There are many colorful variants of petunias, which makes the easy-care summer flower a popular plant for balconies and gardens. The lush flowers can be admired during the entire vegetation period from spring until well into autumn. So that you can enjoy them undisturbed, we have put together the most important facts about planting and caring for petunias for you.

The garden petunia is a popular balcony and garden plant

Table of Contents

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  1. origin and distribution
  2. use
  3. appearance and growth
  4. leaves
  5. flowers and flowering time
  6. toxicity
  7. Which location is suitable?
  8. substrate / soil
  9. Prefer
  10. Plant petunias properly
  11. What is the best planting time?
  12. The right planting distance
  13. Water petunias
  14. Fertilize petunias properly
  15. Pruning petunias properly
  16. Propagating petunias
  17. hibernate
  18. diseases and pests
  19. species and varieties
  20. origin and distribution

    Strictly speaking, the garden petunia that is so popular with us is not a species of its own, but a hybrid of the purple petunia (Petunia integrifolia) and the white petunia (Petunia axillaris) that was bred back in the 19th century. It is characterized by a large variety of flower colors and growth forms, is easy to care for and extremely floriferous.

    The original wild forms come from the climatically moderate to subtropical regions of South America and are particularly widespread in Brazil, Bolivia, Paraguay, Argentina and Uruguay. It is also not a single species, but a separate genus of plants with around 16 different species. Petunias (bot. Petunia) belong to the nightshade family (Solanaceae) and are closely related to the tobacco plant (Nicotiana). The name of the plant also refers to this: “Petun” means nothing other than “tobacco” in one of the languages of the native people of Brazil, Guarani.

    The petunias available on the market are usually garden petunias; special types and their varieties are rarely offered.

    use

    Because of their climbing, dense growth and the lush abundance of flowers, petunias are popular perennial plants for flower boxes (€16.99) or hanging baskets as well as for pots. Here, the colorful flowering wonders are suitable for dense planting - either solo or in combination with other species - as well as for solitary use. Furthermore, petunias can be used excellently as underplanting for tall stems or other trees, for example as a supplement to hybrid tea roses or lantana.

    But not only on the balcony, also in the garden bed, petunias cut a fine figure. Especially with other annual, fast-growing summer flowers such as

    • tagetes
    • verbs
    • pelargonium
    • lobelia
    • snowflake flowers
    • fuchsias
    • or coneflower

    the flowers enter into a suitable alliance. If you don't want to distract from the bloom with other flowering plants, you can combine petunias with ornamental leaf plants such as stinging nettles or ground ivy. Herbs, especially Mediterranean ones such as sage, thyme, oregano, etc., and vegetables can also be very well socialized with the uncomplicated petunia.

    Incidentally, blooming petunias on the balcony or terrace also fulfill a very practical purpose: the plant is supposed to drive away annoying mosquitoes that don't like the scent of the flowers at all. This works particularly well if you plant the flowers together with other plants that mosquitoes do not like. Lavender, rosemary, basil, for example, but also lemon balm, marigolds and tomatoes are suitable for this.

    appearance and growth

    Strictly speaking, the petunia is not a flower, but a fast-growing and shrubby herb. The garden petunias, which are usually grown once a year, can reach a height of between 20 and 70 centimeters, depending on the variety. The gardener distinguishes between upright and trailing petunias. These varieties, also known as cascading petunias, develop long shoots covered with numerous flowers and are therefore particularly suitable for planting in hanging baskets or balcony boxes.(109.00€)

    Incidentally, the magic bells (Calibrachoe), which look very similar to a petunia, are not small-flowered varieties, but a separate plant genus. However, both the magic bells and the petunias belong to the nightshade family (Solanaceae) and are therefore closely related.

    leaves

    The petunia's dark green, entire, and slightly hairy leaves contrast starkly with the bold, fresh colors of the trumpet-shaped flowers. The plant hairs, also known as trichomes, are often sticky. Typically, the stalked leaves of the petunia are arranged alternately, although there are also species and cultivars with leaves arranged in pairs.

