Saturday, 21 December 2013

Practical solution for growing plants and vegetables on the roof

It's been quite a few months since I started extensive research about roof gardens. They bring a lot of advantages, both visually and practically. As being energy efficient (heat/cold insulation), they can be quite useful especially if they include vegetables and fruits.

One thing for certain, this was not going to be an easy task. There are structural considerations to take care of and the initial investment can become quite expensive. Therefore I decided that in order to have a roof garden I had to settle for something in between a proper roof garden and small pots.

Raised beds were my choice of solution. They give a lot of flexibility in what one could grow in them if they are good sized ones. Good sized does not necessarily mean that the bigger and deep they are the bigger the plants or vegetables grow. I also did not want my raised beds to be permanently fixed. If I need to have access to the whole roof I would need to move them.

I came up with the following sketch. A wooden frame holding a few containers side by side so that it looked like a continuous raised bed. It would be easy to move it out of the way if need be.

From my research I found out that a soil depth of ten to twelve inches will give very good results. The best containers would be those green field crates that they carry fruit and vegetables in. There are two common types of these containers. The deep ones were the perfect choice as their height is around the twelve inches mark.

Sourcing the crates was not difficult. One from our green grocer nearby, the other three from one of my colleagues at work. I got them for €6 each and in very good condition as well.

The important thing to remember is that the crates have to have a lot of holes so that the water drains out easily, especially when it is raining very heavily. These particular crates did not have any holes at the bottom so I drilled a lot of them at regular intervals. As the holes on the sides of the crate were too big I purchased a plastic net with smaller holes to cover the inside of the crates. Unbelievably the cost of this net was not so cheap as expected, but it was a one time investment so I went ahead with my plans.

After much consideration both me and my wife decided that for this Winter we should only try one crate on the roof to see if this will work, just in case it needs tweaking. It would be a disappointment if nothing grows or worse still, the cold months kill the plants. However if it does work, in Summer I will prepare the rest of the crates and build the frame.

Just before Winter my wife had planted a few cherry tomato seeds and peppers in small pots which she kept under very careful monitoring with the first few days inside, the next in the balcony. A few weeks ago these were carefully transferred to the compost filled crate. We made sure that the roots were not disturbed during the transfer.

We had a couple of storms already in Malta with very heavy rain and cold winds. Every time we thought that all our plants on the roof were destroyed, however they did survive and kept on growing without any noticeable problems.

We do not go on the roof very often now and yesterday we went up on the roof to check up on them. As you can see from the photos below, they are still alive and well, and that is just from ten inches deep of compost. On a closer inspection in the second photo, it seems that it is not just leaves that are growing.