From the Royal Horticultural Society
August is usually one of the hottest months of the year, making watering essential. Try to use grey water wherever possible, especially as water butts may be running low if it has been a dry summer. August is traditionally holiday time, so you might need to enlist the help of friends and family to look after the garden while you are away. When you are at home, take the time to prune wisteria and summer-flowering shrubs such as lavender once they’ve finished flowering.
List of RHS August suggestions…