    flowers and flowering time

    Garden petunias are traditionally divided into four different groups according to the size and abundance of their flowers:

    • Grandiflora petunias: very large, flat and trumpet-shaped flowers, solitary on the stem, sensitive to rain
    • Multiflora petunias: compact habit, numerous short-stalked flowers with a diameter of up to five centimetres, not sensitive to rain
    • Floribunda petunias: numerous flowers up to about eight centimeters in size, sensitive to rain
    • Milliflora petunias: numerous tiny flowers, only between two and three centimeters in size

    The so-called "rose petunias", on the other hand, are varieties whose full, round flowers are reminiscent of rose petals.

    Typical of all petunias are the trumpet-shaped, delicate flowers in numerous summery colors. In addition to monochromatic varieties in white, pink, red, violet and blue, there are also fascinating variants with spotted, stared or striped flowers. With all varieties, the lush splendor can be tirelessly admired between May and October with appropriate care.

    toxicity

    As with almost all nightshades, the green parts of the petunia contain solanine and are therefore poisonous. The leaves in particular must not be nibbled on or eaten by humans or pets. However, petunias contain less of the toxic solanine than potato plants, for example, and the hairy, scratchy leaves do not taste particularly good.

    When consumed, u. a. typical symptoms of poisoning such as nausea, diarrhea and vomiting. However, these signs are not produced by a mere touch. However, the sticky plant hairs can trigger allergies in sensitive people, which manifest themselves in symptoms such as itching, reddened and/or irritated skin. For asthmatics, however, the flowers are harmless.

    Which location is suitable?

    Petunias bloom more beautifully the sunnier they are. A warm, wind and rain-protected location is therefore best suited for the summer-blooming flowers, regardless of whether they are on the balcony or in the garden bed. Heat and blazing sun do not damage the lush bushes with the delicate flowers, but they are sensitive to wind, cold and rain - and the larger the flowers, the more so. The Grandiflora varieties in particular belong in a place that is protected from rain, as the colors of the large flowers quickly fade when wet. Small-flowered varieties, on the other hand, are much more robust against the effects of the weather.

    If you cannot offer your petunias a location in full sun, plant them in the light semi-shade. The plants also thrive very well there, but do not produce as many flowers.

    substrate / soil

    For keeping them in buckets, we recommend using special petunia soil, which is available in every hardware and garden store. In most cases, however, commercially available compost-based potting soil is perfectly adequate. However, make sure to choose a high-quality potting soil without peat. Inferior substrates often lead to yellowed or otherwise discolored leaves, as after a while there is an iron deficiency due to unsuitable soil and / or an insufficient supply.

    If, on the other hand, the petunias are to be planted in the garden borders, you should plant them in loose, humus-rich, well-drained soil and, if necessary, enrich it with mature compost or stable manure.

    Prefer

    In the spring, the various petunia varieties are available cheaply in stores. If you enjoy growing your own plants, you can also win your own petunias as bought or collected seeds. Keep in mind, however, that hybrid strains in particular may be sterile (i.e. unable to produce viable seed) or they may not reliably pass their traits on to their offspring. This applies in particular to trailing petunias, whose offspring often exhibit upright growth. Propagation via seeds is always a surprise anyway, since different characteristics are always mixed up again.

    You can grow petunias on the windowsill as early as January, although sowing between February and March is still perfectly adequate. The plants are light germs, which is why the seeds should not be covered with potting soil, but should only lie on it. Always keep the substrate slightly moist and place the seed pot in a light but not directly sunny location with a temperature of around 20 °C. At best, cover it with a hood, which can also consist of a cut-off PET bottle or foil.

    The seedlings are pricked out as soon as the second pair of leaves has developed. However, you should wait until mid to late May before planting them out, because petunias are sensitive to frost and can be seriously damaged by late night frosts.

