Tropaeolum minus. The flat-faced flowers of Black Velvet Nasturtium face upwards, and are held above the pale green foliage. The flowers themselves are such a rich, dark shade of mahogany, they appear almost black from any distance. This compact Nasturtium is perfect for container growing, and it blooms continuously throughout the summer. The edible flowers look sensational as garnishes, and bring a peppery kick to salad mixes.
The annual flowers in this group have been called many colourful names, including Bitter Indian, Canary vine, Canary-flower, Indian cress, Monk’s cress, Flame flower, and plain old garden nasturtium. Nasturtiums thrive in poor to average, slightly acidic, well-drained soil. If growing in full sun, consider using some rocks around the plants to prevent their roots from getting too hot. In partial shade, plants tend to have larger leaves and a more sprawling habit. Keep watered during dry weather, and do not fertilize. Continue reading below for more tips on how to grow nasturtiums from seed as companions for Brassicas, cucumbers, melons, radishes, and tomatoes.
Tropaeolum majus & T. minus
Season & Zone
Exposure: Full sun to partial shade
Sow indoors in peat or coir pots 2-4 weeks before the last frost date. Better yet, direct sow from 1 week after last frost and repeat at 2 week intervals into early summer. Optimal soil temperature for germination: 12-18°C (55-65°F). Seeds will sprout in 7-12 days, perhaps longer outdoors.
Sow seeds 5mm – 1cm (¼”-½”) deep. If starting indoors, provide darkness during germination, followed by bright light. Space smaller varieties 15-30cm (6-12″) apart, and the big ones like Tall Single 60-90cm (24-36″) apart.
Nasturtiums thrive in poor to average, slightly acidic, well-drained soil. Keep watered during dry weather, and do not fertilize. If aphids infest nasturtiums, cut off the infested growing tip and destroy it. Otherwise, a quick jet of water from the hose will dislodge and kill aphids.
Nasturtiums make a good trap crop for aphids, and they deter whiteflies, cucumber beetles, and attract predatory insects. It is a good companion for Brassicas, cucumbers, melons, radishes, and tomatoes.
More on Companion Planting.