Last year I experimented with a green mulch in the polytunnel. It didn’t really work out, far too much growth and lots of time spent keeping the mulch down. Which kind of defeats the point of a mulch!
This year, I’ve decided to stick with a grass/hay mulch, from the orchard area in the forest garden. I will cut down on the amount of grass but it is useful as a crop for mulching and as a habitat for wildlife (I think bumblebees nest in grass tussocks?), so I’ll keep an area of grass long-term.
There’s a series of soaker hoses under the surface, plastic funnels to water lower down, a layer of cow muck and then grass mulch on top to keep the moisture in. Tomatoes 🍅 to be planted out this afternoon!