Planting, Growing, and Caring for Petunias
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Pretty petunias are popular because of their exceptionally long flowering period. As with most annuals, they get leggy by midsummer, so you’ll want to prune the shoots back by half. See more tips on planting and caring for petunias to keep them blooming.
About Petunias
Petunias are treated as annuals in most areas but can be grown as tender perennials in Zones 9 to 11. The flowers come in many colors and patterns and bloom from spring until frost!
These colorful annuals can really add pop to a front lawn and are often used in borders, containers, hanging baskets, or even as seasonal ground covers. Some even have a slight fragrance. Their height can vary from 6 inches to 18 inches, and they can spread along the ground anywhere from 18 inches to 4 feet.
Types of Petunias
Petunias are divided into different groups, mainly based on flower size:
- Multiflora petunias are the most durable and prolific. They have smaller but more abundant flowers and are ideal for summer bedding or in a mixed border (because they are more tolerant to wet weather).
- Grandiflora petunias have very large flowers and are best grown in containers or hanging baskets (because they are more susceptible to rain damage). These large petunias often do not fare as well in the south because they’re prone to rot during humid, hot summers.
- Floribundas: Floribundas are intermediate between the grandiflora and multiflora groups. Like the multiflora varieties, they are free-flowering and produce medium-sized blooms.
- Millifloras: Milliflora petunias are much smaller than any other petunias on the market. The flowers are only 1 to 1½ inches wide, but they are prolific and last all season!
- Spreading or Trailing Petunias: These are low-growing and can spread as much as 3 to 4 feet. Because the flowers form along the entire length of each stem, they form a beautiful, colorful ground cover. They can be used in window boxes or hanging baskets.
Planting
Petunias need full sun, or they will become spindly. They don’t tend to flower well in shade.
The soil should drain well and not stay overly wet, especially in containers. It should also be moderately fertile to promote the best growth. Amend poor soil with finished compost prior to planting.
When to Plant Petunias
- It’s easiest to buy young plants from a nursery that sells petunias in flats. Look for plants that are short and compact. Leggy petunias with tons of flowers already won’t settle in as fast.
- If you want to grow petunias from seed, start the seeds indoors 8 to 10 weeks before your last spring frost date. (See your local frost dates.)
- Plant young petunias outdoors after your last spring frost date, but keep a close eye on the weather forecast and protect young plants from late frosts.
How to Plant Petunias
- Petunia seeds are very small (dust-like!) and need lots of light in order to germinate.
- When the young plants have three leaves, plant them outside.
- Space the plants about 1 foot apart.
- If you’re planting petunias in containers, use a container potting mix that will drain well.
Types
Multifloras
- ‘Carpet Series’ is very popular. They are compact, early blooming with 1½- to 2-inch blooms that come in a wide variety of colors, and are ideal for ground cover.
- ‘Primetime’ series stay compact and uniform, covered with 2¼-inch flowers.
- ‘Heavenly Lavender’ is an early, compact, double, deep lavender blue with 3-inch blooms on 12- to 14-inch plants.
Grandifloras
- ‘Sugar Daddy’ (Petunia Daddy Series), which sports purple flowers with dark veins.
- ‘Rose Star’ (Petunia Ultra Series), whose flowers look striped because of its rose-pink flowers with a white center.
Floribundas
- ‘Celebrity’ series petunias are compact and rain-tolerant. The flowers reach 2½ to 3 inches across.
- ‘Madness’ series petunias have big, 3-inch flowers in many veined and solid colors. They are compact and bloom until frost. They bounce back well after rain.
- ‘Double Madness’ petunias are compact and floriferous with big, 3-inch flowers all through the summer. Like their single counterparts, ‘Double Madness’ petunias bounce back within hours of a rainstorm.
Millifloras
- ‘Fantasy’ forms neat, compact mounds.
Trailing Petunias
- ‘Purple Wave’ was the first cultivar in the class of spreading petunias. It produces large blooms of deep rose-purple. It is tolerant of summer heat, drought, and rain damage. ‘Purple Wave’ remains under 4 inches tall.
- ‘Wave’ series petunias are available in a multitude of colors. Most are not quite as ground-hugging as the original. They are weather tolerant, disease resistant, and heavy-blooming.
Catherine Boeckmann
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Hi Don,
A simple stake-and-tie support system will work for your petunias. Use traditional bamboo, simple wooden, or metal stakes.
I planted both yellow and pink petunias separately into one pot this May. I just noticed the pink ones were overtaking the yellow in the pot and began pushing the pink over a bit. I then noticed that ONE branch now has both pink AND yellow petunias ready to bloom! Amazing to me! Is this common?
I was given a pot of dark purple petunias for my first Mother's Day and I realized I was watering it a little too often so I've pitched off the squishy wilted flowers. Now I have these long vines with 3-4 flowers on each. It's long and stringy looking plant instead of bunched flowers. Is there a way to make the flowers more of bunches? Would it do better in a hanging pot instead of a sitting pot? Help! I really want to keep this beautiful and healthy!
If you remove the dead flowers, it will prevent those spent flowers from developing seeds. This helps the plant to focus its energy on producing more flowers (instead of seeds). When deadheading, make the cut about ¼ inch below the base of the flower (along the stem), or you can pinch it back to just above the nearest leaf junction. Do not remove just the petals – the entire flower structure, including the base connected to the stem (usually a little swollen area, with several tiny straplike “leaves” surrounding it, called the calyx) needs to be removed.
If the plants are young pinch back some of the growth tips, it will make the plant grow fuller instead of getting leggy. They usually start getting leggy is you don’t deadhead (cut spent flowers off). If the leggy-ness is more extreme, you can always clip all the stems down to 6 inches down, and fertilize the plant. In about a week, they’ll recover and bloom.
The plant willnot necessarily “do” better in a hanging pot; if all conditions are right (see above for planting and care advice) it will do well in a hanger or tabletop.
We hope this helps!
I live in the foothills of the Himalayas in India at altitude 7000 feet. Climate is quiet cool and sometimes we have snow in winter. I want to plant hanging baskets of trailing petunias from seed. I have ordered the seeds from Swallowtail Garden Seeds, United States which should reach me in end July. I want advice about when and how to plant the seeds.
I live in Dorset, UK. I've just put five petunias - two upright and three trailing - into each of three small tubs (13.5 " long x 5" x 5") that are fixed just below the upstairs bedroom window sills, facing due East, so they get the morning sun.
There's a layer of pea shingle at the bottom, covered with a piece of carpet, and the small drainage holes are just below the carpet. I've also added some "water-retaining crystals" to the soil.
I had reckoned to provide each tub with a cup full of water twice a week.
Is this too much or too little ?
Yes, I know - it depends on the weather ;-)
But what do you think ?
I live in Dorset too, and I reckon that's far too little, especially only twice a week. I water every day for young plants and every other day for mature plants if there's been no rain, and water until it starts dripping out the bottom of the container. I think a box that size will need a couple of litres of water at least.
I received my petunia plant for Mother's Day and it was thick with blossoms. I have been diligent with my deadheading the plant by taking the dead flower just below the plant cup that the blossom grows out of. However, instead of a nice full plant I am getting these long branches with one blossom on the end of the plant. Help!
To prevent this, cut back 1/3 of the stems every 10 days. This should promote flowering on all the stems.
Does it hurt to have petunias in full sun?
