In the never-ending horticultural competition for best flowering shrub, hydrangeas consistently take the top prize. No other family of flowering shrubs can compete with hydrangeas for their beauty and versatility. Gardeners are the big winners: For every garden, there is a hydrangea -- or three.

Hydrangeas are natural problem-solvers. They make a great impression when they're planted in billowing waves across the front of a house. They're magnificent specimens on their own. They fill a small garden with luxurious, long-lasting blooms, and they are grand enough to more than hold their own in a big garden. They're also extremely handsome in pots. And, if you can bear to pick them, their flowers are gorgeous in bouquets.

The challenge is deciding which ones to grow. In the past couple of decades, dozens of ever more colorful, hardy, hardworking new hydrangeas have been introduced. These new varieties tolerate steamy summers and cold winters, bloom for months and need no pampering.

Hydrangeas are almost the essence of summer. The original Endless Summer hydrangea -- a blue mop-head flowering variety known for its long blooming period, from early summer through fall -- was introduced in 2004 and was an immediate sensation: 18 million plants were sold in its first seven years on the market. Since then, three more hydrangeas have been added to the Endless Summer collection: Blushing Bride, a white-flowering variety; Twist-n-Shout, a variety with delicate lace-cap flowers; and BloomStruck, which has deep blue blooms. This year, they are joined by Summer Crush, which has luminous raspberry-colored flowers on a compact plant.

Endless Summer hydrangeas are bred to last. They flower both on new shoots and on the previous year's growth, so their first flowers open earlier and their last ones bloom later than most hydrangeas on the market. Their hardiness also sets them apart from any previous summer-flowering hydrangeas, but in the coldest climates, planting them in protected spots is still a good idea.

As gardeners have rediscovered the pleasures of mop-head hydrangeas, hybridizers have broadened the selection of panicle-blooming hydrangeas, too. Panicle hydrangeas tend to bloom a little later in the summer, their cone-shaped flower heads covered with hundreds of tiny white or cream-colored blooms that fade to pink. They adapt gracefully to sun or part shade, and they are both heat-tolerant and bone hardy, surviving without protection even in bitterly cold climates. Limelight, perhaps the best known of the new generation of panicle hydrangeas, grows up to 8 feet tall and blooms prolifically. A dwarf form, Little Lime, has all the hardworking characteristics of the big shrub, but only grows to be 3 to 5 feet tall. Bobo, even smaller and perhaps more floriferous, is only 3 feet tall and wide.

"They're eye-catching," says Noelle Clark Akin of Petitti Garden Centers in northeast Ohio. The company has nine shops, and hydrangeas are the top-selling flowering shrub at all of them. Petitti Garden Centers carry 40 or more different hydrangeas, and last year, Bobo and Little Lime outsold even Endless Summer, Akin says, although not by much.

The selection doesn't stop there. Breeders have been working to improve the flowers and performance of smooth hydrangeas, which are North American natives. (They are also called Hydrangea arborescens.) New varieties have bigger flowers and sturdier stems than the original species, and a refreshing splash of color: Several new smooth hydrangeas -- Invincibelle Spirit and Invincibelle Mini Mauvette among them -- have big pink snowball flowers rather than white blooms. Arborescens hydrangeas are heat- and cold-tolerant, blooming in full sun or part shade.

When customers come to a garden shop looking for hydrangeas, they usually go out with "whatever looks best the day they come in," says Ron Meadows, the buyer for the nearly two dozen Meadows Farms Garden Centers in Virginia and Maryland. Limelight and Little Lime are among the most popular with Meadows Farms retail customers.

Garden designers go beyond the crowd favorites, Meadows says, and often include oakleaf hydrangeas in clients' gardens. These hydrangeas have large, leathery leaves, rather like big red oak leaves. The plants bloom in early summer, with loose, white panicle-type flowers. In fall, the foliage turns deep red. When the leaves drop, the plants' stems, with naturally peeling bark, are particularly decorative through the winter.

"Oakleaf hydrangeas don't show very well in the garden center, but I love them in the landscape," Meadows says. They can grow to 8 feet tall or more, but dwarf varieties are perfect for small gardens: Munchkin and Ruby Slippers both grow to only 3 feet tall.

Choosing among the types, colors and sizes of hydrangeas at a garden shop in spring can be overwhelming, Meadows admits. "We need to streamline," he says. But until that happens, if you come home with more than one hydrangea, you have an excuse: You've just started a collection.

SOURCES

-- Endless Summer hydrangeas have their own website, endlesssummerblooms.com

Gardening under trees can be frustratingly difficult. A tree's blissful shade limits the selection of plants gardeners can grow, though weeds never seem to have any trouble moving in. But if you work at it, you can have a beautiful, healthy tree and a lovely shade garden, too.

