Watch out for…
■ Black blotch Black marks anywhere on the plant. Worst in wet summers. No cure; destroy plants.
■ Caterpillars Will eat buds and leaves – remove them.
■ Powdery mildew Dusty white leaf infection encouraged by dry summers and drought at the roots. Water well – or spray.
■ Slugs and snails Use organic pellets from early spring. Overwintering crowns and new shoots are especially vulnerable to being eaten.
Leaves affected by back blotch