As a summer marked by record-breaking heat and prolonged drought comes to a close, Monty Don reflects on how it has tested gardeners across the country. From parched borders to sun-scorched lawns, he looks at the impact of low or no rainfall and offers some solutions for the plants worst hit. Yet amid the challenges, there is reason for optimism. As the gardening year turns towards autumn, he gathers seed, takes cuttings and prepares the ground for seasons to come, proving that gardening is always an act of hope. Joe Swift visits a family-run nursery in Dorset and Rekha Mistry shares the results of her container challenge. In Essex, a grower showcases his agaves and in Cumbria a young couple share tips for a colourful garden