How to grow petunias and best varieties

Nothing beats petunias for bringing stunning summer colour to pots and baskets. There has been lots of breeding, producing ever-more colourful varieties, many of which don’t need deadheading, and are resistant to the wind and rain.

Some are trailing, making them ideal for baskets, and others have a more upright habit. There is a bewildering choice of colours and patterns to choose from, so we’ve found the best varieties to add a bright splash of colour to your patio.

Which? Gardening magazine grew a range of popular varieties to see which would give us the best display throughout the summer.

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Key facts

PLANT TYPE Tender perennial, usually grown as an annual

POSITION Full or part sun

SOIL Well-drained and fertile

How to grow petunias: month by month

Best petunia varieties

‘Amore Fiesta’

Height x spread: 50 x 70cm

Where to buy: Thompson & Morgan

The Amore series have banded petals that form heart shapes. ‘Amore Fiesta’ has black cherry hearts surrounded by a creamy-yellow band, making it one of the most boldly coloured of those we grew. It was a prodigious flowerer; the first blooms opening in mid-May and appearing continuously until we ended the trial in October. It didn’t need deadheading. It formed slightly trailing mounds of blooms, making a striking display ideal for pots and baskets. 

Peak flowering: July-August

'Chameletunia Mango’

Height x spread: 30 x 55cm

Where to buy: J Parker's

There are several Chameletunia varieties in different colours. We tried ‘Mango’, which gives subtle peachy-orange and yellow flowers in a mix that changes with the temperature. It was the last to arrive for our trial, so didn’t really get started until mid-June, but it swiftly formed an almost perfect ball of colour in our hanging basket and filled the pot to overflowing. The shifting colours gave season-long interest and it kept flowering well into October, despite the rain at the end of the summer. 

Peak flowering: August-September

‘Night Sky’

Height x spread: 50 x 80cm

Where to buy: Thompson & Morgan; Brookside

While perhaps not to everyone’s taste, there’s no denying that ‘Night Sky’ is an absolutely superb petunia. The deep purple petals are splashed with white, in ever-changing proportions and patterns; making a stunning display that is bound to attract comment. Whether it was gently trailing from pots or cascading over baskets, it looked great. It also held a good shape right through the summer when other varieties had become leggy and it didn’t need any deadheading. 

Peak flowering: July-August

‘Amore Queen of Hearts’

Height x spread: 60 x 95cm

Where to buy: Brookside; Thompson & Morgan

The combination of bright pink love hearts surrounded by a creamy-yellow star makes ‘Queen of Hearts’ arguably the best of the Amore series. The outline of the hearts is crisp and there was no change in the strong colours over the season, so it gave us a constant display that stood out from more subtle colour combinations. The plants filled out quickly and trailed slightly so that it looked good in both pots and baskets. It kept flowering well into October. 

Peak flowering: July-August

Which? members can log in now to see the full results and which are our Best Buy varieties. If you’re not a member, join Which? to get instant access.

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Height x spread: 50 x 70cm

This series have banded petals that form heart shapes. This variety has black cherry hearts surrounded by a creamy-yellow band, making it one of the most boldly coloured of those we grew. It was a prodigious flowerer; the first blooms opening in mid-May and appearing continuously until we ended the trial in October. It didn’t need deadheading. It formed slightly trailing mounds of blooms, making a striking display ideal for pots and baskets. 

Peak flowering: July-August

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Height x spread: 30 x 55cm

There are several varieties of this flower in different colours. This one gives subtle peachy-orange and yellow flowers in a mix that changes with the temperature. It was the last to arrive for our trial, so didn’t really get started until mid-June, but it swiftly formed an almost perfect ball of colour in our hanging basket and filled the pot to overflowing. The shifting colours gave season-long interest and it kept flowering well into October, despite the rain at the end of the summer. 

Peak flowering: August-September

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Height x spread: 50 x 80cm

While perhaps not to everyone’s taste, there’s no denying that this variety is an absolutely superb petunia. The deep purple petals are splashed with white, in ever-changing proportions and patterns; making a stunning display that is bound to attract comment. Whether it was gently trailing from pots or cascading over baskets, it looked great. It also held a good shape right through the summer when other varieties had become leggy and it didn’t need any deadheading. 

Peak flowering: July-August

???

Height x spread: 60 x 95cm

The combination of bright pink love hearts surrounded by a creamy-yellow star makes this variety arguably the best of the Amore series. The outline of the hearts is crisp and there was no change in the strong colours over the season, so it gave us a constant display that stood out from more subtle colour combinations. The plants filled out quickly and trailed slightly so that it looked good in both pots and baskets. It kept flowering well into October. 

Peak flowering: July-August

Full testing results for petunias

USING THE TABLE The more stars the better. OVERALL RATING Ignores price and is based on: flowering duration 30%; flower impact 20%; flower coverage 20%; shape of the plant 15%; resistance to wind and rain 15%. No varieties suffered from any pests or diseases in this trial.

Full testing results for petunias

USING THE TABLE The more stars the better. OVERALL RATING Ignores price and is based on: flowering duration 30%; flower impact 20%; flower coverage 20%; shape of the plant 15%; resistance to wind and rain 15%. No varieties suffered from any pests or diseases in this trial.

Caring for your plants

Planting

When your petunias plugs arrive you can plant them straight into pots or baskets, mixing in some controlled-release fertiliser with a Best Buy compost for containers.

These can be grown in a light, frost-free place until you’re ready to move them outdoors when the danger of frost has passed. They do best in a bright, sunny spot but will tolerate light shade.

Watering 

Petunias are drought-tolerant, but keep them well-watered as they will dry out quickly in pots and baskets.

How to deadhead petunias

To keep your plants looking tidy and to help encourage them to produce more blooms you can remove the faded flowers to the base of their stems. It's a sticky job though and many modern petunia varieties are 'self cleaning' so it's not vital that you deadhead petunias.

Feeding

Controlled-release feed usually runs out towards the end of summer, so when this happens start giving a liquid feed once a week to keep the display going for longer. 

Common questions

Are petunias perennials?

Petunias are tender perennials so are best thrown away at the end of the summer as they won't survive the UK winter outdoors. Start new plants each spring. Some varieties are available as seed and can be sown indoors early in the year, while others are only available as plug plants from nurseries or garden centres.

Are petunias poisonous to cats or dogs?

Fortunately petunias are not toxic to cats or dogs so you can have them safely in your garden if you have pets.

Do bees like petunias?

We've never found that bees or other pollinators are particularly attracted to petunias in our trials for Which? Gardening magazine. If you'd like to help these insects with your patio display, try our best patio plants for pollinators.

Common growing problems

Greenfly

Squash any aphids before they can develop into larger infestations that may cause damage

Read more about greenfly.

Slugs and snails

Slugs and snails can nibble holes in your plants. Scatter organic slug pellets sparingly around the plants or remove any slugs and snails you see.

Read more about slugs and snails.

Powdery mildew

Petunias can be prone to the white coating of mildew, so make sure you keep them well-watered to avoid stressing the plant.

Read more about powdery mildew.

How we test petunias

We chose 17 varieties of single petunias including examples of new breeding and old favourites.

We planted three plugs of each variety in a nine-litre pot and also into a 30cm basket with our Best Buy compost for containers mixed with Best Buy controlled-release fertiliser.

We put them outside once all danger of frost had passed and kept them watered with an auto-irrigation system.

We monitored them throughout the summer to see how good a display each variety gave and how long they flowered for. If any plants looked a bit pale or stopped flowering, we topped them up with a liquid feed in August.

We ended the trial in October.