Garden Q&A: Why are my rose leaves turning yellow and falling off?

Whether you're a gardening beginner or expert, Irish Examiner columnist Peter Dowdall has the answer to your questions

If your rose leaves are turning yellow and dropping off at this time of year, it’s most often due to black spot, a common fungal disease that thrives in warm, damp conditions, writes Peter Dowdall. File pictures

Question

Why are the leaves on my roses turning yellow and dropping off?

Answer

If your rose leaves are turning yellow and dropping off at this time of year, it’s most often due to black spot, a common fungal disease that thrives in warm, damp conditions. 

Look for dark blotches on the leaves, followed by yellowing infected foliage, and then leaves that drop prematurely.

As with most fungal problems, prevention is better than cure. To keep roses healthy, prune to allow good air circulation through the plant, removing crossing branches and any infected growth.

Water at the base of the plant, not the foliage or flowers, and clear away fallen, infected leaves to reduce spores. 

The healthier your rose is, the more resistant it will be to these problems.

Yellowing without black spots can be a sign of nutrient deficiency, especially if older leaves are affected first. 

A feed high in potassium and magnesium, which most rose feeds will contain, should help.

If it is a new plant, then drought or lack of watering may be the problem. This will stress roots, causing leaves to yellow. 

Roses like moist but well-drained soil; water deeply once or twice a week rather than little and often.

Finally, it’s perfectly normal for a few older leaves to yellow and drop during summer as the energy of the plant goes into new growth and flowers. If the rest of the plant looks healthy, it’s nothing to worry about.

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