The Christmas Box that I wrote about last month has finished flowering but mild spring weather has brought more plants into flower in our garden, including Primroses, Lungwort, Mirabelle Plums, Perennial Wallflowers, Chocolate Vine, Daffodils, Mediterranean Spurges and Lesser Celandines.

Indoors, the current star attraction is the Chilean Nasturtium, Tropaeolum tricolor, in our north-facing conservatory. Also known as Three-coloured Indian Cress, it is a beautiful perennial climber, which grows from small tubers. In summer the plant is completely dormant but in late autumn (usually November), thin wiry shoots start to appear and gradually start to climb up any support, often reaching out to embrace nearby house plants. If kept frost free, the plant starts to flower in mid March and more and more lovely flowers are produced until mid or late May, when the whole plant starts to die back, before disappearing below ground by June. I use a good quality peat-free compost to grow my Tropaeolum tricolor, such as New Horizon or Fertile Fibre, and I keep the compost in the pot slightly moist during the growing season, then allow it to dry out completely during the summer.

Tropaeolum tricolor can grow to 3 – 3.6 metres (9 – 12 feet) tall if it is allowed to climb high enough. My plant grows to about 1.5 metres (just under five feet) tall, but that is because my plant supports are that height, and next year I plan to use taller supports.

The Chilean Nasturtium’s leaves are bright green, lobed and peltate – that is, the leaf stalk connects to the middle of the leaf. The flowers grow singly on long wiry stalks arising from the leaf axils. Each flower is about three centimetres (1.2 inches) long and the majority of the flower consists of its five reddish-orange sepals tipped with a purple band, extending backwards in a red spur. In contrast, the petals are small and greenish-yellow, but the overall effect is lovely and the three different colours give the plant its name of “tricolor“. The Strange Wonderful Things website says that the flowers “swim like schools of tropical fish throughout winter”, which I think is a lovely and very apt description.

Although it is sometimes called the Bolivian Nasturtium, the name Chilean Nasturtium is more appropriate as Tropaeolum tricolor is a native of Chile, where it grows in cloud forest, 300 to 900 metres (980 to 2,950 feet) above sea level. Further south, it will grow at lower levels in temperate forests. Here it can endure up to 10 months of drought in the summer, when it is dormant. It is generally classed as half hardy, tolerating cool conditions down to about freezing point and the RHS gives it a hardiness rating of H2. The USDA hardiness zone is 8. In its native habitat, well buried tunbers are hardy to – 8 Celsius, and this year I found a plant growing (albeit slowly) in a pot outdoors in the garden, where temperatures had reached – 3 Celsius or lower at night.

In Chile, the flowers are pollinated by a hummingbird, the Green-backed Firecrown, Sephanoides sephaniodes. But not in Norwich – I will just have to listen to their call and use my imagination when I look at the plant.

Tropaeolum tricolor can be grown from seed, but this is said to be quite tricky. It is easier to grow the plant from a tuber and I bought mine from Hethersett Plant Fair a couple of years ago. (The fairs are organised by Norfolk Plant Heritage twice a year, and are well worth a visit). Every year, new tubers are formed, so you should have a gradually increasing stock of plants. If you have any spares, you can always eat them.

The genus Tropaeolum (family Tropaeolaceae) also contains the better known Nasturtium, Tropaeolum majus, as well as the beautiful Canary Creeper, Tropaeolum peregrinum and, my favourite, Tropaeolum speciosum, known as the Scottish Flame Flower. This appreciates damp, acidic soil and it likes growing up hedges in Scottish gardens, where its fiery red flowers contrast with dark evergreen Yew foliage.