Gardeners are being urged to spray roses with diluted milk in September to treat black spot, the most serious fungal disease affecting the plants. The natural remedy, shared on the Gardening Hints and Tips Facebook page, has been endorsed by fellow gardeners as an effective way to control the disease.
Natural remedy for black spot
According to the Royal Horticultural Society (RHS), black spot is the most serious ailment affecting roses. A severely infected rose can shed a substantial portion of its leaves, weakening the plant's overall vitality. The disease leaves plants covered in dark marks, yellowing foliage, and early leaf fall.
On the Gardening Hints and Tips Facebook page, Karen Powell shared a photograph of her flourishing pink rose, with the caption: "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."
How milk works
Cow's milk contains natural proteins and enzymes with antifungal qualities that can eliminate the spores. Milk proves most effective when exposed to sunlight, as it creates conditions less favourable to fungus and can also help form a fine coating that prevents spores from adhering to the plant.
Fellow gardeners also endorsed the technique, while others suggested baking soda as an alternative. Lou Deane wrote: "I use my nearly empty milk cartons. Fill them up with water and empty onto the roses at least once a week."
RHS advice and prevention
The RHS recommends a non-chemical approach that can begin in autumn with the gathering of fallen leaves. They said: "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 will help delay the onset of the disease, but are of limited value because spores are bound to blow in on wind-blown rain from elsewhere."
Managing black spot effectively can also help roses remain healthier for longer, enabling them to retain their leaves and continue flowering well into early autumn. It is crucial not to rely solely on homemade solutions; instead, maintaining good garden hygiene is the primary defence. Clear away diseased material, remove infected fallen leaves, and avoid creating conditions in which foliage remains damp for extended periods. As September gives way to autumn, it becomes vital to bring the disease under control to help stop black spot from reappearing next year.