    Plant petunias properly

    Since petunias like to be in warm and sunny locations, they have a correspondingly high water requirement, which, however, must not degenerate into waterlogging. Accordingly, good drainage must be ensured, especially when kept in a bucket, for example by filling in a layer of gravel on the bottom of the pot. This regulates the water balance and also ensures that excess water is quickly drained to the outside. There must be a drainage hole at the bottom of the pot for the irrigation water to drain into a saucer or the planter. Remove it from here immediately after watering so that the plants do not get "wet feet".

    If the heavy, loamy garden soil tends to be wet or permanently damp, drainage in the planting hole is also recommended here. To do this, place a layer of gravel on the bottom of the planting hole and mix the excavation with loose substrates such as compost, sand, etc. In any case, when planting outdoors, you should generously add compost to the planting hole to give the petunias enough nutrients to get started.

    For potted specimens, you should not choose a planter that is too small, so that the roots have plenty of space and the plants can develop well. On the other hand, planting too narrowly not only leads to growth disorders, but also promotes diseases and pest infestation.

    Before planting, place the plant in a bucket of water so that the roots can soak up the moisture. Also water carefully after planting and mulch the root area, for example with bark mulch. This ensures that the moisture in the soil does not immediately evaporate again, and the roots are also kept cool - in contrast to the above-ground parts of the plant, they do not like too much heat.
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    What is the best planting time?

    The frost-sensitive petunias are only allowed outside for good in late spring/early summer, after you have gradually accustomed the young plants to a location in the fresh air. The flowers are severely damaged by sudden night frosts and should therefore be protected from them.

    The right planting distance

    The optimal distance between two plants is about 15 centimeters.

    Water petunias

    Even if petunias are considered easy to care for, they are anything but undemanding. They must be supplied with water regularly, especially during the hot summer months, whereby the substrate must not dry out if possible. If this happens occasionally, short-term drought is not a problem, but in the long term it will lead to the death of the plant. Petunias, especially those grown in pots, should be watered two to three times a day on hot, dry days.

    The pretty flowering plants do not tolerate drought, but they do not like waterlogging either. Therefore, only water when necessary, which you determine based on the degree of dryness of the substrate: it is time for a strong watering from the watering can again when the potting soil has dried on the surface. Use low-calcium, soft water for watering, such as well-stale tap water or collected rainwater. Hard water, on the other hand, can become problematic because it disrupts the supply of nutrients. However, if you live in a region with calcareous water, you can counteract discolored leaves and the resulting diseases due to a lack of nutrients by filtering the tap water and also administering a good iron fertilizer.

    Never wet the leaves or flowers of the petunia when watering, as this can cause burns (drops of water act like magnifying glasses in the sun) or promote fungal diseases.
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    Fertilize petunias properly

    The petunia needs a lot of nutrients for its lush flowers and must therefore be fertilized regularly. If the flowers are to be in the garden bed, put a long-term fertilizer suitable for flowering plants in the planting hole. The compost that is also added will not meet the high nutrient requirements. Potted plants, on the other hand, provide you with a phosphorus-rich, liquid universal or flowering plant fertilizer (€10.47), which you administer with the irrigation water every two weeks or according to the manufacturer's instructions. Phosphorus is essential for plants and promotes flowering, while nitrogen primarily stimulates shoot growth. If the petunia develops yellow leaves, it is suffering from an iron deficiency and should be supplied with a special iron fertilizer.

    Pruning petunias properly

    A strong pruning is only necessary if you want to overwinter the petunias. In this case, use the scissors before putting them into the winter quarters and repeat this measure before clearing them out in spring. At this point, you should remove thin and weak shoots that have grown over the winter.

    Otherwise, you only pluck off faded flowers during the flowering period so that the plant keeps developing new inflorescences. In addition, faded shoots quickly become unsightly and sticky, which is why cutting them off also has visual reasons. If you don't clean them out, petunias will develop seed heads, which you can collect shortly before they ripen and keep them dry and dark over the winter. To avoid the faded inflorescences from sticking together, carefully pluck off just the petals. After that, a small, green ovary remains, from which the seed capsule finally develops. Between January and March, use the seeds inside to grow your own petunias.

