Growing coloured Zantedeschia (Calla)

When you receive your Zantedeschia rhizome remove it from its plastic packing and ideally plant it straight away. If you cannot plant it immediately store it in a dry, cool but frost free location for up to 2 weeks.

Plant your Zantedeschia rhizome (bulb) in a 2ltr pot, 2.5cm under the surface, using free draining and good quality compost. Sometimes it is not entirely clear which way is the right way up, one side of the rhizome will be smoother than the other; the smooth side is the base of the rhizome. The top side often has small points which are the growing shoots. Water and place in a warm, humid location (16-20oC). The pot should not need watering for about another 4 or 5 weeks. To stop the surface drying out cover with damp newspaper. Over the next few weeks you may well see roots appear at the surface – don’t worry, this is normal and will eventually disappear back down into the compost.

At 20oC you should have shoots appearing after 4 weeks. At this stage the potted bulb should be moved to a slightly cooler location, 16oC during the day and a minimum of 10oC at night. The higher the light levels the better. Low light will cause the plants to grow too tall. Until the leaves fully unroll, water very sparingly, too much water will cause the bulbs to rot. Do not allow the pots to completely dry out.

As the leaves unroll more water will be needed. The plants prefer to be watered in the morning so that they are not sat in freshly wetted compost overnight. If dull days are forecast, hold of watering until brighter days come along. Once the flowers appear the plants can be watered every other day in hot weather, in cooler weather it could be a week between watering. Once the nights are frost free (Ideally 6oC+) the plants can be positioned outside in a sunny location, they suit patio pots very well. Feeding every other week with high potash plant food during the growing season is beneficial.