The wall is the vineyard

When we bought the land in 2007 it was a sheep paddock with a collapsed wall along the top of it. Everyone who walked the site with us said the same thing: lovely aspect, shame about the wall, get a contractor to clear it and put a post-and-wire fence in.

I had spent eleven years as a hydrologist before this, and I looked at the wall and saw a drain. So we did not clear it. We rebuilt it, all 640 metres, by hand, over two winters, and we planted the first vines in the spring of 2009 below a wall that finally worked again.

What a drystone wall does to a slope

A mortared wall stops water. A drystone wall slows it down. Rain that hits the ridge above Wallgrow runs down the slope, meets the wall, and seeps through the gaps between the stones instead of sheeting over the surface and taking the topsoil with it. On a slope with thirty centimetres of soil to lose, that is the difference between a vineyard and a scree.

It also holds heat. Slate warms up slowly and gives it back slowly, and on a clear autumn night the rows nearest the wall run about a degree and a half warmer than the rows twenty metres below. In a marginal year a degree and a half is a week of ripening.

The plant in the cracks

Sedum acre — biting stonecrop, wall-pepper, a dozen other names — colonised the wall within three years of the rebuild. It grows in cracks with no soil at all, survives droughts that kill the grass, and flowers bright yellow for about three weeks in June. We named the estate after it because it seemed like a fair description of what we were asking the vines to do.

What it costs

We lose about four metres of wall a year to frost heave and sheep from next door. Tomás rebuilds it every December before pruning starts, one section at a time, with the same stones that fell out. It takes about nine days. Nobody has ever suggested we stop.