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Notebook · Guide 8 October 2026 · seasonal

Black spot on roses: what actually works

You won't banish black spot in a wet British summer, but you can keep it in check: clear fallen leaves, mulch in winter, water at the base, and choose less susceptible roses.

seasonalsave your money

If your roses are covered in black blotches and dropping yellow leaves by July, you're in good company. The RHS calls black spot the most serious disease of roses, and says most UK summers are wet enough for it to build up. The honest answer is that you can't get rid of it for good. Spores blow in on wind-driven rain from other gardens. What you can do is cut down how much survives on your own plants, slow the spread, and choose roses that cope with it better.

01At a glance

  • The cause: a fungus, Diplocarpon rosae, spread by splashing water and wind-driven rain.
  • Where it hides over winter: on fallen leaves, and in infections on young stems and buds.
  • What helps most: clearing fallen leaves, a thick winter mulch, cutting out stem lesions in spring, and watering at the base.
  • Sprays: the RHS recommends against fungicides, organic ones included, and doesn't recommend homemade remedies.
  • The long-term fix: less susceptible roses, with the caveat that resistance doesn't always last.

02How to recognise it

  • Purple or black patches on the upper side of the leaf, growing quickly, often with faint feathery edges where the fungus spreads out.
  • Yellowing around the spots, then the leaf drops. Some leaves fall without yellowing; some keep small spots and stay on.
  • It usually starts on the lower leaves and works upwards.
  • Small, black, scabby marks on young stems. These carry the disease through winter.
  • Badly affected plants lose most of their leaves and lose a lot of vigour.

You'll see markings from spring onwards, and they stay for as long as the leaves stay on the plant, so don't wait for them to clear.

03A year of keeping it in check

None of these steps works on its own. Together, they keep the problem down.

  1. Late autumn to late winter: clear up and mulch. Rake up fallen leaves and bin them rather than composting them. Where practical, pick off any infected leaves still hanging on the plant. Then mulch the soil with a layer of well-rotted compost or manure at least 5cm thick to bury anything you missed.
  2. Spring, before the leaves open: prune out stem lesions. Cut out any stems with black, scabby marks while you do the main prune. Work in dry weather.
  3. Spring and summer: water the soil, not the leaves. The spores need water to spread. A watering can or a soaker hose at the base keeps the leaves dry. Avoid sprinklers.
  4. All season: keep it airy. Space shrubs well, prune for an open centre, and grow roses in full sun so the leaves dry quickly after rain. On a climbing rose, good air movement along the wall or fence helps too.
  5. Through summer: pick up fallen leaves as they drop. Every spotted leaf on the ground is next year's infection.

04The honest bit about sprays

The RHS recommends against using fungicides, including organic ones, because of their wider effects on garden wildlife and soil. It also advises against homemade sprays, which are unregulated and usually untested. If you do choose a fungicide, the RHS keeps a list of those legally available to UK home gardeners. Even then, sprays work only alongside the hygiene steps above, not instead of them.

05Choosing roses that cope

If one rose drops all its leaves every year despite everything, the best fix is to replace it. Breeders do select newer varieties for resistance, and they're worth choosing. But be realistic. The RHS warns that resistance in newer cultivars often lasts only a few years, because new strains of the fungus appear. Hybrid teas, floribundas, climbers and patio roses are often susceptible. Older species roses are little affected.

06Mistakes that make it worse

  • Composting infected leaves. Bin them.
  • Watering over the top with a sprinkler or hose.
  • Crowding roses into a tight bed with no air moving through.
  • Leaving last year's leaves under the bush through winter.
  • Expecting a "resistant" label to mean immune.
Save your money
Don't buy a cupboard full of sprays. Hygiene and mulch do more, and the RHS doesn't recommend fungicides.
Use your own compost or leaf mould as the winter mulch. It buries spores and feeds the soil.
Replace a chronic sufferer rather than treating it every summer. A bare-root rose bought in winter is the cheapest way to do it.
Skip homemade sprays. They're untested, and they won't stop spores blowing in from next door.

How we checked this

Every care and safety claim on this page is verified against horticultural and veterinary sources.

Sources: RHS — Rose black spot · University of Wisconsin–Madison Extension — Black spot

Checked 8 October 2026. If our advice ever conflicts with the RHS, believe them and tell us.