Every year, National Garden Bureau names one edible, one
annual and one perennial as featured crops for a year.
2014 is the Year of the Petunia.
NGB, along with our members, provide
these tips about an annual flower enjoyed by many. Over 100
petunia images from our members can be found on the NGB website or in a
Year of the Petunia presentation on Slideshare.
What’s not to like about petunias? These incredibly
versatile plants come in an abundance of sensationally bold colors, are
widely adaptable, vigorous, self-reliant and largely pest and disease
free. They are low maintenance and drought tolerant, widely available,
are a great value, sport a variety of forms and colors, and some even
exhibit a light, sweet fragrance. Additionally, these fail-proof,
tried-and-true beauties are easy to grow, bloom ceaselessly from late
spring to fall and settle in comfortably whether planted in gardens,
trailing from containers or spilling out of hanging baskets. They’re
beautiful, desirable and completely irresistible to butterflies,
hummingbirds and gardeners alike. Thanks to new, fashionable shapes and
attractively colored blossoms, the petunia is still one of the most
popular summer flowers. In short, the perfect go-to gardening friend
for sunny places.
History - Then
Though generally treated as annuals by most gardeners, technically they
are tender perennials and are members of the potato family of plants.
Today’s feisty hybrids are the descendants of two lanky, tiny-flowered
South American species: the buff-white flowered Petunia axillaries and the night-fragrant,
lavender to purple-flowered Petunia violacea. First
discovered in South America in the late 1700’s these wild varieties
quickly captured the imaginations of European breeders who began
crossing them in search of the perfect petunia – a plant with large
beautiful flowers in a variety of colors.
Following the end of World War II, the transformation in the quality of
petunias came with the development of the F1 hybrids. Weddle, one of
the founders of PanAmerican Seed Company, won an AAS award in 1949 for
the first F1 single-flowered multiflora, ‘Silver Medal’ and in 1952
crossing a grandiflora with a multiflora producing a F1 vigorous
grandiflora hybrid ‘Ballerina.’
History - Now
A whole new world opened for petunias and their breeders with the
development of the F1 hybrids. This made it possible to regulate their
growth from the open, floppy forms to a bushier type with better
weather resistance, an increasing range of colors and
color-combinations and a far superior ability to weather the rigors of
As is quite obvious, in recent years the world of petunias has become a complex world,
for there are – literally – hundreds of named petunia varieties. But a
bit of advice for pairing the right petunia with your gardening needs
can be summarized, in part, in the following manner.
large-flowered blossoms (4-5”) consisting of both single- and
double-flowering cultivars form mounds of colorful solid, striped,
deeply veined, variegated or edged in a contrasting shade called
picotee. Grandifloras prefer a cool, dry sunny environment in protected
areas and dislike hot, wet or windy conditions, and work well in both
containers and beds.
compact plants with smaller (1.5-2”) flowers than the grandifloras;
however, they bloom prolifically and freely all season long. These
plants have single or double flowers and are available in a rainbow of
colors, often with contrasting centers or stripes. Bred primarily for
the wetter climates these petunias perform admirably in adverse weather
conditions especially during very hot or very wet spells.
(1-1½”) blossoms produced with wild abundance that cover the plant with
beautiful vibrant colors. Perfectly suited to containers, hanging
baskets, miniature gardens and as edging plants, these delicate
beauties bloom earlier, do not stretch, add fullness and contrast of
size and color when combined with larger blooming plants.
plants only (4-6”) in height that can spread up to 5 feet across. These
are fast growing plants with excellent heat and drought tolerance,
require very little maintenance, and make excellent flowering ground
covers. Their greatest popularity lies in their wild profusion of
blooms that tumble out of hanging baskets, window-boxes and tall
containers from late spring well into late fall in milder and warmer
Hedgiflora – one
segment of Spreading: have growth habits based on how
closely the plants are spaced in the garden. Grown close together, they
form a dense, mounded hedge from 16 to 22 inches tall. Grown in
restricted space with some support, they act like vines growing upward
an extra 2 to 3 feet. But when given plenty of space to roam, they make
a floriferous groundcover spreading 2½ to 3 feet.
