Anne, from your photo, I'm not positive which kind of camellia do you have, sasquana or japonica? It looks like japonica. That's the one commonly found in old southern gardens. Either way this is what I found on the web as far as feeding:
Fertilizing. Feed with an acid-forming azalea or camellia fertilizer in spring, after the flowers have dropped; fertilize again in the midsummer if growth seems sluggish or foliage looks sparse and begins to lose its deep green color. Apply at the rate recommended on the label. Don’t overdo it, as plants grown in fertile soil need little fertilizer―and never feed plants that are sick or distressed.
Chlorosis (yellow leaves with green veins) results from planting in neutral or alkaline soil; to correct, feed plant with chelated iron and amend soil with sphagnum peat moss and/or garden sulfur to adjust the pH.
Tea scale is a common pest. These pests look like tiny brown or white specks on leaf undersides; sooty mold grows on the honeydew they secrete. Infested leaves turn yellow and drop. To treat tea scale, apply horticultural oil or a systemic insecticide such as acephate (Orthene) or dimethoate (Cygon), following label instructions.
I have 2 japonicas that I need to move, as they are in full sun and in serious need of pruning and thinning out. I don't know much about that, but I'll have to learn something soon myself. I love the flowers on these plants. I always use miracid on mine when they start turning yellow. They just bloom themselves out. But often than not, late frosts gets quite a bit of my blooms. Enjoy your plants. I found a pot of sasquana on clearance a few months ago and it has 3 plants in it. It is seriously in need of being separated , repotted or planted in the ground. There's so much to do and it's soooooo hot here already.
O wow, look what I just found: https://www.americancamellias....
Enjoy your new home and gardens!