From the start we’ve been interested in how we improve the biodiversity values of urban planting. Nectar loving insects obviously love flowers, & PlantLocks can be a way of introducing food plants for insects. Dusty of Living Roofs suggested a cornfield wildflower mixture on a very poor soil. Below is this over 2 consecutive summers, left to its own devices (rainfall only). Hoverflies & bees seemed to be frequent visitors.