After trying different methods of mulching the soil on empty beds over winter, I find a good layer of manure or compost topped with lashings of newspaper works well. The paper hardens wonderfully, (the two freebies, Evening Standard and morning Metro are perfect, just open in the middle, or for extra thickness lay down in closed format). During the first year of working my plot, I covered sections with donated silage sheets to block the weed growth, but oh boy slugs love the stuff, and it’s not biodegradable. Worms love paper and I find fewer slugs hiding underneath. I usually cover with a fine layer of soil or grass clippings, but last week I used planks of wood and a few bricks to keep in place. So a couple of beds mulched and ready for hibernation, or a reading bonanza for anyone passing.
For beds with growing veg, I like to use a green manure, Phacelia tanacetifolia, sowing in August/September for overwintering. This is such a beautiful delicate flower with lovely fern like foliage, self-seeds, and attracts masses of hoverflies in the summer hungry for aphids!