We have a camellia ( 5ft ?) in a large pot, that is otherwise healthy and has given gorgeous flowers for years. Last year it produced buds that didn't open, but just shrivelled in early summer and fell. . I read up and the only thing I could find was making sure it was well watered in the previous autumn.
Is in a sheltered, south facing garden in London and other camellias along the street ( front gardens so north facing - two in pots and 1 in the ground )have either flowered and gone or are mostly out. Ours has got to the same stage as last year - in ' just about to bloom ' bud, - but going no further . In years previous to the last, it would have bloomed and gone by now.
My thought is that it could be pot bound ( huge pot, btw - no fan but my husband's idea at the time) it is diligently fed and watered and in the right soil etc. Any ideas ?