Description
The Cosse Violette (also known as Blue Coco or Violette de Belgique) is a visual feast for any vegetable garden and a top performer in the UK’s slightly unpredictable climate. It is arguably the best “stringless” climbing bean available, valued for its vigorous growth and the dramatic contrast between its rich purple pods and lush green leaves.
Cosse Violette Purple Climbing Bean
| Feature | Details |
| Type | Phaseolus vulgaris (Climbing/Pole Bean) |
| Pod Size | Slender, cylindrical, and very long (20cm – 25cm) |
| Colour | Striking deep purple (turns green when cooked) with black seeds |
| Flavour Profile | Sweet, nutty, and exceptionally tender, with zero stringiness |
| Growth Habit | Extremely vigorous climber (easily reaches 2m – 3m) |
| Best For | Steaming, blanching, freezing, or fresh in salads |
Description
This is a truly superior climbing French bean. While standard green climbing beans can quickly become stringy, the Cosse Violette remains tender even when pods get quite large. The initial sight of the smooth, deep violet-purple pods is stunning. But the magic happens in the kitchen: as soon as the purple pods are heated, they transform into a vibrant, deep green. This is a massive hit with children and makes cooking a spectacle. The plant produces delicate purple flowers, enhancing its beauty, in fact, it doesn’t look out of place in the back of a flower border.
UK Growing Tips
This variety is highly robust and performs exceptionally well in cooler British summers, often out-yielding other green climbing varieties. Its vigorous nature means it uses vertical space effectively, perfect for small plots.
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Plant: Once the risk of frost is gone (late May/early June), transplant your hardened-off seedlings. Dig a good hole and backfill with some compost or well-rotted manure. Space plants around 15cm–20cm apart.
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Build a Strong Frame: You cannot grow this bean without support. It grows fast and heavy. A classic 2.4m (8ft) A-frame trellis or a sturdy wigwam made of bamboo canes is essential. Secure the canes well. As the vines grow, you may need to gently guide the young shoots toward the canes.
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Blackfly Alert: Watch for black aphids, which can quickly cluster around the soft growing tips and under leaves. Plant Nasturtiums or Summer Savory nearby to help repel them, or blast them off with a strong jet from a hose.
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The Nitrogen Trick: After harvesting, cut the stems back but leave the roots in the ground. Bean roots are excellent at adding nitrogen to the soil, naturally fertilizing the spot for next year’s crop.
Usage & Culinary Notes
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Harvest Daily: To encourage continuous cropping, pick the pods regularly once they are 15cm–20cm long. This stops the plant from putting all its energy into seed production and keeps it pushing out new flowers.
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The Purple Magic Trick: Do not be dismayed when your beautiful purple pods turn green! This is normal. To preserve maximum colour for visual effect, blanch very briefly (30–60 seconds) in boiling water and plunge immediately into ice-cold water to “set” the green.
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No String Work: Because they have no “strings” along the side seam, they require only “topping and tailing” before use—no tedious pulling is needed. This makes prep work fast.
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Freezing Power: This is a superb variety for freezing. Simply blanch, cool, and pack. They retain their sweet flavour and snap texture incredibly well for winter use.
