I have a few Hydrangeas that have not been doing their best. I think I have the exposure down, and their colors. I need advice on what fertilizer is best for them and when, how much and how often to apply it. I try to stay as organic as possible.
According to Hydrangeas: A Gardeners’ Guide by Toni Lawson-Hall and Brian Rothera (Timber Press, 1995), hydrangeas do not generally require special feeding. If you wish, you can apply a general fertilizer twice a year. “As important as feeding, and in fact another method of supplying nutrients, is mulching.” The authors suggest using mature compost or leaf-mould. Mulching in the spring to a depth of about 3 inches will help protect the roots of your hydrangeas from drying out (but never put mulch directly up against the base of your shrubs). Mulching also suppresses weeds. Since you garden organically, mulch may be your best bet for supplying a slow and gentle dose of nutrients. If the plants continue to fare poorly, you may want to do a soil test to see if there is some kind of nutrient imbalance that needs correcting.