what causes black edges on rose petal
Alice Aks - CA, Zone 9. After reading all of the above, I was going to mention temperature changes. Here in my colder climate, I get some red rose petals that have that black edge on them. Most of the time it is due to a light frost that gets on the roses on some cold evenings. The edges of the petals get frost bitten and look black and disfigured a bit. How heavy a frost and the timing can cause more of the black edges too. Stan the Roseman Bearrose1954 - Colorado, Zone 5.