While petunias are often found in the wild in their native South America, these nightshade plants cannot grow wild in the open in this country due to their sensitivity to frost. Since petunias can be easily grown from seeds and are inexpensive to purchase, they are often only cultivated as annuals despite the basic possibility of overwintering.
How should petunias be planted for optimal growth?
Petunias prefer a sunny location, well-drained, nutrient-rich substrate and regular watering. They can be grown on the windowsill from January and planted outdoors after the Ice Saints. The flowering period extends from June to the first frost.
What are the main characteristics of these plants?
Petunias grow as herbs and usually have a sticky lining of plant hairs on their shoots, which are called trichomes. With appropriate fertilization and care, some varieties can develop into a hanging carpet of flowers up to one meter long in the balcony box. Since the individual flowers of the petunia constantly wither and are formed again during the flowering period, the sticky flower remains should be plucked off regularly for reasons of appearance and to prevent disease.
Which location do petunias prefer?
Petunias can be planted in partial shade if necessary, but they only develop their full blooms in full sun. Since petunias do not tolerate waterlogging, they should be planted in a substrate that is as permeable as possible and has a high nutrient content. However, a very sunny location in summer also requires almost daily watering.
When can petunias be sown and planted out?
The petunia seeds can be grown in a bright and warm place on the windowsill from January. Since germination is favored by high humidity, you should, if possible, use an indoor greenhouse (€24.00 on Amazon) or use plastic film to cover the cultivation pots. After a few weeks, the young plants can be carefully separated into individual cultivation pots. However, they are only allowed outside after the last night frosts and the ice saints, as petunias are very sensitive to frost.
How to propagate petunias?
Petunias can be grown from purchased or self-collected seeds. If you want to harvest seeds from your petunias yourself for next season, do not remove wilted flowers before the seed pods are ripe. In the summer, you can simply cut off a side shoot about 20 centimeters long from the petunia and, after removing all the flowers and some of the leaves, place it in a glass of lime-free water. As soon as roots have formed about two to three weeks later, this cutting can be planted in the ground.
How long does the flowering period of petunias last?
Petunias bloom from approximately June until the first frost, depending on when they were grown and where they are located. If you want to start the new season as vigorously as possible with overwintered specimens, you must regularly remove flower buds that appear in the winter quarters.
What plant substrate do petunias need?
Petunias usually thrive in ordinary potting soil, but the following factors are important:
- loose, crumbly substrate (easy to root through)
- as permeable as possible (petunias do not tolerate waterlogging)
- very rich in nutrients
Special petunia soil is usually already mixed with a long-term fertilizer to cover the high nutrient requirements. Commercial potting soil can also be watered with an iron fertilizer to prevent chlorosis.
Tip
Since petunias suffer from periods of summer rain and are then only able to display their flowers insufficiently, they should be positioned under a roof overhang if possible. However, if you have covered petunias, you should pay even more attention to sufficient and regular watering.