June 5, 2014

Will Hydrangeas Bloom This Summer?



This mophead hydrangea at Ocean Beach was more than four feet tall last summer but shows barely a foot of new growth this week. The Beautification Committee will prune out all the dead stems shortly.
            The coldest winter in recent memory may be over, but its effects linger on in New London and surrounding towns. One of our most-loved landscape shrubs, the mophead hydrangea, was hit hard and is looking decidedly unlovely right now. This is the most familiar hydrangea, the one that is covered with large heads of blue flowers – the signature bloom of the shoreline.

            Most bigleaf hydrangeas were killed back nearly to the ground. Instead of being 4 to 5 feet of lush green by now, our hydrangeas are unlovely bundles of pale bare stems, with a few clusters of leaves near the ground.

The good news: the plants survived. The bad news: they likely will not flower this year.

            The most common varieties of this old-fashioned shrub flower on stems that grew last year. Because the buds died, the plants will probably be green mounds this year. The plants that don't flower this year will come back next year, unless we have two hideous winters in a row.

Many recent Mophead varieties flower on both last year's stems and this year's growth, so they will bloom, although later than usual. The biggest name in rebloomers is Endless Summer®. The flower heads are smaller and some folks find them less fabulous – but they bloom reliably, even in much colder parts of Connecticut than the shoreline. There is a whole line of branded Endless Summer® selections, widely available at good garden centers. Also look for 'David Ramsey' and 'Penny Mac', two  non-branded but very reliable rebloomers.

            So what should an unlucky gardener do? Start by trimming off the dead stuff. It may leave you with a very short plant, but those nude stems will never live again. Use pruners to remove the dead tissue, cutting just above a viable leaf. It's best to do this stem by stem, which may take a while, but is cleaner and better for the shrub than using power shears. If a stem or two winds up a lot taller than the rest, cut it back to a comparable height, always snipping just above a leaf.
           


            One of the Beautification Committee members, Cheryl Pappas, is a professional horticulturist and has a skilled hand with pruners. She reports she has found buds while working on sad-looking hydrangeas, so there may yet be good news!



            Go ahead and fertilize your hydrangeas too, spreading a few shovelfuls of compost around the crown. Or use a slow-release organic fertilizer such as Plant-tone, following the label directions. If the weather gets hot and dry, consider deep watering plants during drought. Then, alas, you'll just have to wait and see.

Alternate Hydrangeas

            Other, different species of hydrangeas came through the winter just fine. Panicle, oakleaf and arborescens hydrangeas all flower on new growth, so even the most vicious winter won't stop them. They bloom white or pink, however, not the true blue that is so appealing in mopheads.

            If you're considering replacing your hydrangeas or adding some new ones, here's a rundown.

Panicle Hydrangea

Limelight™ Hydrangea displays white flowers in August
'PeeGee' is the old standard Hydrangea paniculata, but the market is full of terrific alternatives. Limelight™ flowers open pure white, and the petals eventually fade to green, then tan. The bloom season is remarkably long, with plants looking good from July to October. Limelight™ gets to be BIG, easily 6 feet tall and wide in a few years, so site it with care. The flowers are terrific for cutting and for drying.

Other big, gorgeous varieties include 'Strawberries and Cream' and Pinky Winky™, whose colors vary from white to pink to wine over the course of a long bloom season.

Fortunately, breeders have also developed several varieties that are compact, reaching only 2-3 feet in height and width, while blooming prolifically. Look for Bobo™, Bombshell™ and Little Lime™.

Panicle hydrangeas can be cut back hard in late winter, to encourage more branching and blooming, but need little care once established.
By September, the flower heads of Limelight have turned green. Shown here with 'Kelvin Floodlight' dahlias

Oakleaf Hydrangeas

Native to the southeastern U.S. Oakleaf hydrangeas (H. quercifolia) also bloom on new wood and are reliable in Connecticut. The leaves have distinctive lobes, reminiscent of oak leaves (duh!) Flower heads tend to be elongated and open, gradually suffusing with pink and deep tones are they age. The foliage turns a vibrant burgundy in the fall and lasts until nearly winter. Oakleafs are more tolerant of shade, although they will bloom best with at least a few hours of sun.

There are a number of selections in the trade, but garden centers are likely to carry just one or two. Mature plants can be 6-8 feet tall and wide, but several dwarf varieties are also available.

Smooth Hydrangeas

H. arborescens used to be the only choice for gardeners in cold climates, if they wanted hydrangeas. The most common variety is 'Annabelle', with enormous pure white flower heads. They are the first hydrangeas to bloom in a normal season. Stems of all the smooth hydrangeas tend to be somewhat floppy, finding it difficult to support the oversize blooms. Typically, gardeners cut this type all the way to the ground in late winter.  

A couple of recent introductions are pink: Bella Anna™ and Invincibelle Spirit™. The individual florets are dainty but the heads are large. It does take several years for the smooth hydrangeas to deliver full-size heads, though. A delightful cut flower. 
Invincibelle Spirit™ is the soft pink flower seen in this mixed bouquet


Renée Beaulieu is a member of the New London Beautification Committee and a UConn Cooperative Extension Master Gardener who grows a lot of hydrangeas.

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