I know – yawn! Not pruning hydrangeas again! But pruning is one of those subjects – correction; the subject – that, to most gardeners is like its and it’s is to me – impossible to remember with confidence*.
Hydrangeas are much simpler. But can I just add the caveat that although I am going to talk as though there are only three species, there are dozens more, and modern breeding has made the situation more complex. But, basically…
Hydrangea paniculata kinds and H. arborescens cvs, that all flower at the end of the current year’s growth, are pruned now, cutting back the previous year’s growth quite hard. Remove the old flower head, if present and prune back to the bottom pair of buds if you want the strongest, longest growth and the biggest flower heads. Pruning is not absolutely necessary but if you do not prune then the plants get rather twiggy and the flower heads are much smaller.
Mophead hydrangeas (Hydrangea macrophylla or ‘bigleaf’ hydrangeas) are less hardy and they flower (usually) on sideshoots from the previous year’s growth. If they are pruned hard, like the above, they will make lots of growth but no flowers (except in maritime areas and with modern, everblooming types).
So pruning consists of lightly pruning off the old flower heads (which are often left all winter to protect the shoots below) back to the upper pair of healthy buds. My H. paniculata are planted outside but this mophead hydrangea is in the greenhouse, hence a little bit more advanced that it would otherwise be.
When plants get more than a few years old you can thin them out and remove a few of the oldest stems, at ground level. But do not chop back an old plant to near the base to keep it small – it will grow back to the same size very quickly and have no flowers.
*of course the apostrophe usually denotes possession or belonging to, and is NOT a plural – so avail of our two-for-one offer on banana’s should be avail of our two-for-one offer on bananas because other wise I am wondering about your banana’s what? These are commonly called ‘greengrocers’ apostrophes’ (or a greengrocer’s apostrophe’) because you so often see Sprout’s and apple’s for sale. I enjoyed the greengrocer’s bananas would be fine. And you don’t need an apostrophe for HGV’s, hgv’s and CD’s either. HGVs and CDs are fine – that is what the capitals are for, to avoid confusion and negate the need of other punctuation such as apostrophes.
But when it comes to its and it’s the rule changes – after all its can be ‘it is’ or ‘belonging to it’. So it’s means it is or it has (showing something is missing) and its is the possessive one, meaning belonging to –
it’s a shame the dog embarrassed me in front of my mother-in-law
the dog kept licking its bottom in front of my mother-in-law.