At the beginning of the 19th century, the geranium was a novel and beloved plant. Thomas Jefferson took some to the White House. By the end of the century, people were sick of it.

William Morris, the design genius who elevated the marigold to patterned perfection, found the geranium proof that “even flowers can be thoroughly ugly,” wrote Kasia Boddy in “Geranium,” a new cultural history of the flower.

Today, the geranium is still disdained by horticultural mavens, and yet some 150 million plants are sold each year to folks who rely on that splash of scarlet (or pink, white or salmon) to decorate their summer yards, patios and hanging baskets. Can so many people be so wrong?

No. My gardening buddies might believe that I’ve been smelling the citronella, but I think geraniums are okay. They just need to be used with restraint — don’t line the front walk with them — and given a little more TLC than most get.

Survives summer

The same stiffness that some find vulgar gives the annual an architectural quality, the classic type stands up well to the heat of summer, and the blooms appear all season long to attract butterflies and hummingbirds.

If you are not convinced, there is a new reason to like this plant urchin: The breeders who work on annuals have made a major breakthrough in recent years with a new class of geranium (or pelargonium, if you are a purist) that will provide new forms, new colors and better performance by crossing ivy-leafed geraniums with zonal types.

These novel “interspecific” geraniums “perform spectacularly well in all sorts of terrible weather stress,” said Allan Armitage, a floriculture expert at the University of Georgia.

Different varieties

Zonal geraniums are the classic stubby, large-leafed plants with darker zone markings on the foliage and large flower clusters on long stalks. Ivy-leafed varieties are compact trailers that smother themselves in blooms, making them a favorite for hanging baskets and window boxes.

Interspecifics combine the heat tolerance of zonal geraniums with the superior performance (and in some varieties, the look) of ivy-leafed geraniums. The “ivies” preen and strut in places like California and Switzerland, but the heat and humidity of other regions is not kind to them. Once night temperatures rise to the low 70s, they flower grudgingly if at all and generally go downhill.

The new hybrids overcome this problem, giving gardeners healthier-looking geraniums with as many as a third more blooms than zonals.

Since a company named Goldsmith Seeds introduced the first seven years ago, other hybridizers have been scrambling to produce their own.

Creating hybrids

The company, based in Gilroy, Calif., was later acquired by Syngenta Flowers. The hybrids are now widely available at garden centers and mass merchandisers — look for “interspecific” on the label — and more are on the way.

The inventor is a hybridizer named Mitch Hanes, who has been breeding new geraniums since 1987. Others had crossed zonal and ivy-leafed geraniums before, but the resulting seedlings were inherently feeble. His introductions were the product of a lot of genetic refining through additional cross-breeding, he said.

His Caliente line was introduced to consumers in 2006, the Calliope series of varieties in 2010.

“The dilemma is that we are in a commodity market,” he told me. “How do you differentiate so people at the garden center instantly see that it is different?”

He thinks he has achieved that “especially with Calliope Dark Red. It’s a variety you can recognize from a quite a distance.”

Proven Winners is moving next year to introduce its own branded lines, each with five flower colors. One is called Boldly, whose hues range mostly in the reds, the other Timeless, which includes lavender, orange, pink and red varieties. The Boldly varieties share the more zonal, upright traits, the Timeless ones the trailing habit of the ivy-leafed, said spokeswoman Jeanine Standard.

Ball Horticultural in West Chicago, Ill., next year plans to introduce a new line of double-flowered interspecifics named Double Take, Jim Kennedy said. He is sales manager for Ball FloraPlant, a breeding subsidiary that developed the new line with a German-based partner, Selecta.

Global breeders

Ball, Syngenta, Proven Winners and others are part of a huge and complex global industry of plant breeders, propagators, growers and retailers that have tapped into consumer interest in container gardening. Their target consumer is not an experienced gardener but someone who wants annuals as colorful, floriferous and easy seasonal decoration. The geranium is a key player in this world: Among annuals that are vegetatively propagated (as opposed to seed-grown), geraniums “are top of the heap,” Kennedy said.

Rick Schoellhorn of Proven Winners said the hybrids make geraniums available to Southern gardeners, increasing the plant’s range by about 30 percent. “The rest of the country gets a tougher, more disease-resistant plant and a better color range,” he said.

This includes a deep purple red coloration that before was only in the ivy-leafed varieties.

The new hybrids may well make hanging baskets more popular in hotter regions once more. When homeowners used them for ivy-leafed geraniums a few years ago, the plants would burn up, Kennedy said. Consumers came to see the hanging basket as a losing proposition. “I could see in terms of hanging basket applications in New England and the mid-Atlantic, ivy-leafed geraniums coming back, given the heat tolerance we are breeding into them.”

The new line was developed to capitalize on the ivy-leafed traits of glossy foliage, clean presentation and high flower count, but also for the longevity of the bloom, he said. Another key trait, along with the rich crimson flower hues, was dark green leaves, which buyers equate with plant health.

“The pelargonium instills confidence in the gardener, especially the new gardener,” he said. “That breeds success; they are going to come back next year for more.”

Fragrant flowers

Scented geraniums are considered herbs and are derived from several species. They are less showy than zonals and ivy-leafed, with blooms that are small to minute. But individual plants can get considerably larger, to three feet or more. Others might get to just 12 inches. They are grown for their foliage ornament and, particularly, the scented oils that they contain. Over four centuries, breeders have developed dozens of varieties that mimic the fragrance of other plants. They include lemon, lime, orange, pineapple, eucalyptus, peppermint, rose, apple and various mints. Some scents are more convincing than others. The leaves have a range of culinary uses, and fans put them in jellies, salads, summer drinks and tea, and incorporate them into cakes. The variety known as Citronella produces an oil that is said to repel mosquitoes.

The foliage ornament is highly variable in form and size and includes cutleaf and variegated types. They are best grown in clay pots and can be brought indoors for winter, if you have a bright room or windowsill.

This year I’m growing eight of them, including the popular, some say essential, Attar of Roses, a big plant that needs pinching back. The lineup includes another robust variety named Peppermint Rose, whose lavender flowers have a minty-rose flavor and scent, and a striking cutleaf variegated plant named Grey Lady Plymouth, also with lavender flowers. Apple is a more compact variety whose aroma is, to my nostrils, unconvincing, but it has tiny umbels of white flowers that invite close examination.

Another class of geranium — the Regal Geranium — suffers in the heat and could be considered only a fleeting spring extravagance, along with such cool-climate plants as primulas, fuchsias and Gerbera daisies. This is unfortunate, because it is a lovely and elegant geranium with striking, bicolored blooms. As a class of geraniums, regals are on the wane as small, specialty growers go out of business.

Robin Parer, a grower north of San Francisco (, maintains one of the best collections in the country, along with a wide range of scented geranium varieties. She also sells the true geranium, a hardy perennial also known as cranesbill.

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