Instead of trying to fight the naturally shady conditions under trees, take advantage of them, says Linda Chalker-Scott, an extension specialist and professor at Washington State University. A simple ring of mulch that extends out to the drip line (the outer edge of a tree's canopy) will make your whole garden look sharply manicured and benefit your trees tremendously, Chalker-Scott says. In her own garden, she puts down a generous 8-inch layer of mulch every year, but her rule of thumb for home gardeners is a 4-inch layer, which is enough to keep annual weed seeds from germinating in the soil under trees.

A ring of mulch gives a clear a signal not to cut across the yard or park too close to trees, so it helps reduce soil compaction. A generous layer of mulch also provides nutrients to trees as it decomposes. Mulch provides a habitat for beneficial insects and microbes, and it reduces the need for herbicides and fertilizers. Mulch can be free, too: Chalker-Scott advocates using "arborist mulch" from tree-trimming crews. Often, all you have to do is ask tree-trimmers to drop off their wood chips in your driveway.

Arborist mulch is usually fairly coarse, with chips no less than about half an inch in diameter, to allow air and water to move through. Don't worry, Chalker-Scott says -- this mulch will not suffocate roots or invite termites to invade your property. For the health of your trees, place mulch around them in a donut shape, not like a volcano, she says. The mulch ring should have high outer edges and taper down to a thin layer around the trunk in the center.

A sweep of grass under a tree isn't out of the question -- but you have to be realistic. "You can definitely grow grass under a tree, just not a manicured turfgrass," Chalker-Scott says. "A mixture is better than monoculture," she says. Instead of trying to plant bluegrass, rye, fescue or any other single-turf species under a tree, look for a grass mixture formulated for shade, which will weather conditions under a tree without looking scruffy. Make violets and clover welcome, if they appear, and set your mower's cutting height up a bit -- in shade, grass will naturally grow a little taller than in bright-sun conditions.

To give turf under shade trees a chance to grow and thrive, avoid walking on the grass. If it simply never flourishes and you find you need to plant fresh seed every year, try another approach.

Low-growing groundcovers, such as liriope, ajuga, violets and pachysandra, are all well-suited to the dappled light under the canopy of trees. Groundcovers chosen for your climate and conditions are easy to establish and will not compete aggressively for the water and nutrients in the soil. They also protect tree trunks from mowers and string trimmers, which Chalker-Scott calls "instruments of doom" for your trees.

If a path through your garden leads through an area with trees, a bed of gravel and a series of stepping stones will direct traffic and limit soil compaction. Mulch or groundcovers on either side of the path will give the area a tailored look.

Mature trees are garden treasures, and they deserve special recognition. A luxurious ring of mulch around a large tree might not be feasible, and a dense canopy may make it impossible to grow even the most shade-tolerant groundcovers. In such a situation, a handsome garden bench or a tree seat custom built around a great old tree will transform the scene. From the house, the quiet tableau will invite you out, even if only in your imagination, every time your glance falls on it. And when you are out in the garden, a bench under a tree is the perfect place to escape from the sun and set your tools down for a moment, a spot where you can linger and listen to the wind and the birds and forget about the busy world in the bright sun outside.

SOURCES

Linda Chalker-Scott is the author of "The Informed Gardener" and "The Informed Gardener Blooms Again." She is a host of the Garden Professors blog (gardenprofessors.com), which explores the science behind garden myths, and a horticulture professor at Washington State University.

Perennial plants, the classic stars of good gardens everywhere, aren't quite what they used to be -- they're better, and they are becoming more important. Popular perennials introduced recently are setting new standards beyond their good looks, toughness and reliability. They are defining the role of gardens in our lives.

"The classic perennial plants I rely on are drought tolerant, and they attract pollinators and provide nectar for bees and butterflies," says Janet Draper, horticulturist at the Mary Livingston Ripley Garden at the Smithsonian Gardens in Washington, D.C. "It's not just about me anymore," Draper says. These days, pollinator-friendly plants are being prioritized more highly than ever.

Habitat loss has put increasing pressure on insect populations, and gardens that attract pollinators help make up for the loss of wild nectar-rich plants that bees, butterflies and other pollinators depend on. Perennial plants, which, once established, come back every year -- usually bigger and stronger than the year before -- can be the backbone of a hard-working, long-blooming, pollinator-friendly garden.

One of Draper's favorite perennials is Calamintha White Cloud, "a bee's dream," she says, "for bees of all stripes -- from the little tiny guys to honeys and bumbles, all happily buzzing along all summer long." This plant makes gardeners happy, too. "It's a blooming machine," she says, a hardy, low-maintenance perennial that doesn't need pruning or pampering and isn't bothered by pests.

Draper is also the president of the Perennial Plant Association, and her list of favorite new perennials is long. She likes to pair the billowing White Cloud calamintha with the purple globe flowers of Allium Millenium, which is the PPA's plant of the year for 2018. She combines these two with the long-blooming Phlox paniculata Jeana, which was a stand-out in trials at Mt. Cuba Center, a botanical garden in Hockessin, Delaware. Jeana, which has pink flowers on 5-foot stems, blooms from July through October and attracts more butterflies than any other phlox. Draper calls the combination of Jeana phlox, Millenium allium and White Cloud calamintha "a pub for bees. They all like to hang out at the local pub," she says.

