Calla LilliesGeoffrey Frankcom

Zantedeschia, calla lilies, are tuberous perennials that are possibly better known to flower arrangers and florists than to hardy planters as their brightly coloured spathes are regularly seen in bouquets and arrangements. Their tropical look will certainly enhance your patio in the summer and as they are best grown in pots they can be moved during the autumn into the shelter of a greenhouse or garage for the winter. As you will have realised they are tender coming as they do from East and South Africa.
The best know species is the Arum lily, Zantedeschia aethiopica, which is also the hardiest and can be left in the garden in mild areas to overwinter. It has large glossy green leaves that can be 16″ long and complement the large waxy white spathes which appear all summer. There are a number of Z. aethiopica cultivars worth trying including Z.a. ‘Crowborough’ AGM which is extremely hardy, Z.a. ‘Little Gem’, a dwarf variety which only grows to 18″, Z.a. ‘Tiny Tim’ and Z.a. ‘White Mischief’. If planted in the garden, always ensure that they are covered with adequate insulation before the winter.

Zantedeschia albomaculata (syn. Z. melanoleuca) and its hybrids have pale yellow or pale pink spathes up to 5 inches long with speckled leaves coloured mid-green. They are all slightly tender and therefore need to be protected for the winter.

The Golden Arum, Zantedeschia elliottiana, is a large plant which has lovely heavily spotted, dark green leaves reaching to 18″ and is another plant that requires frost free conditions. There are a number of dazzling hybrids now available in a colour palette of apricot, orange, purple, red and yellow, but some of these new ones only have plain green foliage. Never mind, you just can’t have everything! Some of these hybrids worth trying include ‘Aztec Gold’ with yellow/burnt orange spathes, ‘Black-eyed Beauty’ very attractive with cream spathes and unusual black throats and with green leaves that are heavily spotted white and ‘Dusky Pink’ with its unusual rounded mauve-pink spathes and dark throats. Some of the newish introductions include ‘Moonglow’, ‘Mozart’, ‘Pot of Gold’ and ‘Red Sox’.

Finally there is Zantedeschia rehmannii or the Pink Arum which blooms in shades of white, through pink to dark purple. This plant requires a minimum temperature of 10°C. To ensure your plants flourish do not overwater them and feed them weekly with a good liquid fertiliser. As summer moves into autumn cut down on the watering as the growth reduces and then store the tubers in their pots in a cool but frost-free place. In the spring remove the tubers from their pots and cut away any dead roots and stem bases and repot in new peat based compost. Cover the tubers with compost to about 2″ and water to allow for settlement; then top the pots up with more new compost. After flowering, the plants’ foliage can be quite interesting and also can be quite dramatic, so do not be in too much of a hurry to settle them down for the winter.

First published in the Sussex Group Newsletter, Spring 2008
and subsequently in Cornucopia Issue 24
© Copyright for this article: Geoffrey Frankcom

This article was taken from a copy of Cornucopia that was published in 2009. You could be reading these articles as they are published to a national audience, by subscribing to Cornucopia.