Petunias come in a full spectrum of colours and shapes, making these unfussy blooms a reliable choice for summer containers. And since these blossoms are easy to cultivate and grow quickly, once their seeds germinate, you can expect to see full-size plants in just 12 weeks.
A petunia’s scent makes these plants even more special, injecting the air with a lovely fragrance—a trait that makes them quite “attractive to pollinators, especially when paired with species such as verbena bonariensis and lantana,” says Eric Groft, CEO, and Director of OvS and author of Beyond Bold.
To grow petunias from seed, get started at least 10 to 12 weeks before your last spring frost and follow these steps, courtesy of Groft.
“[It’s more] common to buy young petunia plants from a nursery,” says Groft, adding, that it is key to “plant them outdoors after the last spring frost—but be mindful of the weather and protect young plants from late-season frosts.”
As for where to plant your mature plants after you bring them home? Be mindful of your garden’s light when choosing a plot. Some varieties require a minimum of six hours of direct sunlight per day—but most varieties thrive without strong sun, especially during the peak of summer when UV rays become too strong.
Petunias only bloom well under the correct watering conditions and will not thrive in soggy soil (which can also cause root rot) or when left too dry for extended periods of time. Typically, giving petunias 1 to 2 inches (0.02 to 0.05 metres) of water (when you don’t have rainfall) is sufficient, but “plants growing in containers with limited soil or direct sunlight will require more water than plants growing in garden beds,” says Groft.
It’s best to feed petunias with a balanced liquid fertiliser as soon as you start planting. Adding a layer of compost for more nutrient-rich soil is also beneficial. For maintenance, use a liquid fertiliser every 2 to 3 weeks to keep your plants thriving. Still, depending on your petunia type, it’s always best to check your individual plant’s care instructions to ensure you apply the correct amount of fertiliser.
To grow a fuller, lusher plant, pinch back your stems. How much you pinch depends on the petunia you are planting. Whatever variety you pick, “most petunias also require and benefit from deadheading, which will encourage more growth and keep your plant looking fresh,” adds Megh Wingenfeld, a home and garden expert.
Always transplant your petunias on a cloudy, cool morning. This will stress the plants less than planting on a hot, sunny day.
Petunias have been around since the 19th century and are one of the most popular flowering plants in every nursery. They fall into six main categories, nearly all of which come in a myriad of patterns and colourways and can be grown as annuals in most zones; petunias might thrive as perennials in more temperate regions, including zones 9 through 11.
As the name indicates, spreading or wave petunia plants can reach up to 4 feet; they bloom profusely, making them an exceptional ground cover option. Fairly drought tolerant, spreading petunias also boast long-lasting blossoms, so long as you nourish them with a water-soluble fertiliser every two weeks (and give them at least six hours of sunlight per day).
A more compact iteration, multiflora petunias work extremely well in windy climates due to their strong stems. But, this variety also tends to produce the tiniest blooms. A few common types of multiflora petunias include, mirage, primetime, and carpet. The best part? Multiflora varieties require virtually no deadheading. Thanks to their “self-cleaning” ability, their flowers fall off automatically when spent.
One iteration especially, dubbed supertunia, is considered the “elite” version of petunias. Larger than wave species, petunias that fall into this camp like to spill or spread out (which makes them winners in containers or baskets!). This hybrid, says Wingenfeld, makes growing and caring for petunias even easier; like multifloras, they do not require deadheading and bloom all season long, she adds.
Although Grandiflora petunias produce fewer blooms than other varieties, each bloom grows quite large, ranging between 3 to 5 inches (0.07 to 0.1 metres) in diameter. These petunias do require deadheading and will not flourish in extreme weather conditions like hard rain, humidity, and high heat.
Another aptly-named iteration, these bright, bold, trailing petunias, which often have crisp white edges, cascade beautifully over baskets, planters, and window boxes—but they work in the ground, too (they’ll provide ample ground cover). They thrive in full sun and require moderately moist soil.
These petunias are defined by their bell-shaped blossoms and are most often used as draping plants—they look lovely tumbling over a railing or basket. They grow up to 20 inches (o.5 metres) tall and prefer full or partial sun and nutrient-rich soil. Expect to see blooms from spring through late fall.
A few common diseases that can overwhelm petunias include stem, crown, and root rot, which all occur due to poor drainage (and over-watering). Botrytis blight can also occur, which may cause discolouration of your petunia leaves and flowers—another condition caused by excess watering. In these cases, it’s best to prune any infected sections and dry your bed out to prevent re-infestation, Groft says.
Powdery mildew is also common, however, this disease can occur sans wet conditions. This type of mildew forms when plants are spaced too tightly together and lack proper airflow. To spot this mildew, look for powdery white-coloured spores spread out on your leaves and flowers. Neem oil can help, but correcting the plant’s spatial conditions is equally as important.
If you notice any sagging petunias, the cause is usually due to insufficient water reaching its roots. Inadequate watering can also cause root binding. If this occurs, cut your plants back by half their height, encouraging new, healthier growth.
This story first appeared on www.marthastewart.com
(Credit for the hero and featured image: Narinnate Mekkajorn / Getty Images)
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