Diluted milk can help control black spot on roses, leaving them with glossy green leaves and helping them bloom longer into early autumn, according to a tip shared by gardeners.
Black spot is a common fungal disease that leaves roses with dark patches, yellowing foliage and premature leaf drop. The Royal Horticultural Society (RHS) describes it as the most serious disease affecting roses, noting that a severely infected plant can shed a substantial proportion of its leaves and lose vitality.
How diluted milk works against black spot
On the Gardening Hints and Tips Facebook page, Karen Powell shared a photograph of her flourishing pink rose. Her caption read: "Here's how your rose will look when you control black spot with diluted milk. Water it at the base every two weeks. It gives nice green glossy leaves. It also helps feed them."
While the method may sound unusual, cow's milk contains natural proteins and enzymes with antifungal properties that can eliminate the spores. Milk performs best when exposed to sunlight, as it creates an environment less favourable to fungus and can help establish a thin coating that prevents spores from adhering to the plant.
Other gardeners' tips and RHS advice
Other gardeners endorsed the tip, while some proposed using baking soda. Lou Deane commented: "I use my nearly empty milk cartons. Fill them up with water and empty onto the roses at least once a week."
The RHS also advises a non-chemical approach that can begin in autumn with the gathering of fallen leaves. The society stated: "If practical, pick off and dispose of any leaves that remain on the plant over the winter months. Prune out all stem lesions in spring before leaves appear."
These actions help delay the onset of the disease, but the RHS noted they are of limited value because spores are bound to blow in on wind-blown rain from elsewhere.
Keeping roses healthy into autumn
Keeping black spot under control can help roses remain healthier for longer, enabling them to retain foliage and carry on flowering well into early autumn. Gardeners are advised not to rely solely on homemade solutions; good garden hygiene is the primary line of defence. Remove affected material, clear away infected fallen leaves, and avoid conditions where foliage stays wet for extended periods.
As September gives way to autumn, bringing the disease under control is vital to help stop black spot from reappearing next year.
