Nymphaea: Greenhouse Plants
W – warm, minimum of 13°C (55°F) / T – tropical, minimum of 18°C (65°F)
Very few people think of landscaping their greenhouse or conservatory but this is perfectly feasible, and water can be included which opens up the possibility of growing temperate and tropical waterlilies. The culture of these is very similar to growing them in outdoor ponds; they should be potted into rich loamywith a layer of gravel below and on the top to prevent the soil from floating away. This should be done in spring and the pots sat in the water so that to begin with they are only just covered. As they grow, which ideally requires a temperature of 18-21°C (65-70°F), they can be gradually lowered so that the fully grown leaves float on the surface. If you cannot raise the temperature sufficiently wait until the natural temperature is higher. For the winter when they are dormant one is supposed either to drain the water off or lift the tubers and store them in damp sand. I have always got away with simply leaving them in the water at a minimum of 10°C (50°F) with good results. N. capensis is the Cape Blue Water Lily from South Africa. Flowers are a glorious blue and stand 13 cm (5 in) above the water. N. stellata the Blue Lotus is lavender-blue with a golden centre. There are several hybrids; N. X ‘St Louis’ is a lovely lemon colour. Propagation is by dividing the tuber at potting time. Pot up small pieces and when new plants have been formed remove these from the old piece of tuber and grow on. Some of them produce small plantlets around the leaf stalk which can be pulled off and potted up. Seed can be sown in pans of just covered by water at 21°C (70°F).