Powdery mildew, a white fungal growth that typically develops on the leaf surface of plants and is caused by dry soil and moist/humid atmospheric conditions, can be a problem at this time of the year, disfiguring the appearance of foliage and affecting growth. Various fungi are the cause of this condition, with some plants – peas, phlox, rhododendron, roses, hydrangeas, lilac, container-grown plants – particularly affected. While affected plants can be sprayed with a systemic fungicide, I prefer to avoid this. Instead, try to reduce the risk of the disease spreading by nipping out affected leaves at the first sign of infection. Collecting and burning any fallen leaves will also stop the fungus from over-wintering, while mulching/ regular watering will help prevent it from getting established.
Once their stems start to yellow, start harvesting onions, shallots and garlic (below left). Try to choose a sunny day, when you can leave the plump bulbs on a table outside to dry, a process that will considerably extend their storing capabilities
I – or should I say "we" – have almost finished eating the last of the delicious early potatoes, while the later maincrop has still to come. But it's important to remember that underground slug damage to tubers can increasingly be a problem at this time of year, so take appropriate precautions. Otherwise you run the risk that those tasty spuds (below right) will be bored through with fat slug-sized holes.
Once the scented, purple flower spikes of lavender (Lavandula, above) have faded, cut away the flower heads along with roughly an inch of this year's growth (making sure that some young, green growth remains, as the plant doesn't regrow easily from old wood) to encourage a bushy vigorous plant that will flower well again next year. Badly neglected specimens are best replaced with new plants.
