1. The basin should be slightly permeable and the soil should be loose and slightly acidic. Petunias should be planted in clay pots with good air permeability and an inner diameter of 20 ~ 30 cm, with two or three plants in each pot. If purple sand pots, plastic pots and porcelain pots with poor air permeability are planted, a layer of broken charcoal blocks or broken hard plastic foam blocks can be placed at the bottom of the pots to strengthen ventilation and drainage and prevent root rot. It can also be planted in plastic hanging pots (each pot 1 plant) and hung on the balcony or window. It is best to use loose and fertile slightly acidic sandy loam for planting, and the culture soil can be prepared from humus, vegetable garden topsoil, sand or perlite at the ratio of 5∶4∶ 1, and the pH value is preferably 5.8 ~ 6.2. If the pH value exceeds 6.6, it will inhibit the absorption of iron by roots and lead to yellowing of leaves. Avoid using heavy clay and saline-alkali soil.
2. Sowing and cutting are easy to propagate, and there are many branches that need pruning. Petunia is generally propagated by sowing method, which blooms in spring, summer and autumn, and in autumn, winter and spring. Its seeds are very small, so mix them with fine soil first and sow them thinly. After sowing, cover it with glass or plastic film, place it in a semi-shady place, and often spray water to keep it moist. 18℃ ~ 24℃ can germinate in one week. After emergence, remove the glass, transplant the seedlings once when the height is 2 cm, then plant them in a pot when the height is about 8 cm, and pick the core to promote their branching. Pick the heart two or three times in the future to make the plant low, with many branches and flowers. The picked branches can be used for cutting propagation. The method is to use chopsticks to make a hole in the plain soil, insert it into it for compaction, and put it in the shade of the semi-reason, and often spray water to keep it moist. Spring and autumn 10 ~ 15 days can take root, 10 ~ 15 days later can be planted in pots. The survival rate of cutting in summer is low, so it must be covered with plastic film for insulation in winter. After Petunia blooms, several flowers of each variety are selected to bear seeds, and the rest flowers are cut off or shortened with pedicels to promote multi-branch and multi-flowering.
3. Water moderately to prevent drought and flood, apply more phosphorus and potassium and less nitrogen fertilizer. Petunia likes wet, but is afraid of drought and waterlogging. Water frequently in spring, summer and autumn. When the pot soil is dry, it is better to keep it slightly wet, but it must not be flooded. Too wet will rot the roots, too dry leaves will turn yellow, and the pot soil will be slightly wet in winter. When watering in the north, ferrous sulfate (500∶ 1) should be often added to the water to prevent the potted soil from being alkalized, and the yellow leaves will not grow well if watered with alkaline water for a long time.
Petunia likes fat, but also bears barren. Too much fertilization and too hard work make it easy to grow white and spend less. When planting or changing soil, bone meal or NPK compound fertilizer can be added to the cultivated soil as base fertilizer. Apply weak nitrogen fertilizer once in the seedling stage of 10 day, and don't apply nitrogen fertilizer again in the bud stage, otherwise it will grow white easily. With more leaves and fewer flowers, it is advisable to apply 1 time NPK compound fertilizer in about 05 days, and spray 0.2% potassium dihydrogen phosphate solution on the leaves once a month to promote more beautiful buds and flowers, and no fertilizer is applied in winter.
There is plenty of sunshine, lush flowers and plants, and more indoor light in winter. Petunia likes light, warm and not cold. The optimum growth temperature is 65438 05℃ ~ 25℃. In addition to the high temperature (above 34℃) at noon in midsummer, there should be more sunshine in other seasons. The more sunshine, the more lush growth and more flowers, so it should be placed in sunny courtyards, roof gardens, balconies and windowsills in the south or west. Before and after the first frost is moved indoors, it should be placed on the window sill in the south or west to see more sunshine. Keeping the room temperature above 2℃ can safely overwinter, can continue to grow above 10℃, and can bloom above 15℃. The following spring, she went out around Tomb-Sweeping Day, turned over the pots and changed the soil, cut it again, applied dilute nitrogen fertilizer once or twice, resumed growth and blossomed again. After two overwintering, the old plants gradually decline, and can be eliminated in autumn and replaced with seedlings propagated in spring and autumn of that year.