Q Why did white flowers turn pink on my 18-year-old mophead this year? G F MOBSBY, BY EMAIL A White hydrangeas have a tendency to develop a pink tinge as the flowers age or when exposed to strong sunlight and intense heat. So, your plant behaved much as expected in the hot summer. Depending on the weather next summer your plant will probably flower as normal, with pristine white blooms. Q Am I too late to plant out a potted hydrangea? K MORGAN, BY EMAIL A Potted hydrangeas can be planted out at any time, provided the soil isn’t frozen or waterlogged. The best time to do it is in autumn because it’s easier to keep them moist while they establish, unlike when planting out in summer. You can add some slow-acting fertiliser to the planting hole now or use a general plant food in spring or summer. Q How should I treat fluffy white bugs on stems and leaves? AUDREY JAMIESON, BY EMAIL, AND VERONICA MOORE, NORFOLK A Hydrangea scale insects will suck sap and weaken the plant, depositing a sticky substance called honeydew that falls onto lower leaves and is colonised by black, sooty mould. The adults look like tiny brown limpets on stems and leaf undersides but when they release their eggs they leave a white, waxy cottony material in which the eggs and larvae hide. Spray the plant with Resolva Bug Killer (£4.50 for 1L spray) several times to control them. Q Why hasn’t my hydrangea ‘Runaway Bride’ flowered? PATRICIA JONES, BY EMAIL A Hydrangea ‘Runaway Bride’, Chelsea Plant of the Year 2018, is renowned for its freeflowering habit with white blooms produced on arching shoots, so I expect your plant didn’t flower this summer because it was too young. The yellowing leaves may be the result of simple autumn colouration but it could also be that it needed more feeding during growth. It’s best not to prune it at all this first season, but repot it in spring and feed it more often. Q When’s the best time to move a rooted cutting I planted this year? P DELLEA, LONDON A As with all hardy shrubs, it’s best to move your hydrangea cutting while it’s dormant, between October and March.