If I said August is hydrangea time, any of you more learned gardeners would take umbrage and say no. We all know, you would claim, that hydrangea time is late spring and early summer, not late summer and/or autumn. 

You would be right, but so would I. There are hydrangeas, and there are hydrangeas. The common bigleaf, or French, hydrangeas, do indeed flower in spring, if they flower at all. This year they largely did not, because of oddball late fall and late spring freezes, which decapitated their tender buds. These are the old-fashioned blue ones found around every old homestead thither and yon. 

Other hydrangeas, largely white ones, have been waiting in the wings to enrich our lives, starting in July and continuing into August and even September. These are the paniculata varieties of, naturally, the species Hydrangea paniculata. They are a horse of another color from the spring ones. 

White flowers in the horrid heat of our late summers are just what the doctor ordered for a cooling effect, and that is what the paniculatas offer. Some of them started back in June and continue as we speak, while others are just breaking and still others are yet to go.

Among the first of them, starting in early July, are brothers, ‘Limelight’ and ‘Little Lime.’ They are pretty much identical but for a great variation in size, ‘Limelight’ growing to maybe 10 feet without pruning and ‘Little Lime’ no more than half that. The big brother has flower panicles that sometimes reach to a foot across, while, again, little brother has panicles half that size. The bodacious panicles of ‘Limelight’ sometimes lead to flopping when their heads are soaked with rain. 

A great feature of paniculata hydrangeas is the fact that they bear mostly on new wood of the year. If a smaller plant is wanted, the stems may be cut back to a foot from the ground in early spring just as extension growth sets in, and, after they grow to another foot or so, they can even be cut in half again, but not after early June. Each cut will result in at least two or three branches, which means more flowers of a smaller size. Result: less flopping. 

Other similar varieties include ‘Phantom,’ which bears enormous heads of bloom and which can be given the chopping mentioned. Another one about the size of ‘Little Lime’ is ‘Bobo,’ which might reach 5 feet even with no pruning, but is better with the mentioned chop. 

Just starting as we speak is ‘Tardiva,’ a moniker appropriate to its “tardy” season of bloom. I had a patch of six of them in our lower garden for years that reached some 12 or 15 feet tall with trunks three inches in diameter. Relentless drought in three out of four years did them in, alas, and they were replaced by ‘Phantom,’ that flowers a little earlier, which I did not really want. I had nearby five of the ‘Lime’ series that filled that time frame and I really preferred in this case later flowering, but when I needed them I could not find any on the market. 

There are numerous other paniculata hydrangeas, some that fade to pink as they age and others with slight variations from white. All of these, however, are not reliable in these changes in hot climates and remain mostly white where we are.

A caveat with paniculata hydrangeas: they need a lot of sun to flower well. While the early blue hydrangeas will flower in deep shade, the white paniculatas prefer much sun. I was ignorant of this early on and planted several in shade, and they never bloomed until, in one area, the great storm (a tornado) of 2019 opened a big hole in the overstory in our woods, allowing more sun in. This year a few in that area bloomed with some aplomb.

 

JIMMY WILLIAMS is the garden writer for The Post-Intelligencer, where he can be contacted on Monday mornings at 642-1162.

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