Petunia (lat. Petunia) is a genus of herbaceous perennials and dwarf shrubs of the family Solanaceae, growing in the tropics of Brazil, Argentina, Bolivia, Uruguay and Paraguay. The plant name comes from the Brazilian word "petun" meaning "tobacco", the cousin of which is a petunia. One species occurs even in North America. There are about twenty-five species of petunia that sometimes differ greatly. Petunias have been cultivated since the 18th century. Created by breeders over a century ago hybrids are grown as balcony or garden annuals. Florists are attracted by large bright petunia flowers that adorn the garden or terrace with their rich blooming during all season. In addition, petunia is harmoniously combined with other garden flowers – pelargonium and begonia. A spreading petunia looks very beautiful in the compositions of varieties of different colors. And the main reason for the popularity of this flower is that it is not difficult to plant and grow it.
- 1. Audio article (coming soon)
- 2. Description of petunia flower
- 3. Species and varieties of petunias
- 4. Growing petunias from seed
- 5. Petunia planting
- 6. Care for petunia
- 7. How to collect petunia seeds
- 8. Petunia after flowering
Description of petunia flower
Petunias have a bushy shape. Stems can be prostrate, erect, or branching densely. Plant height can be from 6 to 27 inches, petunia leaves are oval and entire with the length from 2 to 5 inches, arranged alternately, green or dark green in color. The stems and leaves are pubescent. The flowers are funnel-shaped, single, on short peduncles, axillary or terminal, actinomorphic or not quite actinomorphic, simple or double, sometimes fringed. The color of flowers can be reddish, purple, white, pink and blue, with a halo, border, with dark veins or a white star. The fruit is a double capsule with small seeds. Petunia that is grown in the gardens and terraces is a hybrid bred from wild species of violet-flowered petunia and large white petunia. Garden petunia blooms from July till frosts. Perennial petunia is grown only as an annual plant.
Hybrid varieties of petunia are divided into two groups – multiflora petunia and grandiflora petunia.
It starts blooming earlier than grandiflora petunia by forming a large number of flowers up to 2 inches in diameter that bloom for a long time. They are true garden flowers as they are not demanding and they are not afraid of rain, grow in any soil and enjoy the sun. Maybe they are not as elegant as grandiflora petunia but compact bushes that are entirely covered with flowers of different colors until autumn frosts are a true pleasure to the eye of a flower grower. Popular varieties of multiflora petunia are:
- Fantasy is a series of nine hybrids, diameter and plant height are 8 inches, flowers are 1.5 inches in diameter; colors are crimson pink, red with veins and a white throat, violet-blue, salmon, white, crimson red, pale pink with a creamy throat, pale salmon with dark veins, etc.;
- Mirage is a series of 13 compact hybrids with double flowers of 2-4 inches in diameter; colors are pink lilac with purple veins, pink with dark pink veins, pink with red-crimson veins, red with burgundy veins, white, maroon red etc.;
- Plum crystals is a bush of 12 inches in height and 10 inches in diameter, flowers are up to 3 inches. The color of flowers gradually becomes lighter: first, it is mauve, then it becomes light lilac and then it is slightly lilac. The contrast to base color is made by purple-maroon veins.
It is the most popular group of hybrids that numbers hundreds of varieties. As the name implies, it has beautiful large flowers. However, it does not have so many flowers as multiflora petunia has. A major shortcoming of this group is that its flowers are easily damaged by rain and wind that spoil their look. Therefore, this petunia is usually grown in pots or containers indoors, in balconies and terraces. This group is divided into several subgroups: large-flowered (shrub is up to 24 inches in height, flowers are smooth and 3-4 inches in diameter), low large-flowered (10-12 inches in height, other characteristics are the same as that of the large-flowered), large-fringed and low large-fringed ( the shrub height is 25-27 inches and 10-12 inches respectively, fringed flowers are up to 5 inches in diameter), large-excellent and low large-excellent (bush height is 20-30 inches and 12-16 inches respectively, smooth flowers are with a wide throat 4-5 inches in diameter covered with veins that are darker than the background is) and large double flowered (the shrub height is 20-24 inches, large double flowers are with smooth or fringed edges and 4-5 inches in diametre). The most popular series of petunia grandiflora are:
- Hit Parade is early season hybrids up to 10 inches in height with a wide range of colors: pink, crimson, white, with a white star on a blue background, salmon, blue-violet, etc.;
- Picotee is a series consisting of four hybrids. The border of petals is its distinguishing feature: it is heavily corrugated, white, 0.6 inches wide. The height of the bush is 10 inches. The color of flowers is red, purple, pink, blue-violet, crimson;
- Purple pirouette is a violet-purple double-flowered hybrid with a white border on the edge of the corrugated fringed petals. The bush height is 10 inches.
