Roses are popular in summer gardens due to their magnificent blooms – but this pretty plant may not flower again if gardeners are not on the lookout for black spot disease.
Black spot disease is a serious fungal infection that is common in summer as it spreads in warm rainy weather, and can first be noticed if a rose plant has yellowing leaves with big black spots on them.
While black spot disease will not outright kill roses it will sap the energy of the plant which will result in fewer and lacklustre blooms or even no flowers at all.
Over time the rose’s weakened state will also make it susceptible to other diseases as well as attract many pests which will eventually cause the flower to die.
This disease is challenging to get rid of once it makes its way into garden soil but Alan Titchmarsh has shared it is very easy to prevent black spot disease from hurting your roses.
In a 2011 episode of Love Your Garden, Alan shared that making sure to water roses properly in the summer is the key to preventing not just black spot disease but mildew and mould.
Alan said: “They [roses] love moisture and that will help to stop them from showing signs of mildew – that white powdery stuff – and black spots.”
“It’s when they are short on moisture they tend to get these diseases but they do need food.”
Always water roses deeply at the soil level rather than letting the water drip down the foliage as the disease carries through moisture, so the longer the rose leaves are wet the more susceptible it is to disease.
It is also best to water roses in the morning in summer as it will allow the leaves to dry out quickly and the cooler temperature means more water reaches the roots rather than evaporating into the air.
Alan also shared that providing roses with the proper nutrients will also keep them healthy which will also make them more resistant to disease.
He said: “Sprinkle some rose fertiliser around the soil above the roots in March and again in June.”
Fertilising roses too late in summer may not give the plant enough time to utilise the nutrients it needs which can lead to reduced flowering, poor growth and the plant being vulnerable to disease.
June is typically when roses begin producing new flowers so fertilising now will also prepare them for a strong summer cycle, leading to bigger and more abundant flowers.
Many gardeners boost their roses with homemade feed of banana peels, crushed egg shells, coffee grounds and Epsom salt but you can also buy a balanced fertiliser with equal parts nitrogen, phosphorus and potassium to feed roses.
Make sure it is a slow-release fertiliser to provide roses nutrients over a long time and also check the fertiliser contains micronutrients such as magnesium, iron, manganese, or zinc which will not only prevent rose diseases but help the flower bloom this summer.
