Celosias were first introduced from the Far East in the Sixteenth century before there were more than a handful of greenhouses so were not easy. Once the heated greenhouse became available then this relation of Amaranthus became immensely popular with over sixty species discovered and introduced from Africa, Asia and the Americas. Then they generally declined until today only a few are available, for summer bedding as Crested Cockscombs with their peculiar ‘sculpted’ flower heads and the more delicately plumed Prince of Wales Feathers.
However it’s as greenhouse subjects these Half-hardy annuals are most suited. Just too tender to do well outdoors during our cooler damper summers they love a cool greenhouse. Here they make excellent pot plants rewarding us with many months of display of their unusually bright red, orange and yellow rather plastic looking blooms.
In particular though I’ve been taken by the new F1 hybrids such as Dragon’s Breath. With these you get tremendous impact with foliage colour enhanced later as the gorgeous pampas grass like plumes emerge. Moreover from a small good looking foliage plant in late spring this continues to swell as a stunning display of colour right up till it dies away, though then looking respectable as semi-dried off specimens till into the New Year.
You can start off many varieties from seed in late winter in a warm propagator and treat much as Petunias and other tender bedding. However for the latest and ‘best’ such as Dragon’s Breath you need buy seedling plants in spring, keeping these warm and potting up as they grow. Celosias are easy, happy in most reasonable potting composts and needing only moderate watering and light feeding. However they are rather tasty to slugs so take precautions. (Indeed several species have been eaten,, much as the related Amaranthus -though this cannot be recommended for ‘floral’ varieties.)
Although needing plenty of light to do well if it’s too hot and bright this may fade their colour. Because of their long season they are thus better moved somewhere light is reduced or diffused from early though to late summer, in amongst other foliage plants works and contrasts well. Then move them to lighter positions for autumn and early winter.
Celosia given their name describing some as ‘ dry & burnt’ which early species were said to somewhat resemble- perhaps they meant frosted?