If you want to find out about growing delicious, organic veg on your balcony or roof terrace, this is the site you've been looking for. My name is Wendy Shillam. My aim is to provide practical, accurate, tried and tested growing advice for anyone wishing to grow vegetables in containers, beautifully. Over the past three years I have been growing on a fifth floor flat roof in Central London. This site documents the development of that garden and provides seasonal advice and comment. I am a writer, so my blogs will I hope provide a pleasurable read, whether you are sitting in the armchair dreaming(go to the BLOG pages), or up to your elbows in compost and you need immediate answers(go to the QandA, or click on the KNOWHOW or PLANT OF THE MONTH links at the side of this article.
I will be offering some answers of my own, based on my very specialised knowledge and experience. And I hope others out there will contribute as much with the answers as with the questions.
My experimental plot is a flat roof above my house in central London. The plot is approximately 17’x19’ or 5m x 6m and situated on the fifth floor. The quality of light is good up here, and there is some protection from winds. The terrace is walled on the south and north side and open on the east and west side. I have fixed a trellis fence on the east side to reduce the chilling northeast winds. However, the prevailing winds come from the west side, which is still open because that is also where the afternoon sun comes from!
Where the beds are adjacent to walls I have constructed various trellises. I use freestanding wigwams as well. In 2013 I added three new trellises that create an arboured entrance to the plot.Once space has been taken out for the staircase access, chimney-breasts, the shed and a roof-light, I am reduced to five large raised beds, which each hold about six inches (150mm) depth of soil. The beds vary slightly in size, but are each about 6’ x 2’ or 1800mm x 600mm. Wider raised beds are sometimes recommended, but I find this size quite wide enough for reaching into. I never need to stand on the beds, but I do dig them over after harvesting.
Scattered around the formal raised beds, I have a placed collection of pots. These containers provide a deeper growing medium for plants like potatoes and carrots, as well as containing rampant plants, like mint, in check. A lime tree, also in a pot, can be moved inside during the winter.
In the southern alcove, between two chimney-breasts there is a seat, and an arbour, which provides a summer dining area and doubles as a planting bench for over wintering semi-tender pot-plants. It is a great location for hardening off in spring.
In 2011 I installed a timber framed grow-house, which I have located against one of the south-west facing brick walls. This contains salads and over wintering plants during the cold season and is used for tomatoes and peppers during the summer months. It has double skinned polycarbonate panels, which give an extra layer of protection against frost in the winter, but not quite so much light in the hot season. The back panel has been removed, so that plants inside can take advantage of the storage heater effect of the brick wall. This aspect is very sunny and I have to shade the grow-house in summer. The roof is fitted with an automatic venting device.
The whole roof top veg plot is fitted with a watering system which will automatically water pretty well every crop.
Between the beds are square timber decking panels, which mean that if I decide to change the layout in the future, re-arrangements will be relatively simple. The substrate is heavy-duty asphalt.Under the northern wall a large timber cabin trunk contains my compost bin. I compost as much kitchen waste and vegetable waste as possible.
As well as this I have a south-west facing window-sill on the floor below, in my studio under the roof light. Here I over winter tender plants, grow salads and have a nursery for seedlings.