Galaxy Petunia Plant Profile

A True Showstopper That Will Look Great in Hanging Baskets and Containers

Galaxy petunias

The Spruce / Kara Riley

If you're looking for a showstopping flower that'll look spectacular in containers, cascading over the sides of hanging baskets, or being used as an eye-catching bedding plant, look no further than the galaxy petunia.

Also called night sky petunia, this new species was created by an Italian plant breeder who crossed two other petunia varieties. It's no surprise the plant won the prestigious Fleurostar award for 'Winner with the Wow Factor' when it was released commercially in 2016.

The purple trumpet-shaped flowers have white spots dotted across them that create an other-worldly look reminiscent of the cosmos. It's a shame that these annual plants only last one growing season, but once they're in bloom the flowers remain until the late fall when the first frosts hit.

It's worth noting that the temperatures of their environment heavily influence the blooming pattern of galaxy petunias. If the weather is too hot, the plants might not display the white spots giving them their impressive appearance. You may have to wait for the cooler nights, closer to the end of the summer, before they start to resemble a starry cosmos again.

Botanical Name Petunia 'Night Sky'
Common Name Galaxy Petunia, Starry Sky Petunia
Plant Type Perennial herbaceous species
Mature Size Up to 14 inches
Sun Exposure Full sun
Soil Type Not particular
Soil pH Not particular
Bloom Time Summer through fall
Flower Color Purple with white specks
Hardiness Zones 9 to 11
Native Area Developed in Italy
purple galaxy petunias
The Spruce / Kara Riley 
side view of galaxy petunia
The Spruce / Kara Riley 
frontal view of galaxy petunia
The Spruce / Kara Riley 
new galaxy petunia growth
The Spruce / Kara Riley 
front view of a galaxy petunia
The Spruce / Kara Riley 

How to Grow Galaxy Petunia

While petunias are only annual flowers that normally just have one full growing season, they're fast-growing and have a long bloom period.

It can be tricky to get the white spots to flourish on these plants, but even when they're just solid purple, they'll make a nice addition to your garden.

If they have a sunny position, they won't require much maintenance. It's also a bonus that they aren't phased by urban pollution, making them a great choice for city gardeners.


Although this plant is easy to grow, it does need a full sun position. If they have too much shade, galaxy petunias won't produce so many flowers, and they won't be as healthy, often suffering from stem stretch.


Your galaxy petunia isn't a fussy plant when it comes to soil types. The main requirement is that you select one with good drainage. It won't tolerate standing water and prefers even moisture.

Ideally, you want a soil that is also rich in organic matter. Their long blooming season means galaxy petunias use a lot of energy and fertile soil will supply them with the nutrients they need to flourish.


Although they don't like to be dry for long periods, overwatering is a problem for the galaxy petunia. Stems can weaken, and flowers won't be so healthy if they get wet feet from standing water. It can also increase the chances of the plant developing Botrytis (a gray mold fungal disease). Weekly watering in the warm months is usually sufficient.

If your galaxy petunias are growing in hanging baskets or containers, they'll need more frequent watering than those grown in the ground - possibly even daily in the hot summer months. It's generally recommended to water when the top of the soil is dry to the touch .

Temperature and Humidity

Temperatures can have a big impact on the striking pattern that the galaxy petunia is known for. Warmer summer temperatures have been shown to result in less white spots. You'll likely find that the patterns on your flowers will change throughout as the season progresses.

When things are at their hottest during the day, and at night, the flowers may be a solid purple color. As the night temperatures become milder and have a greater contrast to the day temperatures, the white spots should begin to appear again.


Your long-blooming galaxy petunia will benefit from regular fertilization, particularly if the soil they are in isn't particularly rich. If they're kept in hanging baskets or containers, feeding them a balanced, slow-release fertilizer every fortnight should be sufficient.

For those grown in the grown as bedding plants, once every three or four weeks will likely be enough.

Propagating Galaxy Petunia

If you plan to propagate your Galaxy Petunia from cuttings, make sure you use a well-drained medium that is kept moist but not saturated and that the temperatures are not too hot.

After around three to four weeks, pinching is recommended to improve growth, and your rooted plant should be ready for transplanting.

Steer clear of B-Nine if you use a plant growth regulator. This has been shown to turn the flowers white.

Growing From Seeds

Some commercial nurseries do sell galaxy petunia seeds. Always opt for a reputable supplier to be sure you're getting the right hybrid and be prepared for a challenge.

The tiny seeds can take up to twelve weeks for germination, and they need plenty of light and only a light covering of soil.