A Detailed Guide to Sowing Periwinkle Seeds, Easy for Beginners to Learn

Periwinkle (Catharanthus roseus) is much loved by flower enthusiasts for its many colors and long blooming period. Periwinkle is mostly grown from seed, though it can also be propagated from cuttings; however, seedlings grown from cuttings are not as vigorous as those grown from seed.

Periwinkle (detailed introduction)

Generally, flower enthusiasts buy periwinkle seeds directly, though some save their own seed. Here we will briefly mention the timing for collecting periwinkle seeds: because the fruits ripen at different times depending on when the flowers bloom, the seeds must be collected as they mature. Once the fruit ripens and turns black, the skin easily splits open and the seeds are lost, so seeds must be collected promptly. When you see the fruit skin turning yellow and the black seeds faintly visible inside, it is time to harvest.

1. Timing for sowing periwinkle: Periwinkle is generally sown around March to May in spring. Generally speaking, to make periwinkle bloom earlier, it can be sown and raised in a greenhouse in early spring, giving it a 20°C environment, then moved outdoors to grow once the weather warms up.

2. Sowing medium: The medium is best prepared with peat + perlite at a ratio of 3:1. Leaf mold can also be used. Water thoroughly with a 500-600 times dilution of carbendazim solution (for sterilization), and place the seedling container in a south-facing sunny spot.

3. After sowing, cover with a thin layer of sandy soil; do not let the seeds be exposed directly to light. Water thoroughly with a fine watering can, cover with plastic film or a straw mat to keep the soil moist, and seedlings will emerge in 7-10 days.

4. Management after emergence: After periwinkle seedlings emerge, gradually increase light exposure. Because periwinkle seedlings grow slowly, they grow faster once the temperature rises. Thin them out in time (that is, remove the weak, small seedlings; proper thinning helps the seedlings grow strong).

Sowing and Raising Periwinkle Seedlings, How to Grow Periwinkle

Periwinkle is also known as ririchun, riricao, ririxin, sanwanhua, sishichun, shizhonghua, yanlaihong, and others. It is a subshrub in the genus Catharanthus of the Apocynaceae family, with high ornamental value, but the whole plant is toxic and requires careful attention. After accidental ingestion, it can cause symptoms such as reduced white blood cells, reduced platelets, muscle weakness, and paralysis of the limbs. Let us take a look at how to grow periwinkle and the precautions to take!

Growth Habits of Periwinkle

Periwinkle is native to the Mediterranean coast, India, and tropical America. Its cultivation history in China is not long, mainly in areas south of the Yangtze River, and it is fairly commonly cultivated in Guangdong, Guangxi, Yunnan, and other provinces (autonomous regions), used for potted plants and planter boxes. It likes high temperatures and high humidity, tolerates partial shade, and is not tolerant of severe cold. The most suitable temperature is 20-33°C. It likes sunlight, dislikes wet conditions, and fears waterlogging. It can be grown in almost any soil, but saline-alkaline soil is not suitable; sandy or humus-rich soil with good drainage and ventilation is best. Its flowering and fruiting periods last almost all year round.

Propagating Periwinkle from Cuttings

Periwinkle cuttings are mostly taken from April to July. When propagating from cuttings, choose healthy, pest-free young shoots from mature plants as cuttings. Generally, take young shoots 10-12 cm long from the top of the plant, with a cutting length of 5-7 cm being suitable. Use a mixed medium of plain sand, vermiculite, and peat for the cuttings. Wrap a small ball of mud around the base of the cutting, insert it into a cold frame at a room temperature of 20-24°C, and roots will form after about 20 days. Once the cuttings have rooted and survived, they can be transplanted into pots. Because plants grown from cuttings are less vigorous than seedlings grown from seed, this method is rarely used in cultivation.

Sowing and Raising Periwinkle Seedlings

1. Seed collection time: Because periwinkle fruits ripen at different times depending on when the flowers bloom, the seeds must be collected as they mature. Once the fruit ripens and turns black, the skin easily splits open and the seeds are lost, so seeds must be collected promptly. When you see the fruit skin turning yellow and the black seeds faintly visible inside, it is time to harvest.

2. Sowing time: The suitable temperature for periwinkle seed germination is 20-25°C. It is usually sown and propagated from March to May, mostly grown as an annual. To make it bloom earlier, it can be sown and raised in a greenhouse in early spring, giving it a 20°C environment, then moved outdoors to grow once the weather warms up.

