biannual flowering hydrangeas

welcome to GoY monster.
are you sure they are Hydrangea. I have never heard of any other than the shrub forms. someone will probably be able to help.

If you're sure they're hydrangea, when do you prune them? Do you cut them back after they flower, and not when they don't?

No, I only prune in the spring to take off dead heads after frost is over.

Hydrangeas are not biennial, they usually flower every year, and I wondered whether you were pruning them at the wrong time, but you're not. It may be that this year, because of the heatwave, they suffered a bit from drought and have decided conditions are not right to flower, but I don't know how long you've had the plants and how many years they've either flowered or not flowered?

I had one first planted about 5 years ago which didn't flower the next year but did the following one. It was at this stage that I realised that I shouldn't cut off the dead heads till after frosts were over so assumed that this was the problem. When it failed to flower the next year I planted another beside it to give flowers alternate years. That was last year and this year neither is flowering and no sign of any buds so not just late. The first has not flowered for two years now and the second has missed just this year. I have never heard of biannual hydrangeas either so I am begining to take it personally!

Weird - there's something going on, but I'm not sure what. I'd try feeding them regularly next year with something like Miracle Gro general purpose to see if that works. As you haven't mentioned any other problems, I assume the plants are otherwise healthy. You could also topdress the base of the plants with sulphate of potash around April time - this encourages flowering.

Thanks, I'll try that. The flower bed is under a forsythia hedge so it may just be rather sucked dry of nutrients.

And water, presumably - when it's not raining all the *!!* time

Hmmm. Perhaps I'll just learn to love bindweed. It doesn't seem to mind what you do to it!

Given their postion, I think they might not be getting enough moisture to initiate the forming of flower buds. I would suggest giving them a good general feed and mulch of well rotted garden compost next spring and make sure they don't go short of water and see if that helps

Thanks, I'll definitely give that a go.