We have an almost 20 year old climbing rose (John Cabot) that we love lots. It is part of a largish garden, surrounded all around by many perennials. It has been trained to climb up a trellised brick wall and has attained a height of 12 feet and width of maybe 7 feet.
It blooms beautifully each June but by August and beyond it looks more than worse for wear with leaves falling off to the extent that some of the higher climbing canes have died :(.
I wanting to see if I can keep this JC more heathy as the summer progresses and I am wondering if paying more attention to its nutrition through the whole season might be helpful?
The only feeding it has gets from me is via compost laid down a couple of times each season.
Am I correct in thinking that roses are "heavy feeders"? Would/should compost alone be enough for such a large rose bush? *If* supplemental fertilization would help, what are the "nuts and bolts" of applying it? Does one simply use a watering can with mixed in fertilizer, applied to the base of the rose or does one need to also apply it further away from the base given its large size?