Zantedeschia : Greenhouse Plants
W – warm, minimum of 13°C (55°F)
Zantedeschia aethiopica is the Arum Lily, or if you are American, Calla Lily. They originate from marshy land which dries up in the dry season when plants die down to thick rhizomes. We copy this in our, allowing plants to become dormant during the summer, although they do not have to die right down. They are best stood outside the greenhouse and just watered occasionally. Towards the end of summer they should be potted so that the rhizomes are about 5 cm (2 in) below the surface of well-drained rich loam-based . If the old plants filled the pot with roots, they can be divided. The temperature should be 13°C (55°F) at this stage. Feed plants well when their roots have reached the edges of the pot. Plants will come into flower from midwinter onwards and should be kept in warm conditions. The spathe (main flower part) of the species is pure white but Z. a. ‘Green Goddess’ is flushed with green. There are other smaller species which need warmer conditions and are started into growth during February or March. After flowering they will gradually die down towards the end of summer and these should be dried right back and only given a little drop of water occasionally to prevent total desiccation of the rhizome. They need to be stored in the warm.
Z. elliottiana from Transvaal is the Golden Calla flowering in May or June; 60-90 cm (2-3 ft) high it also has attractive silvery spots on the leaves. Z. rehmannii from Natal is a favourite of mine which grows to 60 cm (2 ft) and has a pink spathe and creamy spadix. Z. albomaculata has silver-white markings on the leaves and a tube-like spathe which is a creamy-yellow with a reddish-purple throat and rounded white spadix. There have also been some recent new hybrids which are frequently for sale in specialist bulb catalogues or from seed catalogues. Seed should be surface sown and germinated at 21°C (70°F) in the light.