There is a particular satisfaction in a rose that is performing well in midsummer. Deep colour, healthy foliage, no black spots, no yellowing leaves, just the plant doing exactly what it is supposed to do. For a lot of gardeners, though, that picture does not quite materialise. The roses bloom, but there is an undercurrent of trouble: leaves going yellow and dropping, dark spots appearing from mid-June onwards, flowers that look good for a week and then trail off. These are not inevitable. They are, almost always, a result of two things: the wrong feed, or no disease prevention. Luckily for you, we have a straightforward fix!

Why Roses Are Different from Everything Else in Your Garden

Roses are not a plant you can feed with a general-purpose product and forget about. They are, as any serious rose grower will tell you, hungry feeders with a very specific set of nutritional requirements. They want high potash to fuel flower production. They want trace elements, particularly iron and magnesium, that are absent from most off-the-shelf fertilisers. They need the soil to be at a slightly acidic pH, typically between 6.0 and 6.5, to make those nutrients available to the roots. Get the feeding wrong and the rose will still grow, but it will not perform as it could, you will see yellowing leaves, poor flower colour, and weakened growth that becomes a gateway for disease. Yes, these babies are the divas of the flowering world!

The other thing that makes roses different is their susceptibility to fungal disease. Black spot (Diplocarpon rosae) and powdery mildew are the two main problems, and in the UK’s warm, wet summer conditions they’re not occasional visitors, they’re a constant background threat. Once established, black spot spreads quickly: yellow-ringed black spots appear on the leaves, the foliage yellows and drops, and by August an affected plant can look completely stripped. The disease overwinters in fallen leaves and re-emerges the following spring so it’s a continual problem!

Why Black Spot Was Not Always Such a Problem

There is an interesting piece of horticultural history behind the rise of black spot in the UK. Before the Clean Air Act of 1968, sulphur dioxide in the atmosphere from coal fires and industrial pollution acted as a natural fungicide, suppressing the fungal spores that cause black spot, meaning rose growers of earlier generations simply did not face the same level of disease pressure. Once the air cleaned up (which was, obviously a wonderful thing!) black spot became the persistent challenge it is today.

The solution that rose growers arrived at was a straightforward one: replace the protective effect of atmospheric sulphur with a topical sulphur application. Sulphur is the natural enemy of black spot and powdery mildew, and it works by creating a surface coating on stems, leaves and surrounding soil through which fungal spores cannot germinate.

What Professional Rose Growers Actually Use

Sulphur Rose from Greenacres Direct is a wettable sulphur formulation used by professional rose growers and rose nurseries across the UK. It is not a chemical fungicide, it is sulphur in a soluble, sprayable form. You dissolve it in water and apply it to the stems, foliage and surrounding soil. It is safe for bees, pets and wildlife, and it can be applied throughout the year.

The key to Sulphur Rose is regularity. It works best as a preventative rather than a cure. Start applications early in the season and continue monthly through the growing period, reapplying after heavy rain. The fungal spores cannot establish in a sulphur film, so you are keeping the disease from getting a foothold rather than trying to fight it once it has taken hold.

Feeding Roses Correctly: What to Look For in a Rose Fertiliser

NutraRose Micro is a specialist rose fertiliser developed with professional growers in mind. The formulation contains a high potash content for flower production, a full micronutrient package including the trace elements roses specifically need, and a pH-balancing effect that keeps the soil in the slightly acidic range roses prefer, particularly important if you garden on alkaline or chalky soil or in an area with hard water.

The timing through the season matters: apply in spring as growth begins, again in early June before the main flowering period, and once more in mid-July to support the second flush. Avoid feeding after the end of August, as late season feeding can promote soft new growth that is vulnerable to frost damage.

The Rose Bundle: Everything a Rose Needs, Together

Greenacres Direct have put Sulphur Rose and NutraRose Micro together in a Rose Bundle priced at £44. The bundle covers up to 20 rose plants for the complete growing season – disease protection and specialist feeding in one purchase, from the same source that professional growers use. It is the most practical way to make sure both the essentials are covered.

Practical Summer Rose Care: A Month-by-Month Summary

June

• First application of Sulphur Rose if not already done in spring
• Feed with NutraRose Micro as the main flowering period begins
• Deadhead spent blooms regularly to encourage continuity of flowering
• Check for early signs of black spot and act immediately if found

July

• Reapply Sulphur Rose monthly (or after heavy rain)
• Second application of NutraRose Micro to support the second flush
• Continue deadheading – remove spent blooms back to the first five-leaflet leaf
• Water thoroughly at the base of the plant in dry spells; avoid wetting the foliage

August

• Continue Sulphur Rose applications
• Deadheading continues to encourage late season blooms
• Do not feed after the end of August
• Begin collecting fallen leaves and disposing of them (not composting) to reduce black spot spores overwintering

A Note on Hard Water

If you live in a hard water area, you may notice yellowing on your roses even when you are feeding them. This is often caused by the high lime content of the water raising the soil pH and locking out iron and magnesium. Sulphur Rose helps here too: as well as its fungicidal properties, it helps neutralise the alkalising effect of lime in the water and soil, making nutrients more available to the roots.

When to Call in Something Stronger

Sulphur is effective for prevention and for early-stage disease, but if black spot has taken a severe hold — particularly if it has spread to multiple plants and caused significant defoliation — you may need to combine sulphur applications with a thorough clear-up of all fallen material, and in extreme cases a proprietary fungicide. The key lesson is that getting the sulphur applications in place early makes it very unlikely you will ever reach that point.

For more on rose care through the year, take a look at our guide to pruning roses. And for the full rose care range, visit greenacresdirect.co.uk/rose-care.