Besides these two most popular groups of petunias, there is also floribunda petunia that occupies an intermediate position between the first two. The flowers of this group practically cannot be damaged by rain the same as the flowers of multiflora petunias, but this plant looks impressive only if it is planted in large quantities. So it is grown mainly in the large flower beds. Its varieties are:
- Sonia is a popular series of 11 hybrids. The height of the bush is 10 inches; flower colors are pink, crimson, raspberry-pink with a white star, purple-maroon with a white star, red with a white border, white, red, light violet with violet veins, etc.;
- Celebrity is a series of heat- and rain-resistant hybrids presented in thirteen colors and they can be one-colored or two-tricolored.
Spreading, or trailing, petunia differs from other groups by its long and flexible stems that tend to grow down. Petunias of this group grow quickly and are resistant to bad weather conditions. Varieties of spreading petunia are:
- Surfinia flower is 2-4 inches in diameter, except for miniature varieties “Pink Mini”, “Mini Purple", the flowers of which are 2 inches in diameter. Of all possible shades, Surfinia petunia does not have only orange and bright yellow colors;
- Tumbelina is a product of Japanese company Suntory. The flowers of this series are doubled.
- Conchita is a series of hybrids, the shape and size of its flower look like the flowers of Calibrachoa (mini petunia). Smaller flowers are 2 inches in diameter, of various colors and patterns.
Petunia from seed: sowing
Novice growers quite often ask how to grow petunia from seeds. If you have the opportunity to arrange additional light for seedlings, then sowing of petunia seeds to grow seedlings can be carried out in February. But usually the seeds are sown in the second half of March, and you need to sow a large amount of seeds since due to insufficient length of daylight seed germination is very low. The soil for planting should be loose, light and nourishing: two parts of leaf or sod soil, two parts of rotted humus, one part of sand, and two parts of peat. The upper soil layer of about 0.4 inch deep needs to be sifted for the seeds to be sown on its surface evenly. The soil needs to be well watered a day before sowing. The seeds are mixed with a dry sand and sprinkled on the top of soil, leveled, sprayed, covered with glass or foil and kept at the temperature of 68-73ºF to germinate. In a week the seedlings appear that will require spraying twice a day and airing. The main task during this period is to ensure high air humidity in the greenhouse while avoiding the risk of root rot disease caused by moisture. Therefore daily as soon as condensate appears on the glass or foil, the glass should be turned up and the foil should be wiped out. In addition, from time to time, the seedlings need to be sprayed not by water, but by a light solution of potassium permanganate. When the first leaf of seedling appears, the glass can be removed, the soil should be lightly sprinkled with sand, and watering should be reduced.
When shoots get 3-4 true leaves, they are pricked out. The soil in the container should be pre-moistened. A seedling is carefully hooked with a small stick and removed from the soil by taking hold of the leaf and trying not to shake off the soil from the roots. Then a seedling is pricked out into a peat or plastic pot with the same soil mixture. Transplanted plants are watered and covered by a paper or some other protection fabric for two or three days. At this stage of growth petunia requires an attentive care, and the most important point is to keep the soil in a state of constant moderate humidity. Frequency of watering during this stage depends on many factors, so you should decide by yourself whether you will moisten the soil 2-3 times a day or just 1-2 times a week. Do not forget to loosen the soil around the seedlings. Fertilizers are applied weekly in a week after pricking out the seedlings alternating between leaf and root feedings. For this purpose you can use nitrophosphate and other combined water-soluble fertilizers at the rate of approximately 0.88-1.2 oz per 1.75 pints of water. The varieties of multiflora petunia bloom in two and a half months after being planted, the varieties of grandiflora petunia bloom in three months. Before planting in open ground it is desirable to hold the already grown seedlings in a cool place or expose them to fresh air for some time during a day for acclimatization.
When to plant petunia
Petunia prefers to grow in sandy or loamy fertile soils. It reacts well on compost or humus, but not on manure that contributes to the development of fungal diseases. The site should be open and sunny. Planting out of petunia seedlings is carried out when all the spring frosts have gone (approximately in the second half of May), and it is better to do this in a cloudy day or in the evening.
How to plant petunia
If you plant an already flowering petunia, it will bloom until November. Usually petunia is planted on the edge of the flower beds because of its small height. Seedlings are preliminary well watered in pots and then planted with a clod of soil keeping the distance of 12-16 inches between the bushes. After being planted, petunia is watered and the next day the site is mulched.
