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Home & garden.

14 July 2021

How to grow petunias

Petunias are great for summer hanging baskets and patio pots. Learn how to grow them and try our Best Buy varieties
CT
Ceri Thomas
Petunias

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.

How to grow petunias: month by month

January
February
March
April
May
June


POT UP INDOORS
POT UP INDOORS
MOVE OUTDOORS

July
August
September
October
November
December
FLOWERING
FLOWERING
FLOWERING
PULL UP


Best petunia varieties

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.

Best Buy petunias
What it looks like
Variety name
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
What it looks like
Variety name
Height x spread
30 x 55cm
This variety 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
What it looks like
Variety name
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
What it looks like
Variety name
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

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.

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.

Deadheading

Remove the faded flowers to the base of their stems to prolong the flowering season. 

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 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.