There are PDF files available about forcing Zantedeschia:

Growing Zantedeschia for cut flower production
Growing Zantedeschia for pot plant production

Producing Zantedeschia flowers in greenhouse soil and outside in the field

In temperate regions (in the Northern Hemisphere) Zantedeschia can be forced into flower in the greenhouse from 1 April to 1 December and can bloom outside from 1 July to 1 October. In subtropical climates, a combination of greenhouse and field production can be used to realise year-round flowering. In either region, and depending on the cultivars being produced, shading to reduce light intensity by 30% will be needed during the warm period to encourage stretching. In the greenhouse, soil temperatures of 15-18°C and greenhouse temperatures of at least 15-16°C. should be maintained. Depending on light intensity, the greenhouse temperature can be allowed to reach 20 but no higher than 25°C. Soil temperatures, however, may never exceed 20°C due to the risk of damage caused by Erwinia. The production period (planting to flowering) in the greenhouse lasts 80-120 days (this range depending on the cultivar) for a spring planting. For field production in the summer, this will be 40-70 days. And for autumn greenhouse production, this will be 60-80 days. Whether year-round planting in greenhouses and outside is possible depends on the local climate conditions and the cultivar selected. In temperate regions (Northern Hemisphere), Zantedeschia can be planted in greenhouses from December to September and planted in the field from late April to mid-July. In subtropical climates, combining greenhouses and field production allows year-round planting.

Zantedeschia as pot plants

When producing Zantedeschia as pot plants, short cultivars are usually used. These are planted from December – August and grown in the greenhouse at a temperature of approx. 16˚C. Depending on light intensity, the temperature can be increased to 20˚C but no higher than 25˚C. Shading will be necessary under conditions of high light intensity. When the plants reach a height of 2-4 cm., a growth regulator is applied. These pot plants will be saleable after 9 to 12 weeks, the exact length of time depending on the cultivar.