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The petunia, which belongs to the nightshade family, originally comes from South America and can therefore deal with direct sunlight much better than with wet and cold weather. If you take good care of your petunias on the balcony or in the garden, you will reward them with a large number of colorful flower heads.

Petunias need a lot of water

How often should petunias be watered?

Since the hanging petunias in particular can take on impressive dimensions, there is a high water requirement in a sunny location due to evaporation. Therefore, you should water your petunias in the window box every morning or evening during the flowering period. But make sure you have a permeable substrate and drainage holes, as petunias do not like waterlogging.

When and how to repot petunias?

After the ice saints, young plants can be planted outside at any time or placed in the window box. Make sure, however, that the roots of the petunias do not lie in direct sunlight and dry out during repotting. If you want to replace withered specimens, replacing the soil in the planter can sometimes be a good idea. Watch for signs of root rot in ailing petunias, as this will be passed on through the potting soil.

When and how to prune petunias

To prevent diseases, it is advisable to collect wilted flowers every few days. Most gardeners don't cut back petunias because they only cultivate them as annual balcony plants. If you want to try overwintering, you should shorten the individual shoots to about 15 to 20 centimeters in length.

What diseases affect the petunia?

The petunia is relatively often attacked by the following diseases:

  • powdery mildew
  • chlorosis
  • root crown rot

What should be considered for optimal fertilization of petunias?

You can encourage growth and flowering by fertilizing your petunias with a liquid fertilizer (preferably low in iron and phosphorus) once or twice a week. During the winter, however, you should not fertilize at all, since new shoots do not get enough sunlight in winter and can show signs of deficiency.

Can petunias be overwintered?

Under the right conditions, the petunias, which are generally very sensitive to frost, can also be overwintered. However, for this you should:

  • select a sufficiently bright location with an even temperature of around 5 to 10 degrees Celsius
  • water very sparingly
  • shorten the shoots to about 15 to 20 centimeters in length
  • do not fertilize during the winter period


If you don't want to do without the moisture-sensitive petunias on the terrace either, you can also plant the similar-looking magic bells. These are less affected by frequent rain and come in the same variety of colors as petunias.

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