What in the world is
happening to petunias? Supertunia? Tidal Wave? Surfinia? It wasn't
that long ago that there was one kind of grandiflora. Summers
flowerbeds were filled with large, deep throated, velvety blooms
with bold color. At night they wafted a light, sweet fragrance.
When I sharpen my focus, I also recall certain imperfections:
constant deadheading and, after a rain, that unsightly wilted
look.
Our old-fashioned favorite
is the subject of intense research in the laboratory and the field.
The tinkering actually began a long time ago. The first petunia
came from South American more than two centuries ago, where more
than 30 species were found. Two of those species‹white Petunia
axilliaris (previously known as P. nyctagiflora)
and the magenta Petunia integrifolia (P. violacea) were
crossed to produce the garden petunias we know as P. x hydrida.
Petunias belong to
the Solanaceae or nightshade family, keeping company with tomatoes,
peppers, potato (including Ipomea, the chartreuse sweet potato
vine now in vogue), and Salpiglossis, which the early petunias
closely resembled.
As early as the beginning
of the nineteenth century, European breeders saw petunia's potential
and were experimenting to develop larger flowers and more colors.
In the 1950s the first red petunia came on the market. The first
yellow petunia followed in the 70s.
For the last couple
decades, breeders, including Suntory Ball Seed, Pan American Seed,
and the Floral and Nursery Plants Unit of the U. S. National Arboretum,
have worked feverishly to add a wide range of colors, new flowers,
and forms, as well as weather tolerance.
One such effort is
Dr. Rob Griesbach's, who is with the U.S. National Arboretum's
Research Unit. He went to work crossing P. integrifolia
with P. exserta, which is a woody shrub with bold red flowers.
However, P. exserta's flowers are small and star shaped.
It's also very hairy but the worst of it is that the hairs smell
bad, are sticky, and collect dirt. After continuous backcrossing
to P. exserta, and selecting for its hairless aspect and
larger flowers, Dr. Griesbach now has a 'line' of petunias that
have large red flowers and no hairs. I can't wait to see a red
flowering petunia shrub in the nursery.
In all this experimentation,
about the only things that haven't changed are the plants' need
for plenty of sun and fertilizer. Obviously there's a lot of trial
and error in this experimentation. (I worry that some mutant will
escape the lab and we'll have a petunia kudzu taking over the
Everglades.) The success stories are obvious. Look at the garden
centers where you'll see a bounty of colors, flowers, forms, and
plants that even offer weather resistance. My first encounter
with the new generation of petunia was the Wave. But it wasn't
until I came across a Supertunia (which at the time I thought
was a joke), that I realized petunias were being reinvented before
my eyes.
Where do all these
new cultivars fit in? Not to worry, we still have grandifloras
and multifloras. The line between the two, however, is becoming
hazy as new hybrids offer characteristics of both: weather resistance
and numerous blooms. One approach is to put the intermediate-sized
cultivars in a new category called floribunda. What follows is
my attempt to make sense of it all, sidestepping an intermediate
group and leaving new cultivars in the category they most resemble.
The small cultivar, Fantasy, necessitated the creation of the
milliflora category, as do
the new vigorous trailers like Wave and Surfinia.
Grandifloras
are what most think of as petunias; large-flowered petunias consisting
of both single and double flowering forms. Single grandifloras
produce generous-sized blooms up to five inches across. Some single
varieties have ruffled or fringed petals. Others possess a trailing
habit which make them ideal for window boxes and hanging baskets.
The large flowers don't usually hold up well during rainy weather
(but that's changing for some cultivars, see below) and often
become unkempt and straggly by late summer. Most do best in cool
weather. Varieties include Supercascade, Supermagic, Ultra Star,
Falcon, Daddy, Picotee, Pirouette, Prism, Razzle Dazzle. Note
that Ultra Star, Supercascade, and Storm are said to represent
a significant step forward in weather resistance.
Multiflora petunias
have smaller flowers (one to three inches across) in greater numbers.
There are both single and double flowered versions. The plants
and flowers are generally compact and performance in hot or wet
weather is better overall than for grandifloras. Of late, resistance
to wet weather has been improved, according to one report, by
selection of plants with a waxy epidermis that sheds the rain
from the petals. Varieties include Celebrity, Duos, Primetime
(Primetime 'Summer Sun' has true-yellow flowers), Carpet, Delight,
Madness.
Milliflora is a category
created specially for Fantasy petunias, a cultivar introduced
in 1996. Expect compact miniature plants two-thirds the size of
a normal petunia. Actual height and width is six to eight inches
with flowers that are an inch or so across. It takes several to
fill a medium-sized pot and are best used in containers rather
than flowerbeds.
Calibrachoa Million
Bells also belongs in this group because of its diminutive size,
although it is a trailer. It isn't a true petunia but looks like
one and is treated like one. It's a small and compact plant with
flowers that are less than one inch across. (See the May
Garden Edition for more information.)
Vigorous trailer is
the category that fits newer cultivars like Surfinia, Wave, Supertunia,
and Tidal Wave Hedgiflora. To varying degrees, all have a cascading/prostrate
habit.
Surfinia petunias are
the ones you see in Europe, cascading in sheets of color from
window boxes. They are recognizable by a distinctive veining pattern
in the blooms.
Wave excels as a carpeting
groundcover in a good sized area. Plant on two-foot centers. Purple
Wave is very low growing (four to six inches tall) with magenta
flowers that are two inches across. Pink, Rose, and Misty Lilac
Wave are more upright (six to eight inches tall) with slightly
larger blooms. Supertunia is a vining (but not climbing) petunia
that needs plenty of room to cascade. It's more aggressive than
Surfinia. Flowers are three to four inches across.
Tidal
Wave Hedgiflora is the 'hedge' type of petunia that, when planted
closely, say one foot apart, can grow into a dense, mounded mass
16 to 22 inches tall. Grown in a restricted space with supports,
it will grow an extra two to three feet upward, like a vine.
Happy planting!
