I am working on the Hadspen garden proposal and have a number of technical questions which would help facilitate the schematic design process.

Presently we are investigating a variety of formal ideas that your expertise will help direct. In a broad sense, we are hoping to find the technical limitations of a garden

to manipulate the ground plane, creation of microclimates, and drainage. I have started a list of questions which I anticipate will grow more specific as the process continues.

Hadspen Walled Garden : approx 3,085 sq m = .75 acre = 33,206 sqft The ground plane drops 8.25m from a high point in the west-Northwest, to lowest point in the Southeast corner and is enclosed by a 2.5 m high masonry wall.

1) Microclimates: What is the real impact of the 2.5m high wall to the present garden?

Do the plants immediately adjacent to the wall benefit primarily, or do the influences of the wall extend further into the centre of the garden?

If we create berms, retaining walls, or other undulated ground planes, do you think we will be creating more microclimates within the walled garden that could be advantageous to a gardener? Blocking wind, creating warm air traps, trombe walls?

There is an interest in extending the ‘season’ of the garden. Presently the Pope’s suggest that the existing microclimate provides an additional 3 weeks of seasonable temperature. Are there methods of propagating the microclimate phenomenon through topographic manipulation? Through technically assisted means (i.e. irrigation, materials, etc.)?

2) Planting dimensions What is the maximum angle of repose for the current soil (heavy alkaline clay, I read somewhere)?

Is this limit applicable only to extended (long) slopes, or also to planter beds of 2-3m wide where the slope would be quite short in length?

Ignoring the conveniences provided by a flat level ground to a gardener, what is the steepest grade viable for plants?

Are there commercial available products that one can place under the soil to increase its capacity to resist washing away? (i.e. like the snow guards on a roof) What depth of soil do you consider optimal for the existing kinds of plants (plants common to pleasure gardens)?

Does this depth of soil include water retention or does the substrate have performance requirements aside from drainage? (could the substrate be concrete, clay, gravel?)

What is a standard/optimal planter width? What determines this dimension (maintenance access, exposure to light, visual accessibility, etc.)?

4) What orientation of the ground plane toward the sun is optimal for daylight exposure? (The garden’s slope is presently 7.5° across a 55m distance)

Do you have, or can you recommend a source for, data about wind, rain, temperature, sunshine, or other natural elements specific to the Hadspen garden area? Wind roses, sun charts, etc.

5) Presently most of the work in the garden is done manually with wheelbarrows, shovels, etc. Is there a particular machine amongst garden enthusiasts that we should think about providing special consideration for?

6) Composting: This is something I know very little about. What would be the desirable size and setup for a conventional compost area to serve this size garden? Are there factors about a composting area that we should consider that might challenge the convenience to locating one immediately adjacent to the garden (i.e. odour, pests, etc.)?

7) Drainage: What is the optimal configuration for drainage at the Hadspen site where the slope is constant and relatively steep? Would one want to collect the water and remove it, or have it distributed through the site?

Frost drainage is currently provided by the open gate at the lowest Southeast corner. Can we consider cool air dynamics and fluid dynamics to behave similarly? Would a path that was flanked on either side by inclined planting beds generate a ‘less that optimal’ microclimate because of frost or would it have nearly negligible effect? Suppose the path were 1.5m wide and the flanking planters were 2m wide with the maximum permissible slope.

Thank you for your answers to these questions; your expertise will be of great assistance to the formulation and development of our ideas. Certainly more questions will follow. Additionally, I would welcome any suggestions of authoritative technical resources/handbooks for gardens. If there are projects you think illustrate some of the answers to the questions I am raising, please do not hesitate to mention them.

Emory Smith is the name of our project architect. He was with us for a while, went to Harvard to do a master’s and is coming back to London, at least temporarily, to do this project. He is both academically bright and an excellent designer. He arrives on Monday and we can absorb him on something else, but that is a bit dangerous because people then tend to get stuck and we think he is ideal for this project. It would be better for him to start on this as soon as possible. We could get him to visit the site next week and start digesting the material before you come, so that the first meeting can be more productive. In order to start, what would be very important is to get digital files of the surveys as soon as possible. If you can get somebody to send us the stuff immediately, we can start testing.