Alan Titchmarsh has shared a simple, one-ingredient trick for hydrangeas that helps them thrive in hot weather. The gardening expert, speaking on ITV's Love Your Weekend, recalled a technique from his early career at Ilkley Council's Parks Department in the 1960s.
The Hydra Clue
Titchmarsh explained that the key lies in the plant's name: 'hydra' is derived from the Greek for 'water'. In BBC Gardeners' World Magazine, he wrote: "A friend bemoaned recently that she had no success with hydrangeas on her free-draining, sandy soil. I pointed out (politely, of course) that the clue to their cultivation lies in their name." He added that hydrangeas are "thirsty plants and will not thrive where moisture is in short supply."
Aluminium Sulphate Treatment
The trick involves using Hydrangea Colourant, based on aluminium sulphate. Titchmarsh said: "When we grew them in pots back in my parks department days, we watered them with Hydrangea Colourant." The same product, now described as aluminium and iron salts, is still sold today by Westland Horticulture. It works by acidifying the soil, turning pink hydrangeas blue or mauve, and blue blooms to a "summer sky" shade.
Impact on Bloom Colour
The results can be dramatic. Titchmarsh noted that pink hydrangeas can shift towards mauve, while blue blooms take on a lighter tone. Westland Horticulture confirms the product can turn pink hydrangeas blue and nudge darker pink flowers into mauve.
Annuals for Instant Impact
In related advice on his YouTube channel, Titchmarsh recommended using annuals to fill gaps in borders. He recalled buying marigold seeds when he was short on money, saying they "cost me next to nothing." He advised: "If you suddenly find yourself in June or July with a hole in a bed or border, go to annuals because they'll give you that instant hit."
