The king of the perennial border. Traditionally tall, delphiniums stand majestically at the back, towering above lowing growing subjects. While we think of them as being mainly ‘blue’, an increasingly varied range of shades and colours are now available. These fantastic blooms look magnificent as the centre to large indoor arrangements.
How to Sow and Grow Delphiniums
They do well in a wide range of soils, as long as they do not become waterlogged in winter.
Sow indoors to flower the same year, 0.5cm(1/4in) deep, in a tray of compost. A temperature of 15-20°C(60-68°F) is ideal. Keep moist. Seedlings usually appear in 21-42 days. Transplant individually when large enough to handle to 8cm(3in) pots (always hold seedlings by a leaf, never by the stem). Gradually accustom young plants to outside conditions before planting out 45cm(18in) apart, when frosts are over.
Sow outdoors, for ease, where they are to flower the following year, in a seed trays of individual pots of compost 0.5cm(1/4in) deep. Pot on seedlings to larger pots if required before planting out to flowering position in autumn 45cm(18in) apart.
Remove faded flower spikes to encourage a further show of colour. Protect newly established plants from slugs. Taller types will need support to help them stay upright.