    Propagating petunias

    In contrast to growing from seeds, petunias can be propagated by cuttings. Since this form of propagation is basically a clone of the mother plant, they have the same characteristics and you are sure to be surprised. The easiest way to propagate cuttings is as follows:

    • In early summer, cut off a side shoot about 15 to 20 centimeters long.
    • Remove all flowers from this.
    • Pluck off the leaves except for the pairs of leaves on the top five centimeters of the shoot.
    • Place the cutting in a glass of soft water.
    • Place the jar in a bright location that is not directly sunny.
    • Change the water every two days.

    After about two to three weeks, the cutting will form its first roots, so that you can plant it in suitable soil and cultivate it like any adult plant.
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    hibernate

    Since petunias are not frost hardy and are available every year in great variety and for little money, they are usually only cultivated once a year.In fact, however, they are perennial plants that you can overwinter with a little effort and plant out again next spring. You have several options for this:

    • Seeds: They only collect the seed pods together with the seeds and overwinter them in order to use them in February to grow new plants. Last year's petunias, on the other hand, are put on the compost in autumn.
    • Plants: Overwintering adult plants, on the other hand, is a bit more complex. The best way to do this is as follows:
    • Place petunias in their winter quarters before the first frost.
    • Cut the plant back to about 20 centimeters.
    • A bright, frost-free room with a temperature of between five and ten degrees is ideal.
    • Protect petunias from heating air.
    • Don't fertilize, just water a little occasionally.

    In the spring, gradually get the petunias used to the sun and warmth again, but don't put the plants outside too early. From April you also start with the appropriate fertilization and gradually increase the watering frequency.
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    diseases and pests

    Petunias are quite hardy plants, but they can be attacked by diseases and/or pests due to poor care. The following occur particularly frequently:

    • Powdery mildew: occurs mainly in hot, warm weather, cut out affected parts of the plant generously and spray the affected plant several times with a mixture other than whole milk and water
    • Root rot: caused by constant moisture in the substrate / waterlogging, immediately repot affected plants in fresh substrate and generously cut away rotten roots and diseased shoots
    • Whitefly: occurs in heat and high humidity, hang yellow boards and spray plant with soft soap solution (a few drops of dish soap and vegetable oil on some water).
    • Aphids: Spray the infested plant with a soft soap solution or fresh nettle broth

    Not only in summer, but especially in winter, you have to watch out for pest infestation and possible signs of illness. Check the overwintering plants regularly and react as quickly as possible.

    tips

    If you are looking for particularly hardy and less susceptible varieties, you should choose petunias with single, small purple or blue flower colors. These usually tolerate wind and rain quite well, whereas white-flowered varieties are often quite susceptible to chlorosis.

    species and varieties

    Petunias have been cultivated intensively since the middle of the 19th century. Nobody can say exactly how many varieties there are these days. Newer breeds often come up with pretty colors and are considered to be particularly robust, for example the Surfinia line from Japan. We will briefly present some of the most beautiful variants for pots and gardens here:

    • 'Big Time Blue': simple flowers in a beautiful blue, very robust
    • 'Cascade Orchid Mist': trailing petunia with double double flowers, bicolor white and pink
    • 'Celebration Blue': strong blue flower color, also thrives in semi-shade
    • 'Celebration Sky Blue': trailing petunia with beautiful blue flowers
    • 'Johnny Flame': flowers with a star pattern, dark violet with a lighter edge
    • 'Lavender Shades': beautiful blue-purple flower colour
    • 'Pearly Wave': vigorous trailing petunia, two-tone white and pink flowers
    • 'Purple Pirouette': double double flowers, purple with a white edge
    • 'Red Pirouette': double double flowers, red with a white edge
    • 'Rosy Ripple: double flowers with a white and pink pattern

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