Q. I discovered a "white fluffy" substance on the new growth stems of my hydrangea.
Thanks so much for any suggestions you may have.
Dear Gardener: From your description, the problem sounds more like a little bug problem of some sort. Mites are quite tiny and are very hard to see. In anycase, spray the fluff liberally with Ultra fine oil. It is available in most garden centers. Be sure it is the ultrafine oil, not dormant oil as it is too heavy for this time of year. Ultrafine oil is safe and non-toxic to you. I would be careful not to spray in the hot sun.