Cultural information for Zantedeschia species

The genus Zantedeschia is a member of the Araceae family. Zantedeschia is the only genus in the tribe Zantedeschieae, which is in the subfamily Philodendroideae. The name Zantedeschia was first established by Spengel, but other genus names such as Arodes, Aroides, Arum lily, Pig lily, Aronskelke, Varkore, Varkblomme, Calla, and Richardia have also been used.

Listed below are the species and subspecies:

    Z. aethiopica
    Z. rehmannii
    Z. jucunda
    Z. elliottianna
    Z. pentlandii
    Z. odorata
    Z. albomaculata
    Z. albomaculata     sub. albomaculata
    Z. albomaculata sub. valida
    Z. albomaculata sub. macrocarpa

Speciation within the genus has occurred by gene change, rather than chromosome deletion.

All species are herbaceous perennials, which bear an inflorescence consisting of a spadix carrying the true male (stamens) and female (carpels) flowers (pollination is by flies) subtended by a coloured bract known as a spathe. The spathe and inflorescence are typically presented below, at or above the foliage. The spathe may vary in shape from regularly funneled or trumpet-shaped with minimal convolutions, e.g., Z. pentlandii, to a tightly folded tube with a tapering tip, e.g., Z. rehmannii. After fertilisation, poisonous berries are produced.

The genus Zantedeschia is daylength neutral, with regards to flowering, and thus would respond to year round forcing if the soil temperature was above the minimum. Zantedeschia readily acclimate to low photosynthetic photon flux (PPF) regimes.

Z. albomaculata
Z. albomaculata is widespread in its distribution across the coastal and mountainous regions of southern Africa. Z. albomaculata is deciduous in habit, and grows to 75cm tall. Colours range from creamy to straw coloured to pale yellow, and sometimes coral pink. It is green at the base of the spathe and sometimes has an open tubular spathe. It flowers predominantly in the summer months, but can be forced earlier and later in a greenhouse environment. The leaves are either immaculate or conspicuously maculate, usually oblong hastate, rarely ovate hastate, lower lobes short to triangular spreading or straped shaped.

Z. rehmannii
Z. rehmannii is a deciduous plant with narrow lanceolate leaves and cuneate at the base. The leaves being immaculate, although some of the leaves have translucent spots. Flower colour ranges in shades of creamy white, pink and red, to deep maroon, and it blooms in the summer months. The plants are hardy in the wild and increase in size yearly. Z. rehmannii are found on grassy or stony hillsides at medium to high altitudes of the Transvaal. Flowering occurs from September to February in the wild, with peak flowering between November and January. Flowering (South Island, New Zealand) outside normally commences (dependent on the prevailing weather conditions) in December and they continue to flower late March to early April, with the majority flowering between January and February.

Z. jucunda
Z. jucunda is deciduous and its growth is restricted to several areas in Africa. It has yellow spathes with a purple throat at the base of the spathe and flowers in the summer months. It has triangular hastate and spotted leaves.

Z. elliottiana
Z. elliottiana is deciduous with a yellow spathe, without a purple blotch at the base. It has a single stem growth habit, and is very robust and tall (up to 60cm), and flowers in the summer months. It has ovate-orbicular spotted leaves. This species has not been recorded in the wild with certainty and is suspected as being a hybrid in origin. However, it breeds true from seed.
Flower colour ranges from light pastels to bold colours.

Z. pentlandii
Z. pentlandii is deciduous in habit and usually has a white spathe, but there are some variations which have creamy, ivory, pale green/yellow, and yellow spathes, usually with a purple blotch at the bottom. It has oblong hastate leaves, usually without maculations. It flowers in the summer months, and grows a robust and tall (up to 60cm), plant with a single stem growth habit.

Growth and Development: It generally takes two full years of growth before a flowering sized Zantedeschia tuber is produced. Zantedeschia do not tolerate freezes, and the foliage normally dies down during late autumn - early winter.

Vegetative Growth: The key to maximizing Zantedeschia shoot and tuber growth is to maximize the leaf canopy area. Tuber growth is directly dependent on total leaf area across a wide range of temperatures and light levels.

Tuber Production Propagation of the species can be done by seed, although the propagation is limited to the true species, which have a limited range of colours. Division of tubers after lifting is a common means of increasing stock numbers. This type of propagation should not be sustained, because of the likelihood of viral and bacterial disease spread.

Lifting and curing After flowering, plants begin to turn yellow and senesce at the end of a growth cycle. A protective skin will begin to develop on the tuber exterior. This process can be accelerated by warm temperatures after lifting. Tubers are lifted from the soil by hand or a modified potato harvester. The tubers are fragile at this stage, so care must be taken not to damage them. Excess soil should be washed off and tubers are inspected for soft rot, which is easy to recognise due to its milky white tissue and a distinctively bad smell. The roots are left intact and the tubers are placed upside down on racks for curing. Curing in the field is not recommended, as unexpected frosts will damage the tubers.

Curing chambers or empty glasshouses are used to keep temperatures between 20 -24遊 for approximately 2 weeks. Air circulation is necessary to maintain humidity at 70-80%. Once curing is complete, the roots can be removed and the tubers placed topside up in boxes or trays, with dry packing material around them. Untreated dry sawdust, woodshavings or rice hulls are suitable materials .This will reduce continued water loss and shrinkage of the tubers.

Tuber Storage The duration and temperature used for storage will affect the time to flower from planting, flower stem length and productivity. Warm storage (20遊) will result in tubers being ready for replanting in six to eight weeks. Tubers can be stored for up to 10 months at 12遊, but productivity of the plants decreases with time. Tubers stored at 4遊 have a high incidence of decay after 6 weeks. If temperatures drop to freezing the tubers will be destroyed. Temperatures at 8遊 will hold the tubers in a non-sprouted state for up to 6 months. Although flower potential is sacrificed with long-term storage, it can be restored with the use of gibberelins. Tubers stored for long periods will have shorter flower stems, less leaf area, and flowers in shorter periods.

Ground preparation Zantedeschia's will grow in most soils provided they have adequate drainage. Sandy loam soils are preferred as they are free draining, lifting is easier, and the tubers require less cleaning than they would in clay.

Density Planting depth and density is widely dependent on size of tubers and expected duration in the ground.

Irrigation After planting, water is applied sparingly until the leaves unfurled. Providing the soil is adequately drained and aerated, generous amounts of water should be applied prior to and during the flowering period. Once flowering is complete, irrigation levels are reduced to discourage bacterial softrots from occurring.

Photoperiod Photoperiod does not influence flowering in Zantedeschia.

Ian Gardner
P.O.Box 56 Sefton,
North Canterbury,
South Island, New Zealand.
PH: ++64 3 3129609
FAX: ++64 3 3129629
Email: geophyte@iconZ. co.nz ; gardneri@lincoln.ac.nz