One of the first plants I ever remember was a nasturtium, as they grew madly in my parents' garden, sprawling over vast areas. My sisters and I were fascinated by the way drops of dew would collect in the round leaves like mercury; and we loved picking the colourful flowers. The unique smell of a nasturtium leaf (which incidentally my mother maintained could be eaten on a sandwich, long before the leaves and flowers became trendy additions to salads and rice-paper rolls!) instantly recalls those childhood days. I seem to have always had them in my own garden - they self-seed from year to year and I still enjoy seeing their cheerful trumpet-like flowers every spring.
Unlike most annuals, they actually do best in poor, dryish soil - in rich, moist conditions they tend to produce enormous leaves like dinner plates - and few blooms. The single or semi-double to double flowers (which can be picked for vases) appear from late winter to the end of spring, and are usually shades of yellow, orange, red, mahogany, apricot or salmon - wonderful to spill over the edge of hot-coloured borders or walls. The original species could spread up to 3 m and was regarded as a climber - it is possible to train these on a wire fence. I rather like these rambling forms, which intertwine with other flowers, producing delightful colour effects: such as flung over a group of upright yellow Bulbine blooms, forming a carpet below the lime-green bracts of Euphorbia characias supsp. wulfenii, or climbing through a shrub such as fluffy purple-flowered Eupatorium megalophyllum.
These days there are dwarf trailing forms as well as compact sorts that can be grown in containers - one such variety is 'Empress of India' (ht 25 cm), which has intense crimson blooms and dark green leaves, and 'Peach Melba' (ht to 30 cm) has creamy-yellow flowers with orange centres. The Alaska Series has white-marbled foliage. Sow the large seeds directly into the garden in autumn. They will still flower well if grown in part-shaded sites. Avoid over-watering as this can produce fewer flowers and more foliage. Pinching out the growing tips can help produce a chubbier plant with more flowers. Nasturtiums originated in Central and South America. Watch out for aphids, which can disfigure the plants. An occasional watering with a soluble phosphorous-rich fertiliser will improve their blooming. They could be a good candidate for a hanging basket. The flowers can be cut for use in vases indoors.
The flowers of nasturtiums provide food for bees and butterfly larvae.
Best grown from seed.