Acanthus mollis and A. spinosa – in some conditions get very unsightly with mildew at this time of the year. Leave the flowering spikes intact but remove any other affected foliage down to the ground. Young fresh green leaves should soon appear.
Decrease watering and let Hippeastrums go into dormancy.
Thalictrum delavayi ‘Hewitt’s Double’ is a very stately addition in July-August and when established can reach 6ft. plus. It can be used not only in the herbaceous border but planted between evergreen azaleas to give added summer colour.
Astilbes are at their best now and prefer a moist, slightly damp position but they can be grown anywhere (except deep shade) as long as they are kept well watered.
Dahlias e.g. ‘Bishop of Llandaff’ needs to be kept well staked and regularly fed and watered. Continuous cutting or deadheading will promote flowering.