So, the works have begun. The scorched scrubland that was the garden is now a large pile of earth and – excitingly – a big old hole for the rainwater harvesting tank that I hope is going to help us navigate these increasingly dry summers and wet winters.More on that once it’s in. For now, though, the matter of soil. So much of it! Soil everywhere! I am determined to send as little of it off in a skip as possible. And what do you do with mounds of earth? You make mounds.Among the notable mounds I have admired (and there have been many) are those made of crushed substrate in the walled garden at Knepp in West Sussex. When the rewilding estate’s custodian was showing me around, she said head gardener Charlie Harpur and his team demolished an outbuilding and had it deposited in its entirety on the croquet lawn.What could have been carted off in a skip became a mesmerising dry garden planting base. We visited on the hottest day last summer and it was a golden, shimmering mass of swaying colour and umbellifers, its undulating landscape providing habitats for all sorts of insect life.I have neither an outbuilding to demolish nor a croquet lawn to deposit it on, but I will be making mounds in our (far more modest) garden. It is a classic long and skinny urban plot, and I’m depriving my children of the biggest lawn possible because we live near a park and, well, the garden isn’t just for them. Instead, I want to create the kind of surprise and intrigue that makes the best gardens, and that requires a level of partition.skip past newsletter promotionafter newsletter promotionI’m thinking of some mounds at the far end of the plot: a couple around where the compost pile will be, and then another one or two towards the end, where I’m planning wilder, looser planting where the kids can run amok (I’m not a total monster).If you’re not unearthing a load of soil, hugelkultur is the ancient practice of building mounds from decaying wood, mulch, rotting branches and twigs, followed by topsoil and plants. Start by removing any turf, which you can then layer upside down on top of the wooden base before mulching – it compacts the materials and speeds up the decay necessary to boost soil nutrition.Once you’ve got your mound in place, plant it as you would a flowerbed, thinking about repetition, structure and a variety of heights, colours and textures.Mounds can be good for creating privacy without the infrastructure of a more formal boundary: trees and shrubs can be planted alongside smaller perennials and ground cover, extending your planting space up as well as out.