In a normal year, the hydrangeas would be thick with leafy growth and holding aloft conspicuous buds to open at month's end either as lacecaps or globes, thus introducing an effervescent spring to a more languid summer.

Hydrangeas are one of the most valuable shrubs in the garden, because the large individual petals are not true flowers but durable structures called rays. Their color may fade or change to subdued wines and mauves, but they persist ornamentally well into September.

This is not a normal year, as we have discovered. The polar vortex winter lives on in dieback, as plants we thought were safe emerge wounded from the cold, or do not emerge at all. The casualty list includes fig trees, some hybrid tea roses, camellias, loropetalums, rosemaries and a few crape myrtles, as well as a few more obscure evergreen shrubs.

A friend in Washington grew a sweet bay tree successfully for 29 years. It has appeared dead these past few weeks, but a couple of tiny shoots are emerging from its base. Most other sweet bays, I suspect, are what might be called totally dead.

The situation has generated a lot of reader correspondence, much of it related to the tatty state of the beloved hydrangea.

There are several kinds of hydrangea. The ones in question are derived from Hydrangea macrophylla or serrata, or both, and give us the classic mophead or hortensia type, such as Nikko Blue; the more demure mopheads of varieties such as Preziosa or Izu no hana temari; or the classy lacecaps, of which my favorites include Blue Bird and Blue Billow.

There is a popular variegated version of Mariesii, a lacecap, and every morning, Charlie and I check out three of them on our neighborhood stroll. Charlie is wondering how he might irrigate them (he's a dog), and I have an urge to take some pruners and remove all the naked twigs sticking up in a five-foot tangle above a ground-hugging clump of new growth.

This is the lot of hydrangeas this year. Although there are some years when unprotected new shoots are hit by a late frost in April, the wholesale zapping of bigleaf hydrangeas this year is a phenomenon largely unknown in these parts. Most of the Washington area is supposed to be in the plant hardiness zone 7, with the urban core in the warmer half of this zone -- meaning average winter lows between 5 and 10 degrees. This is supposed to be safe territory for hydrangeas.

Bigleaf hydrangeas bloom on wood that grew last year, so their dieback results in little or no flowering for a year. Not all of them were afflicted: The serrata hybrids, with the bloodlines of mountain hydrangeas, tend to be hardier than macrophyllas. A commercial grower in Northern Virginia told me he had lost five of 100 hydrangeas entirely but that 40 had their top growth killed.

In my garden, I had three named Lady in Red survive intact. They are budding now and looking great.

Carole Bordelon, who cares for the hydrangeas in the Asian collections at the National Aboretum, reports a lot of winter damage. In a typical year, she will remove a third of the old branches to keep the shrubs open and floriferous. This year, all the old top growth is coming off in those specimens with winter kill, to tidy the plant and allow the fresh growth to develop. In these specimens, there will be no flowering this year, but the grooming is all you can do other than give them a light mulch and make sure they get watered if it turns dry.

There are other wonderful hydrangeas unaffected by frigid winters: The oakleaf hydrangeas are now beginning to flower. Later, we will have the smooth hydrangeas and grandifloras of late summer and early fall, unbowed by a dark winter or the notion that the garden somehow shuts down by the end of July.

The widespread damage to the common bigleaf hydrangeas has been a boon to the growers and retailers of a new wave of reblooming versions of these hydrangeas. That is, they flower on wood that grew last year (if it survived the winter) but then rebloom in cycles on new growth through the season, much as a modern rose might. A bad winter hence won't wreck the next season's display, although it might delay it a little.

The first of these is called Endless Summer (which in a climate like ours sounds more of a threat than a promise). Once this reblooming trait had been discovered, it could be employed in developing other varieties. Blushing Bride, a white mophead, came next. Its owner, Bailey Nurseries, now has four in its series, subsequently adding the first reblooming lacecap, Twist-n-Shout, and a mophead named BloomStruck, valued for its sturdiness and heat tolerance.

Another plant brand, Proven Winners, has developed its own line of reblooming hydrangeas, five macrophyllas in its Let's Dance series, and two serrata types, including a dwarf named Tiny Tuff Stuff.

The newest introduction is Rhapsody Blue. "It's a third or fourth generation, so the reblooming is a lot stronger," said Shannon Springer, a spokeswoman for Proven Winners. Check with local garden centers for availability and variety. Next year, the brand plans to introduce what it says will be its best rebloomer, named Blue Jangles. "You'll see a huge difference in future generations."

This is all good news to hydrangea fans crestfallen about the polar vortex. I value these reblooming hydrangeas and grow them, but it would be a shame to turn our backs on all the older varieties out there, which have been cherished over the years for their diverse forms and colors and habits. I like robust old hydrangeas that get to six feet or more and as much in width, and are covered in early summer blooms that then fade as the season progresses. If we have one winter in 20 where they are beaten down, that's a price worth paying.