dig a hole about a meter deep and two meters wide. Use the dirt from the center to make a ring around the edges. Then, if you want, you can line the hole with old cardboard like we did, wetting it with a hose or watering can as you go.
3. Then, if you have it, add some organic garden soil and composted cow manure around the edges. Also, in the center, throw any "compostable" stuff you may have at the time (basically, plant or plant-derived material that will decompose).
4. You can add further layers of wet cardboard, or even paper, as we did. Then, plant your banana plants in openings you've left in the cardboard mulch layer.
5. After you've put in the banana plants, add a thick layer of organic mulch on top, from the outside edges of the circle into the edge of the pit. We used crushed palmetto litter, since our property has lots of saw palmettos, which accumulate dead leaves that can easily be crumbled up into a thin, easily-decomposable mulch. But you can use whatever you have access to, including old sticks, straw, uncontaminated grass clippings (I think), leaves of all kinds, etc. (I would avoid store-bought bark mulch, though, since in my experience it tends to decompose into sort of an impermeable mat instead of the crumbly soil you're trying to create.) The object of this mulch is to shade the soil, hold in moisture, create food for soil organisms, and further enrich the soil as it breaks down.
6. Water the circle as needed, to keep it from drying out. Keep throwing dead leaves and other yard compost into the center. And add some composted cow manure or other organic fertilizer around the edges periodically, also tossing some into the middle. Like us, you can even add other species of plants in-between and in the understorey, like papayas, gingers, Stevia, Mexican sunflower (a nitrogen fixer and "green manure" provider) and so forth. Then just watch everything grow!
Oh, by the way, it took about three years for our banana circle to grow from the original construction photos to the shot of me in front of it at the top of this article (taken by my terrific wife, Donna).