How to care for petunia
Growing of petunias does not require superhuman efforts, but for the best results, you should have a strong theoretical knowledge on how to care for petunia. Despite the fact that the adult petunia is a drought-resistant plant, in hot summer it still requires watering, and grandiflora petunia is even more demanding in this matter than multiflora petunia. Watering is carried out at the root, so as it does not damage the delicate flowers of petunias. The next day after watering the weeds are removed and the soil is loosened to avoid crust formation. But what makes petunia beautiful and bloom for a long time is a regular feeding. You should start feeding petunia in a week after seedlings planting in the ground and continue feeding by a combined fertilizer with a predominance of potassium every ten days until August. Sometimes it is possible to use organic fertilizers, for example, the infusion of mullein, or humic fertilizer.
Petunia propagation by cuttings
Spreading, double-flowered petunias and all group of calibrachoa (mini petunia) are mostly propagated by this way. Double-flowered petunia’s cutting is produced in late winter or early spring, and calibrachoa and spreading petunia’s cutting can be carried out at any time of the year under the conditions of supplementary lighting provided by fluorescent lamps and with the air temperature in the room of 70-75 ºF . Apical cuttings with 4-6 leaves are taken from a mother plant, but only two top leaves are left and pruned by half. The cuttings are planted in the same soil mixture as the seeds of petunias, but the top is covered with sand or perlite of 0.8-1 inch thick and then it is watered with a solution of fungicide. Cuttings are planted 0.6-0.8 inch apart, and the container is covered with glass. There is no need to apply a growth stimulant (e.g., heteroauxin). The most important is that the cuttings should be just cut since their ability to take root is decreased with each passing minute.
You should ensure that the soil in the greenhouse is constantly wet all the time. Cuttings should be sprayed twice a day, but there should not be damp in the container as it can provoke the appearance of mold or root rot. Spreading and double-flowered petunias take root in a week, calibrachoa petunia takes root in two weeks. When the seedlings’ roots are 0.4-0.6 inch in length, they are transplanted in separate pots with a diameter of 2 inches. The seedlings are nipped over the 4-5th leaf to enhance bushiness. Besides cut tips of shoots are excellent cuttings for rooting. If there is a need, you can nip the petunia shoots in 2 weeks. In six weeks the plants are transplanted in pots with a diameter of 4-5 inches. Care for petunia cuttings is almost the same as for the seedlings, but calibrachoa and spreading petunias require more space, so you should use hanging pots or baskets for them.
Pests and diseases of petunia
If you follow the requirements of agricultural technology, your plants are protected from both diseases and pests. But we do not live in a perfect world, so sometimes we hear complaints that petunia dries or petunia gets yellow. If you fail to comply with the rules of care for petunia, it might get affected by late blight disease, chlorosis, blackleg, gray mold that can be controlled by special drugs, but it is more important and easier to avoid these troubles observing the rules of care for plants. If the rules are followed, apart from the fungal disease, petunia may be affected by viral diseases that can’t be treated by drugs. The pests that can damage petunia are spider mites, aphids, slugs and thrips. The measures of control are well known and have been previously described.
If you want to collect the seeds of petunias, wait until they get matured on the bush. At the beginning of flowering of petunia bushes the varieties of which you want to sow in the next year, choose some of the lower buds since the formation and maturation of seeds are faster in them. The formation of buds and full ripening of seeds take about two months.
Petunia seeds are very small, their diameter is about 0.02 inch, there is around a hundred of them in the capsule. You can cut the capsule with the seeds and keep them at home, but it would be better to shake the seeds out of the capsules, put them in sachets and put down the name of the variety and the year of harvesting on each of them. Seeds become fully ripen at a room temperature in three-four months. If stored properly, petunia seeds do not lose germination capability for up to four years.
If you really want to save an especially attractive deflowered petunia, dig it out in October, cut the stems, plant it in a pot and place in a cool room to rest, but from time to time you should water it infrequently to maintain moderate soil moisture. In February, place the "sleeping beauty" on a bright and warm windowsill and recommence regular watering. When young shoots get 2-3 pairs of leaves, the leaves are cut out with a piece of stem, planted in a pot with a fertile soil with upper layer of sand, covered with foil or glass, and placed in a light shade and taken care of, watered, aerated and sprinkled as required for three weeks until shoots get fully grown roots. Then the seedlings are planted in cups and grown there until it is time to plant them in the ground.
If you do not want to have the hassle with this and want to buy and sow new seeds in spring, treat petunia as an annual plant: remove the remains of bushes from the site and dig it over.