Brent Horvath, a hybridizer and the owner of the wholesale nursery Intrinsic Perennial Gardens, also gives high marks to summer-blooming alliums. His favorite is one of his own introductions, Summer Beauty, which begins to bloom in July in his garden in Illinois. He likes Summer Beauty for its flowers and for its long-lasting seed heads, which look great with little caps of snow in the winter. True classic perennials "have presence in the garden for four seasons," Horvath says.

Horvath and Draper are both smitten by perennials that contribute interesting textures to a garden, and ornamental grasses fill that bill with aplomb. Fountain grass, Red Head (Pennisetum alopecuroides Red Head) blooms a month earlier than other fountain grasses, Horvath says, with showy flower heads 8 inches long and 4 inches wide. When they're back-lit by the sun, they seem to glow. The abundant foliage of Hakon grass (Hakonechloa macra Aureola) brightens shady spots and "gives the feeling of flowing water," Draper says. She also relies on the vertical habit of reed grass (Calamagrostis Karl Foerster) for dramatic punctuation in the garden.

Durability, availability and performance year after year are the qualities Horvath insists on for classic perennials. Black-eyed Susans (Rudbeckia) come close, but many varieties are susceptible to foliage diseases. A new Rudbeckia called American Gold Rush has narrow leaves that resist disease, he says. The plants produce golden-yellow flowers with a distinctive dark center from mid-summer through frost. They thrive in the heat and humidity of the south and survive brutal winters in the north.

Reblooming and long-blooming perennials are the new standard, says Karl Batschke, product manager for Darwin Perennials, the company that introduced the colorful Sombrero series of coneflowers. Gardeners want their perennial flowers to bloom all summer long, just as many annual flowers do, "and we are getting closer and closer to that," he says. "There is a lot of cool new stuff coming along," including daisies (Leucanthemum) that bloom for three months and a summer-blooming candytuft (Iberis). New perennial lavenders and salvias on the market are good-looking, hardy and long-blooming, and pollinators find them attractive, too, Batschke says. "I grew up with annuals," he says, "but what I see now in perennials coming to market -- there's diversity and beauty, and they're all exceptional pollinator plants."

It appears that butterflies and bees are the beneficiaries of the latest perennial-plant introductions, but consumers can't complain. When new plants promote biological diversity and also knock your socks off with fabulously long bloom times and performance year after year, gardeners hit the jackpot.

SIDEBAR

More New Classics

Look for these other great new perennials, too:

Janet Draper, president of the Perennial Plant Association (perennialplant.org) and horticulturist at the Mary Livingston Ripley Garden at the Smithsonian Garden (gardens.si.edu) in Washington, D.C., says she is "moving beyond old-fashioned perennials" that only bloom for a short time. She recommends:

-- anise hyssop (Agastache) of all kinds. Blue Fortune is a long-blooming variety that attracts many pollinators.

-- lavender, especially Phenomenal, which thrives in heat and humidity.

-- bluestar (Amsonia hubrichtii), with blue flowers in spring and bright yellow foliage in fall.

-- Oak sedges (Carex), a clumping grass for sun or shade. There are "so many to choose from," she says. Her favorites are C. oshimensis Evergold, Everest and Everillo.

-- Itoh hybrid peonies, which are a cross between herbaceous peonies and tree peonies. The plants are prolific early-spring bloomers with larger and showier flowers than traditional garden peonies.

Brent Horvath, owner of the wholesale Intrinsic Perennial Gardens (intrinsicperennialgardens.com) in Hebron, Illinois, has a few favorites among his own introductions:

-- Geum Mai Tai is a durable, reliable, reblooming geum with handsome antique-gold flowers. They are great in Hardiness Zones 4 and 5.

-- Shasta daisy Daisy May, a vigorous, reblooming daisy that grows to about 20 inches tall and blooms all summer long.

-- Sedum Pillow Talk, which has five-inch flowers that stand tall on 20-inch stems. Bees and butterflies love it.

-- Big bluestem (Andropogon) Blackhawks and Red October are tall, hardy ornamental grasses with dramatic fall color.

Kelly Norris, director of horticulture and education at the Greater Des Moines Botanical Garden (dmbotanicalgarden.com), is a big fan of ornamental grasses. He recommends these new classics:

-- Sun King aralia, a shade-loving perennial, for its lush, golden foliage on plants 3 to 6 feet tall.

-- Little bluestem (Schizachyrium scoparium) Standing Ovation is a drought-tolerant prairie grass, "a workhorse" for its foliage, Norris says.

-- He also likes oak sedge (Carex pensylvanica), an ornamental grass that grows just 8 to 10 inches tall. "It's a poster child for the genus," Norris says. "Gardeners are considering plants that maybe just aren't all about flowers," he says, and this shade-loving groundcover deserves more attention.