3. Seedbed preparation: Choose a spot for the periwinkle seedbed that is high and well-drained, south-facing and sunny, and well-drained. The medium is best prepared with peat + perlite at a ratio of 3:1. Leaf mold can also be used. Water thoroughly with a 500-600 times dilution of carbendazim solution. Once slightly dry, loosen and level the soil, and make beds 1.2 m wide.

4. Sowing technique: Broadcast periwinkle seeds at about 1000 seeds per square meter. After sowing, cover with a thin layer of sandy soil; do not let the seeds be exposed directly to light. Water thoroughly with a fine watering can, cover with plastic film or a straw mat to keep the soil moist, and seedlings will emerge in 7-10 days. After emergence, remove the film or straw mat and gradually increase light exposure. Seedlings grow slowly at first, then faster once the temperature rises, so thin them out in time. To prevent periwinkle damping-off, spray with an 800 times dilution of chlorothalonil or thiophanate-methyl once a week for 2-3 consecutive weeks.

How to Grow Periwinkle

1. Soil: Periwinkle prefers fertile, well-drained soil and tolerates poor soil, but must absolutely avoid soil that is on the alkaline side. In compacted, poorly aerated clay soil, the plant grows poorly, the leaves turn yellow, and it does not bloom.

2. Sunlight: Periwinkle is a light-loving plant. During the growing period it must have sufficient sunlight, so the leaves are deep green and glossy and the flowers are brightly colored. If grown in shade for a long time, the leaves turn yellow and drop.

3. Temperature: Periwinkle likes a warm, slightly dry, and sunny environment. The suitable growing temperature is 18-24°C from March to July, and 13-18°C from September to March of the following year. In winter, the temperature should not be lower than 10°C.

4. Watering: Periwinkle dislikes wet conditions and fears waterlogging, so do not water the pot soil too much; excessive moisture affects growth and development. Especially for plants overwintering indoors, watering should be strictly controlled, and it is better to keep them dry, otherwise they are very prone to freezing damage. For outdoor cultivation, during heavy summer rain showers, pay attention to timely drainage to avoid waterlogging that causes entire patches to die.

5. Fertilizing: When fertilizing periwinkle, you can alternate a compound fertilizer and a liquid fertilizer once every ten days. Also try to spread a layer of base fertilizer at the bottom of the periwinkle pot soil to ensure the nutrient content of the pot soil.

6. Pests and diseases: The periwinkle plant itself is toxic, so it is relatively resistant to pests and diseases. The main diseases during the seedling stage are damping-off, gray mold, and others. In addition, prevent fertilizer burn and pesticide damage during the seedling stage. If these occur, immediately water thoroughly with clean water, increase ventilation, and reduce the damage.

7. Pruning: Periwinkle is a herbaceous plant and is quite suitable for potted cultivation, but be careful not to let the plant grow too tall, which would affect indoor decoration and ornamental value. Therefore, after the plants survive in pots, pinch them back several times to encourage more branching and more blooming. After flowering, remove the spent flowers.

How to Sow Periwinkle, Periwinkle Planting Tips

Periwinkle is also called golden marigold. It has many flowers and a particularly long blooming period, blooming from spring all the way to autumn. If you are also someone who loves growing flowers, then take a look at the recommendations we share below on how to sow periwinkle.

I. How to Sow Periwinkle——Raising Seedlings

Good flowers come from good seedlings. Periwinkle seeds are not large in appearance, and the plant itself is a perennial variety that blooms in all four seasons. So the conditions for raising seedlings are fairly flexible, and the recommended time for raising seedlings is from January to April. After sowing and raising seedlings in seedling cells, make sure the temperature is maintained at around 20°C, which ensures successful seed germination and achieves the seedling-raising effect.

II. How to Sow Periwinkle——Transplanting into Pots

After the cell seedlings have grown, once the leaves have grown to two or three true leaves, they can be transplanted into pots. It is best to complete the potting in one step, thus avoiding a second repotting.

III. How to Sow Periwinkle——Light

Periwinkle is a sun-loving plant, so both its blooming and growth require plenty of sunlight. Sufficient light ensures the plant will not grow leggy with excessive leaves. Insufficient sunlight instead causes poor leaf growth.

IV. How to Sow Periwinkle——Temperature

Periwinkle is sensitive to temperature, especially to low temperatures. If you want to grow periwinkle well, temperature control is also necessary. If periwinkle is grown in the Yangtze River basin, you can consider using insulation measures, because at temperatures below 15°C, periwinkle will stop growing.