Q: I have 2 very healthy hydrangeas — ‘Bluebird’ and one Oakleaf hydrangea — that have grown in size over the last 7 years but do not produce blooms. This year the ‘Bluebird’ variety has lots of flower clusters but only 5 or 6 little white flowers bloom on each cluster. I have not cut it back in a few years since I was afraid I was cutting away the new growth and therefore the blooms. The plants are in an east facing garden against the garage wall. The soil tends to be lots of clay. Any suggestions on fertilizer or pruning?
A: ‘Bluebird’ is a selection of Hydrangea serrata. It’s called a “lacecap” hydrangea, because instead of producing flowers in big, rounded bunches like you’re probably used to, it bears clusters of tiny, blue fertile flowers surrounded by a single ring of larger sterile florets. Many people like the dainty look, but it’s not as showy from a distance as the more familiar type. This is just the way it blooms, so if you don’t like it, you’ll have to buy a snowball type, like ‘Nikko Blue,’ ‘Pennymac,’ or ‘Ayesha.’
The two main reasons oakleaf hydrangeas fail to bloom are either they get too much shade or someone prunes them in summer or fall. (They should only be pruned immediately after they finish flowering.) Neither cause sounds likely here, so it may be that your plant is an unnamed seedling, rather than a named selection, such as ‘Snowflake,’ ‘Snow Queen,’ or ‘Harmony.’ Named selections often bloom more heavily and at a younger age than seedlings do. All of the ones I mentioned are available in nurseries.