How to Grow and Care for Potted Petunias

Petunia is not the morning glory that most people are familiar with; it is a perennial herbaceous plant of the genus Petunia. It has a long flowering period and brightly colored flowers, and is often used to decorate flower beds and other places. Nowadays potted petunias are also quite common, and the growing method is not very difficult. Below, the editor will introduce in detail the growing methods and precautions for petunias.

How to grow potted petunias

1. Choosing pots and soil

The pot should be breathable and slightly larger, and the soil should be loose and slightly acidic. Petunias are best grown in well-aerated earthenware pots with an inner diameter of 20 cm to 30 cm, with two or three plants per pot. If using less breathable purple clay pots, plastic pots, or porcelain pots, place a layer of crushed charcoal blocks or crushed hard plastic foam blocks at the bottom of the pot to enhance air permeability and drainage and prevent root rot.

2. Water control

Petunias like moisture and are afraid of both drought and waterlogging. In spring, summer, and autumn, water frequently; water as soon as the potting soil dries, and keep the soil slightly moist, but never let water accumulate. Too wet easily causes root rot, while too dry easily yellows the leaves. In winter, the potting soil only needs to be slightly moist and not dry. When watering in the north, it is advisable to often add a little ferrous sulfate to the water (500:1) to prevent the potting soil from becoming alkaline due to long-term watering with alkaline water, which causes yellow leaves and poor growth.

3. Fertilization management

Petunias like fertilizer and also tolerate poor soil. If fertilized too much or too often, they easily grow leggy and produce few flowers. When planting or repotting and changing soil, add a little bone meal or nitrogen-phosphorus-potassium compound fertilizer to the growing medium as a base fertilizer. During the seedling stage, apply a thin nitrogen fertilizer about once every 10 days. Do not apply nitrogen fertilizer again during the bud stage and flowering stage, otherwise the plants easily grow leggy and lodge, with many leaves and few flowers. It is better to apply a nitrogen-phosphorus-potassium compound fertilizer about once every 15 days, and spray the leaves once a month with a 0.2% potassium dihydrogen phosphate solution to encourage more buds and more brightly colored flowers. Do not fertilize after bringing them indoors in winter.

4. Light

With sufficient sunlight, the flowers are abundant; when brought indoors in winter, let them see more light. Petunias like light and warmth and are not cold-tolerant. The most suitable growth temperature is 15°C to 25°C. Except that at noon during the high heat of midsummer (above 34°C) they need appropriate shading, in the other seasons they should see more sunlight, and the more sufficient the sunlight, the more luxuriant the growth and the more flowers. They are best placed in a sunny courtyard, rooftop garden, south- or west-facing balcony, or windowsill.

Petunia growing methods and precautions

I. Growing methods

1. Propagation by sowing. Petunias are often cultivated as annuals. The sowing time depends on the time to market, and the actual sowing time should also be adjusted according to different varieties. Petunia seeds are very small, with 9000-10000 seeds per gram. The suitable germination temperature is 20-22°C. Use indoor pot sowing with a mixture of high-temperature-sterilized growing medium, leaf mold, and fine sand. After sowing, no soil covering is needed; just press lightly, and they will germinate in about 10 days.

2. Propagation by cuttings. This can be done throughout the year when cultivated indoors. After flowering, cut off the sprouted tender top shoots, 10 cm long, and insert them into a sand bed. The cutting medium temperature is 20-25°C. They root 15-20 days after insertion, and can be transplanted into pots after 30 days.

3. Propagation by tissue culture. Explants use seeds, leaves, and fertilized ovaries, etc. Under sterile conditions, first soak in 75% alcohol for 8 minutes, then soak in 0.1% mercuric chloride solution for 7 minutes, take them out, rinse with sterile water, and then inoculate them on MS culture medium. Small buds appear 15 days after inoculation.

Cut the small buds and transfer them to the original culture medium for subculture. After 20 days, one small bud can produce more than 10 buds. Insert the 1 cm strong buds into 1/2 MS culture medium containing 0.05-0.2 mg/L naphthaleneacetic acid. After 10 days, 100% root and become complete small plantlets.

II. Precautions

Petunias like dryness and fear moisture. During growth, they need sufficient water, especially in the high-temperature summer season. But when there is a lot of rain and the potting soil is too wet, the stems and leaves easily grow leggy; when there is a lot of rain during the flowering period, the flowers fade, easily rot, and the petals easily tear. Long-term water accumulation in the pot often causes root rot and the whole plant to wilt and die.

When do petunias bloom

The flowering period of petunias is very long, from spring to autumn, and if the winter temperature is relatively high, they can also bloom. Each petunia flower lasts a long time, blooming continuously, generally for 2 or 3 months in a row.

However, the specific flowering period will also adjust according to the sowing time. Generally, if sown in November, they can bloom in April; if sown in January, they can bloom in May; if sown in April, they will bloom in July; if sown in July, they will bloom in September; if sown in September, they will bloom in April of the following year.

The difference between million bells and petunias

1. Difference in flowers

Million bells: The flowers are smaller than those of petunias, the corolla is funnel-shaped, and the flower colors are relatively rich. The flower shape resembles a bell, so people affectionately call it “million bells”.

Petunia: The flowers are larger than those of million bells, the flowers are funnel-shaped, and the colors are white, purple, or various reds, edged with colored borders.

2. Difference in leaves

Million bells: The leaves are smaller than those of petunias, relatively smooth, oblanceolate or narrowly elliptic, with entire margins.

Petunia: The leaves are relatively large, relatively soft in texture, and ovate.

3. Difference in branches

The branches of million bells will become semi-lignified or even lignified, but petunias will not show this situation.

Petunias are long-day plants and especially like an environment with sufficient sunlight, but they should not be exposed to strong sun; a semi-shaded place is best. At the same time, petunias are not cold-tolerant and will stop growing below 4°C. Therefore, in winter, be sure to place them in a relatively warm place.