Gardeners can help roses bloom for longer and fight black spot by spraying them with diluted milk, a common household item. The treatment, shared on the Gardening Hints and Tips Facebook page, involves watering the base of the plant every two weeks.
How diluted milk controls black spot
Karen Powell posted a photo of her blooming pink rose on the Facebook page, 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.”
Cow’s milk contains natural proteins and enzymes with antifungal properties that can kill the spores. Milk works best when exposed to sunlight, as it creates an environment less hospitable to fungus and can also help form a thin coating that stops spores from sticking to the plant.
Other gardeners share their tips
Other gardeners also recommended the hack, while others suggested using baking soda. 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.”
Black spot is the most serious disease of roses, according to the Royal Horticultural Society (RHS). A badly affected rose can lose a large proportion of its leaves, reducing the plant's vigour.
Additional control methods and hygiene
The RHS also recommends using a non-chemical control, which can be started in the autumn by collecting 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.”
Keeping black spot at bay can also help roses stay healthier for longer, allowing them to maintain their foliage and continue flowering well into early autumn. It's important not to rely on homemade remedies; however, with good garden hygiene recommended as the first line of defence. Remove diseased material, clear up infected fallen leaves, and avoid creating conditions where foliage remains wet for long periods.
As September transitions into autumn, it's important to get the disease under control to help prevent black spot from returning next year.
