Renowned for their bright flowers and decorative round leaves, nasturtiums (Tropaeolum genus) are a great addition to the garden. These gorgeous, cottage-style flowers are fairly easy to grow, they smell wonderful, and many varieties are completely edible.
One of the most popular nasturtium species is Tropaeolum majus, also known as a garden nasturtium, Indian cress, or monks cress, with a wide range of cultivars. Other notable species are Tropaeolum peregrinum, Tropaeolum speciosum and Tropaeolum minus which also offer many different varieties and types.
Growing Nasturtiums
Nasturtiums require minimal care. These beautiful edible plants even like being a bit neglected and thrive even in poor soil.
Although considered perennials, nasturtiums are annuals in cooler climates, meaning that they end their life cycle in one year. They’re mostly slightly tender plants which grow and flower up until the first frost or freeze.
Position & Sun For Nasturtiums
Nasturtiums prefer bright, full sun positions. They will tolerate partial shade but will produce significantly fewer flowers. To avoid heat stress during very hot summers, find a place that will give them dappled light during the hottest part of the day.
These plants tolerate poor soil, but the soil for nasturtium should have a good amount of drainage since they don’t like ‘wet feet’. Well-drained soil and regular watering during a hot, dry season will be more than enough to keep nasturtiums healthy and beautiful.
Nasturtiums don’t require fertiliser. Actually, too much fertiliser can promote foliage growth while leaving the plant with significantly fewer blooms.
Sowing Nasturtiums
Nasturtiums are one of the easiest plants to grow from seeds. They grow quickly and it takes about 10 to 12 days for seeds to germinate. The ideal temperature for seed germination is around 12-23°C (55–75ºF).
Nasturtium seeds are quite big and easy to handle. Since nasturtium seeds need darkness to germinate, place the seeds at about 1.5 cm (1/2 in) in the soil. Keep the soil constantly moist.
Nasturtium seedlings don’t handle being transplanted well, it’s recommended to sow them directly in their permanent place. If you’re planting them outside, sow them when all danger of frost has passed.
If you want to start nasturtiums indoors, you can sow seeds as early in the spring as possible. They handle pots and containers very well, so you can relocate the plant outside once the weather conditions are favourable for their growth.
What Parts of Nasturtiums are Edible?
Not all plants from the Tropaeolum genus are edible. Only the cultivars of Tropaeolum majus are safe for consumption and can be put to culinary uses.
Leaves, buds and flowers of garden nasturtium (T. majus) are edible. Both leaves and flowers have a peppery flavor, similar to mustard or watercress, and they’re often used to garnish salads. You can also use them in a soup, risotto, or stir fry.
Nasturtium seeds have an even hotter taste than leaves and flowers. You can ground them to powder and use as a substitute for pepper.
Besides this, the plant has a nutritive value – it’s rich in vitamin C and holds a great amount of lutein.
When and How to Harvest Nasturtiums
The best time for harvesting nasturtiums is morning. Pick the flowers as soon as they open. If you pick them during the hottest part of the day, you risk getting a slightly unpleasant, sharp flavour.
Harvested flowers and leaves should be consumed as soon as possible. They have a tendency to wilt if kept around for too long. Store as you would a salad in the fridge.
If you leave some flowers unpicked, nasturtiums will produce lots of new plants since they’re self-seed.
Different Types of Nasturtiums
With so many beautiful nasturtium cultivars and hybrids available, there’s something for everyone’s taste and needs.
Before starting nasturtium in your garden, be sure to check the characteristics of each cultivar and ask yourself what type of growth form would you prefer?
Then you can choose between the trailing, climbing, bushy type, or even dwarf varieties. In addition, some varieties give a particular interest with their flowers, while others are extremely decorative thanks to their lively variegated foliage.
Take a look at some of the most beautiful Tropaeolum species and cultivar with different types of growth habits and various shapes.
Mounding/Bush Nasturtium Varieties
If you prefer nasturtiums with a round, compact shape, pay attention to these cultivars. They fill garden beds with lots of flowers and are often used as borders. These varieties are also considered as semi-trailing, since their stems spillover, so they look gorgeous in hanging baskets, window boxes or containers.
‘Empress of India’ (T. majus) – Vermilion-red blossoms and dark blue-green foliage.
Nasturtium ‘Alaska’ (T. majus) – This nasturtium series is highly prized; it even gained the Royal Horticultural Society’s Award of Garden Merit. The foliage is variegated, while the flowers come in many different shades.
‘Summer Gown’ (T. majus) – Deep burgundy-purple flowers that become bluer as summer progresses.
‘Vesuvius’ (T. majus) – Salmon rose petals and bright green leaves
‘Whirlybird’ (T. majus) – Bright colors of cherry, tangerine, scarlet, mahogany, lemon, and cream. This cultivar gained the Royal Horticultural Society’s Award of Garden Merit.
Nasturtium Climbing / Trailing Varieties
These varieties produce mainly horizontal growth. If you give them some kind of support, they can be trained to climb (against trellis, walls, fences…) giving a beautiful vertical interest. But if you leave them without support, they can trail beautifully and be treated like some kind of ground cover.
‘Purple Emperor‘ (T. majus) – Purple to dusty pink flowers
The Canary Creeper (T. peregrinum) – Exotic yellow flowers that resemble the feather wings of a canary
‘Gleam Salmon’ (T. majus) – Apricot flowers with a deep-red center
‘Double Gleam Scarlet’ (T. majus) – Bright red flowers
Flame nasturtium, Flame Creeper (T. speciousum) – Exotic, long-spurred red flowers. Good as a ground cover.
‘Hermine Grashoff’ (T. majus) – Bright double orange-scarlet flowers and pale green leaves. The cultivar gained the Royal Horticultural Society’s Award of Garden Merit.
Nasturtium ‘Moonlight’ (T. majus) – Pale creamy yellow flowers
Tropaeolum tuberosum var. lineamaculatum ‘Ken Aslet’ – Climber with yellowish, red-streaked tubers and blue-green leaves.
Wreath nasturtium (T. polyphyllum) – One of the hardiest Tropaeolum species, native to the mountains of Chile and Argentina. It features grey-green foliage and bright yellow flowers.
Blue nasturtium (T. azureum) – Also native to high elevations in Chile, blue nasturtium is a summer-dormant herbaceous plant. It produces gorgeous cobalt blue flowers.
Three-coloured Indian cress (T. tricolor) – Another winter-growing, hardy species. It blooms with red, purple, and yellow tubular flowers.
Nasturtium Dwarf Varieties
If you love miniature plants, then you’ll be thrilled with dwarf nasturtiums. These grow up to 30 cm (12 in) in height and have flowers 3 cm (1.2 inches) across or less. Dwarf varieties are great for growing in small gardens and containers.
‘Ladybird Rose’ (T. minus) – Dusty-pink flowers
‘Black Velvet’ (T. minus) – Mahogany-colored, velvety blooms
‘Ladybird Cream Purple Spot’ (T. minus) – Gentle cream blooms with distinctive dark purple central markings.
‘Phoenix’ (T. minus) – Butterfly-like flowers with sawtooth petals in shades of red, orange and yellow
‘Baby Rose’ (T. minus) – Deep rose flowers and compact mounding habit.
‘Alaska Apricot’ (hybrid) – Pale green leaves variegated with white patches, coral red flowers.