Madagascar Periwinkle (Catharanthus): Growing from Seed, Propagation and Care

Madagascar periwinkle (Catharanthus roseus) is a compact little shrub with glossy leaves and five-petalled flowers. It flowers non-stop from May to October and doesn’t mind heat, which makes it ideal for sunny balconies, flower beds and windowsills.

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Illustration 1. A single plant carries dozens of flowers at once.

About the plant

In its native habitat the periwinkle is a perennial; in our climate it is grown as an annual in the garden or as a perennial indoors. The flowers are white, pink, crimson or lilac, often with a contrasting “eye” in the centre. Plants grow 20–50 cm tall, and there are trailing varieties for hanging pots.

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Illustration 2. The contrasting “eye” in the centre is the plant’s signature feature.

Important: all parts of the plant are poisonous. Alkaloids used in anti-cancer drugs are extracted from it, so it is never used as a home remedy and should be kept away from children and pets.

Growing from seed

1. When: late February to March, so the plants flower in June.
2. Soil: light, loose and pre-moistened.
3. Sowing: spread the seeds and cover with 0.5–1 cm of compost, as they need darkness to germinate.
4. Conditions: 22–25 °C under film; seedlings appear in 7–10 days.
5. Once the seedlings appear, move the tray into bright light, and prick them out into individual pots at the 3–4 leaf stage.

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Illustration 3. Seedlings grow slowly at first, so don’t overwater them.

Propagation by cuttings

In spring or autumn, cut tips 8–10 cm long, remove the lower leaves and put them in water or moist compost with sand. Roots appear in 2–3 weeks. This way you can keep a favourite variety and rejuvenate an old plant brought indoors in autumn.

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Illustration 4. Periwinkle cuttings root well in water.

Care

• Light: as much sun as possible: south-facing windows, balconies, open beds.
• Temperature: 20–27 °C; below 10 °C the plant suffers. Plant out in the garden after spring frosts.
• Watering: moderate, once the top layer of soil has dried. Overwatering does more harm than a short drought.
• Feeding: every 1–2 weeks with fertiliser for flowering plants.
• Pinching out: pinch out the tips of young plants for a bushier shape and more flowers.
• Overwintering indoors: 15–18 °C, reduced watering and cutting back by a third in spring.

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Illustration 5. In balcony boxes, periwinkle flowers all summer.

Possible problems

• Yellow leaves — overwatering or too little light.
• Pale, small flowers — too little sun or feeding.
• Pests — aphids and spider mites in dry air.

In short. Sun, warmth, moderate watering and regular feeding, and the periwinkle will reward you with non-stop flowers from late spring to autumn.