I have a Chinatown rose, which I planted in a pot last year. It lost most of its leaves over the winter. The stems are very spindly, but they are nice and green. The worrying thing that I discovered yesterday was that it now has little black spots on these main stems, and I am wondering if it is because it has been growing in one of these plant pots that have raised drainage holes, which means that water can collect at the bottom. I don't know why they sell plant pots like that in reputable garden centres. It has been a very wet winter where I live. Many thanks.
Hi Beverly and thanks for the question. It could be a problem of water retention indeed and could be some black spot fungus or mold getting started. I would suggest transplanting the rosebush to a new and larger pot with drainage holes in the bottom. I like to add some pea gravel or 3/4" gravel in the very bottom of the pots, then put a cut out piece of landscape fabric over the gravel layer and use a good potting soil for the fill. This helps assure good drainage that also allows the right moisture for the root zone yet not too much to help get molds and funguses going. When I water my pots I never let them sit in water in the drainage pans longer than an hour and try to keep it at no more than 30 minutes. When transplanting the rosebushes, I water them in with some water that has both a good root stimulator and a product called Super Thrive mixed into the water. This goes a long way to holding down the transplanting stress and getting the roots going. I happy root zone makes for an awesome delight above! Spraying the rosebush with a product called GreenCure, applied at the cure rate would be good too. Link: >> http://greencure.net/