Night Sky is the first petunia to resemble a trumpet-shaped galaxy full of bright stars. It has won numerous awards in plant and gardening competitions, and for good reason. If you want the best results, temperature is the most important factor to consider when growing Night Sky petunias. Warm days and warm nights make the flowers predominantly purple, or, in extreme cases, completely purple, while cooler days and nights bring out the whiteness in the petals. So, in order to strike a balance between the two, warm days and cool nights are the perfect combination.