Mutant hydrangea?

[tigerlelly]

I just went to admire my extremely blue and beautiful hydrangea after answering the previous post and I noticed something really odd about it. One of the blooms, only one, has flowered as a lace cap and all the other blooms are bog-standard. What could have caused this to happen?

[rowanwitch]

it has prduced shoots either below a graft or it is reversion... at the end of the season cut out all the bog standard growth and if it is graft make sure you remove new growth from below..if it is just reversion to be honest you might as well give in as it will keep doing it