Floribunda: an improved
multiflora petunia bred to have larger single- and double-flowered
varieties that bloom earlier while producing an abundance of flowers.
Like the grandifloras, they flower earlier, yet tolerate both hot and
wet periods, perking up quickly after every rain shower. Floribundas
are a fantastic selection for mass plantings in the landscape, and for
container plantings in pots and hanging baskets.
a combination of the best characteristics of the
petunia and calibrachoa plants. The Petchoa ‘SuperCal’ plants deliver
unique colors, sturdy blossoms and non-sticky foliage to overflowing
For growing and planting instructions,
read the full Petunia Fact Sheet here.
Petunia Maintenance Petunias don’t require a lot of care,
but they do benefit from some attention. During dry weather, a deep
watering once a week should be sufficient for petunias in beds and
borders. Plants in containers, hanging baskets and window boxes will
need to be watered when the soil surface becomes dry – on extremely
hot, sunny days that could be daily – and fertilized every couple of
weeks with a dilute fertilizer solution.
Always check the cultural tags that come with the purchase of your
plants. Many of the new cultivars are bred for compactness or mounding
and require no pinching back or deadheading. Your cultural tags will
give you this information. But as a general rule, to encourage
additional blooms and improve plant appearance, remove the spent
flowers on grandiflora and double petunias. This not only keeps plants
blooming longer, it also keeps plants looking fresh, healthy and well
groomed. The smaller flowering types, such as the milliflora and
spreading petunias are self-cleaning and don’t require deadheading. And
although it isn’t practical to deadhead sweeping stands of petunias in
the garden, it’s advisable to do so for plants in containers. After
pruning, fertilize and water the plants to promote new growth.
Today’s newer cultivars are pretty much disease-resistant, but as with
all plants, a few problems can develop and you will want to deal with
them as soon as possible.
Newly germinated seedlings can fall prey to damping off, a fungus that
attacks at the soil level and is irreversible. The young seedlings will
wilt and die almost overnight. Avoid damping off by using a
commercially available soilless mix and use only clean, sterilized
containers for starting seeds.
Young plants are susceptible to Botrytis, a fungus that is also
soil-borne and spreads quickly from an infected plant to a healthy one.
It thrives in cool, moist conditions, forming a powdery mold on stems,
leaves and flowers. Watering only early in the morning, avoiding
overhead irrigation and keeping plants spaced for good air circulation
are all good ways to avoid these problems.
Petunias are also susceptible to various viruses which can leave
foliage stunted and deformed with discolored and deformed flowers. The
safest control is to remove and destroy diseased plants and keep aphids
and other insects which can transmit the disease off the plants by
hosing the plant with a strong blast of water.
Petunias in the landscape can be bothered by different pests: flea
beetles which eat holes in the leaves of the plants and the small,
green budworm caterpillar which attacks plants in late June and July
and feeds on the flower buds. Usually, you won’t see the actual
caterpillar, but you should notice small black droppings and tiny holes
in leaves. If you have a major infestation, apply Bt (Bacillus
Petunia plants may look limp and scraggly after a hard rain; however,
the newer cultivars usually perk up within hours. Most petunias have
naturally sticky leaves and stems (some of the newer cultivars have
this trait bred out of them), so don’t panic and think this condition
is disease or pest related.
The National Garden Bureau recognizes and thanks Betty Earl as author
of this fact sheet.
The petunia fact sheet is provided as an educational service of the
National Garden Bureau. There are no limitations on the use. Please
credit the National Garden Bureau.
Please consider our NGB member companies as authoritative sources for
additional information. Click on direct links to their websites by
selecting "Member Info" from the menu on the
left side of our home page. Gardeners looking for seed sources can
use the “Shop Our Members” feature at the top
of our home page. Photos can be obtained from the NGB website in the
area labeled “Image Downloads”.
National Garden Bureau would like to thank our members for providing
the photos for this feature.