For our garden plan, we have planned on using an overall irrigation strategy called sub-irrigated planters. I’ve briefly mentioned what these are in the first post, but I’d like to further explain what these planters are and why we’ve chosen to use them.
Here is a diagram from www.insideurbangreen.com that shows each component of the system and how it functions:
The planters don’t have to be two buckets, it can be one closed container. Here’s an overhead view of a bin style planter, very similar to the ones we will be using. This one uses almost entirely recycled parts, as we hope to do:
For this version, all you do is cut the bottoms off of water bottles and stack them to make the fill tube, poke holes in the milk jugs, and the part that was not shown here, cut larger slots on the bottom of the milk jugs to allow for water to pass between them. They’re incredibly easy to construct, and I can tell you first hand from my personal experience with them so far, they’re incredibly easy to work with. We set up two planters on May 29th, and have only had to water them once or twice so far. Any time I have checked the soil moisture, it’s always wet, but never too wet. Most importantly, the plants look really healthy so far.
There are a number of reasons we have chosen this method in particular.
The first reason is because none of us are engineers or roofers, and we are worried about the condition of the roof membrane, not wanting to damage it (more than it already is). We would also like to be able to have the freedom to play with the layout and architecture of the garden pretty easily and frequently. Because the planters are in individual plastic bins, and because the bins have curved edges, and are relatively light, both of these needs will be met, making the garden’s layout very flexible and modular, and having a very light and minimal impact on the roof membrane.
Another big reason we’ve chose this method is because we don’t have the money to spend on a complicated and expensive green roof system, and in the same vein, we would like all of our methods to be as accessible to the as many people as possible, both in terms of cost and availability of materials. This means we would like to use as many cheap and easy to find components as we can, and where possible, as many recycled and re-purposed components as possible. This system meets these needs because they can be built with a variety of cheap, recycled, and easily found components such as plastic bins, buckets, plastic bottles, milk jugs, old plant flats, and many other things if you use your imagination.
The final reason we’ve decided to go with sub-irrigation is because we would like to make our garden as self-sustaining as possible, requiring the least amount of labor and outside inputs as possible. Sub-irrigation is able to meet this need because we will be able to integrate a rain barrel system that uses rain water catchment, and connect it to the bins, which will then all be connected to each other in a fully integrated system. This system will be made possible with a solar powered water pump that will pump the water from our backyard to the roof, and will also include a timer, making it a “set it and forget it” way of ensuring our garden’s health.
So you don’t have to spend a ton of money or devote many hours a week caring for an urban garden. If you know the right system (which you do now!), you can have fresh vegetables on your roof or balcony for very little money and effort!!