We just bought a new home that has a trellis with climbing roses. What is the best fertilizer to use for these roses?
One based on sampling your soil and having it tested. If you buy a rose fertilizer and apply it for some years you may overdo the phosphorus in particular, if your soil does not happen to be deficient in this or another nutrient that a "food" style fertilizer product (rose "food", evergreen "food" etc.) supplies, based on the idea that you just have to match up the type of plant with the product rather than the soil with the product.
What Ron B entered is good. Unfortunately, roses are so forgiving that they almost singularly represent a classic ' leave 'em alone' plant. If you are a cemetary raider, you have taken rose cuttings from plants that have been ignored for (in some cases) generations! There is no question that CARED FOR roses not only thrive, but are capable of giving immense pleasure. Lucky for us, even the ignored roses will please.
If the rose is already established which sounds like it is in your case. A bag of combosted manure worked in lightly around will provide enough nutriments and soil amenments to keep the rose healthy. Roses do not like competion so its best to keep other plants away from the bottom of the rose.
Thank you for answering. I have just bought a home with a climbing rose/trellis and need much advise. :)