Banana circles are a popular design element in tropical permaculture – for good reason! A banana circle is essentially a concave ditch filled with organic material, surrounded by a mound that is planted with a variety of high-nutrient demanding plants. By adding banana circles to your tropical garden, you basically add pockets of fertility to your land, which act as a sink for organic wastes, as a food production system, as a habitat for insects, and as a fertility hub. You can even direct moderate amounts of grey water into them (for example from your kitchen sink), which will keep them nice and moist.
Banana circles are easy to set up, require hardly any care, and help to keep cycling nutrients in the tropics. Also, they provide a simple solution to a common cultural habit in tropical countries: the clearing of the ground as not to provide hiding space for poisonous animals such as snakes and spiders. This is common practice all over Indonesia and usually all the leaf litter and everything that falls to the ground is burned. What a waste of valuable nutrients! With banana circles in place, we can still keep the ground clear, but ensure that nutrients are cycled back into the system. So let’s dive right into the construction.
Although the name suggests that banana plants are an integral part of this element, you can actually plant any nutrient-demanding tropical plant instead of bananas – such as papaya, coconut palm trees, or passion fruit vines on a pole construction.
Banana Circle Layout
As I said, it’s pretty straight forward. To help you grasp the concept I’ve nicked these graphics off my teacher Doug Crouch’s article on Banana Circles and they’re pretty much self explanatory. Make sure to wisely choose your location, applying the permaculture design principles.
Digging your banana circle
So get your hoe, spade, or whatever tool you prefer ready and let’s get going! Measuring and staking off the areas for the ditch and mound makes things a lot easier. I just put a stake wherever I wanted the middle of my banana circle to be, attached a string to it, measured off 1m and used it to stake off the circle around it – with a radius of 1m you get a diameter of 2m for your ditch. Repeat the process, this time with your string roughly 1.65m long, and you’ve got the diameter of your mound. Obviously you can also go for other dimensions, but I found the ones provided by Doug to be quite good in terms of their ratio of ditch and mound size.
Now you can start digging out the ditch, piling the earth all around you to create the mound as you go. Make sure the bottom of your ditch is concave (as in Doug’s graphic) and the composting material you pile up later on is convex to avoid creating a mosquito-breeding-paradise.
Planting your banana circle
Once you’re done digging you can immediately start planting in all your plants and filling up the ditch with organic material. I would also recommend to immediately cover the mound with a thick layer of mulch to prevent nutrient loss and weeds from coming through. Alternatively you could sow a fast-growing cover crop such a mung beans (soak them overnight, then spread them all over the mound and slightly rake them in). Once your lemon grass has grown a little, weeds shouldn’t be a problem anymore.
Most of the plants you can easily obtain from cuttings or root division. With lemon grass, it’s enough to stick one bulb in the ground and it’ll quickly grow. Cassava, taro, and sweet potato can be grown either from the root (just stick them into the ground) or from cuttings (also, just stick them into the ground). The tropics make things very easy in that respect! For your bananas you simply transplant the “babies” of an existing banana plant – cautiously dig them up and separate them from the bulb.
Now all you gotta do is to throw in some organic matter from time to time, watch your plants grow, and harvest a tropical abundance of fruits and roots.