Summer's end comes every year with inevitable regularity, a part of the world's natural rhythm, and full as always in equal measure with sadness and exquisite beauty. In the garden the lowering light softly illuminates those gentle colours which the intense midsummer sun bleached out. Powder blue asters contrast with the first of the soft buttery golds and russets of the turning leaves and seed heads are forming at the tips of the swaying stems of ornamental grasses preparing to feed the winter's migrant birds. In the fruit garden – or in my case, in the hedge along the drive – the plums are turning a luscious smoky purple and the apples are reddening up to ripeness. This is the time when summer's shades of green slowly start to turn, one leaf at a time, a hint of yellow here and a flush of orange there until there's no avoiding it, summer is on its way out. We aren't the only ones to notice, swallows and house martins are lining up along the phone wires making ready to leave as the quantity of insect food declines and in the cooler mornings orb web spiders are suddenly noticeable on garden shrubs and hedgerows sitting patiently in the centre of their intricately woven traps. September is a time of change in the garden just as it is in the fields and woods around. Not yet quite autumn but no longer really summer, it's a time when pickings of fruit and vegetables are reaching their peak and it's time too for us to appreciate the garden for what it is, our own part of the glorious natural world, not really under our control at all but subject to the turning earth, changing levels of daylight and falling temperatures. Besides the asters, the other typical flowers of the season sedums are coming into flower too, our native stonecrop is one with yellow flowers but cultivated forms include some with deep purple leaves like Sedum 'Purple Emperor', most are pinkish or white and there are some varieties with names that make me smile like 'Stewed Rhubarb Mountain' and 'Red Cauli'. One of my favourites flowering now is Caryopteris, a scrubby little shrub we forget about until this time of year when it becomes worthy of a place in any sunny garden, it's vivid flowers a perfect reflection of a cloudless blue September sky.