Another post which is not about software! I’ve recently, finally, finished reworking my garden, and here’s a brief writeup of what happened. It includes some ideas for low-embodied energy and ecologically friendly garden design.
The original garden
This house is on a hill. The original garden was a set of three concrete slabbed terraces going down the hill, with some wooden decking on the top terrace. There was a block paved path ramping down the garden, separating the decking from a sloping grass lawn. There were very few plants which weren’t grass or a few pots.
Problems with this included:
- Decking was rotten
- Lower terrace served no purpose and was devoid of life
- There was very little biodiversity in the garden, and no space to grow anything
- Steps in the path had been installed with uneven heights and that was surprisingly annoying
- Get rid of the decking because it’s rotten
- Remove the terraces because they’re just concrete, and replace them with more soil and planting area
- Make the subdivisions of the garden less rectilinear so it feels a bit less brutal
- Lower some areas of the terraces a bit to get a bit more privacy (the garden is overlooked)
- Severely reduce the grass lawn area, because it requires frequent mowing and is not very ecologically diverse
- Rebuild the path to make it curvy and add some planting area in a sunny spot by it
- Keep the garden adaptable and don’t make anything too permanent (by cementing it in place) — I, or others, may want to rearrange things in future
Executing the plan
I started on this in 2019. Progress was slow at first, because a large part of the plan involved digging out the terraces, and there was some question about whether this would undermine the foundations of the house. That could cause the house to fall down. That would be bad.
I talked to a structural engineer, and he specified a retaining wall system I could install, which would retain the house wall and foundations, act as a raised bed, and is made out of wood so would have low embodied carbon compared to a (more standard) masonry wall (which is about 40kgCO2e/m2, see table 11 here). There was various other research and considerations about adjoining property, safety, drainage, appearance of the materials as they age, and suitability for DIY which fed into this decision. I can go into the details if anyone’s interested (get in touch if so).
What followed was about 10 months of intermittent work on it, removing the old terraces, digging a pond and sowing some wildflowers, installing the new retaining wall, fixing drainage through the clay, bringing in soil, laying a clover lawn, and rebuilding the path.
I’m pretty pleased with the result. There are a few decisions in particular which I’m quite pleased worked out, as they’re not a common approach in the UK and were a bit of a gamble:
- Clover patio. Rather than a paved patio area (as is common here), I planted clover seed on a thin bed of soil with a weed control membrane beneath. This has a significantly lower embodied carbon than paving (around 100-200kgCO2e/tonne less, if imported natural stone was used, which is the standard in the UK at the moment), and drains better, so it doesn’t contribute to flash flooding runoff. With rain becoming less frequent but more intense in the UK, runoff is going to become more of a problem. My full analysis of the options is here. I chose clover for the planting because it doesn’t require mowing, and should stay short enough to sit on. As per table 1 of this paper, I might adjust the planting in future to include other non-grass species.
- Wooden retaining wall. I used Woodblocx, and it worked out great. It didn’t require any cementatious materials (which have high embodied carbon), just a compacted type 2 sub-base and their wooden blocks. It’s repairable, and recyclable at end of life (in about 25 years).
- Wood chip path. This was easy to install (wood chips over a weed control membrane), doesn’t contribute to flash flooding runoff like paved paths do, and is a good environment for various insects which like damp and dark places. It will need topping up with more wood chips every few years, but no other maintenance. The path edging is made from some of the old decking planks from the original garden (the ones which weren’t rotten).
- Water butt stands. These are all made from bits of old decking or Woodblocx offcuts, and make the water butts easier to use by bringing the tap to a more reachable level. I also made a workbench out of old decking planks.
Subjectively, now the garden’s been basically finished for a year (I finished the final few bits of it the other day), I’ve seen more insects living in it, and birds feeding on them, than I did before. Yay!