Scientific name and introduction
Zantedeschia spp. The striking white blooms of Zantedeschia aethiopoca have long been an important cut flower, and new green-tinged and different-shaped variants are increasingly important. The hybrid ‘mini-callas’, with their elegant shape and wide range of colours, continue to increase in importance as cut flowers and potted plants. The show ‘spathe’ is a leaf-like organ that surrounds the true flowers, the thick, fleshy ‘spadix’. Although often called calla lilies, these flowers are not related to the true lily.
Quality characteristics and criteria
Callas should be harvested when the spathe has opened enough so that the spadix can be seen. Flowers harvested more mature will be more susceptible to damage, and may have reduced vase-life. The flowers are normally pulled from the rhizome, and re-cut to ensure adequate water uptake. The spadix (the thick fleshy inflorescence inside the showy spathe) should be visible at the time of purchase. Watch for bruising of the fleshy stems due to packaging. If cut too tight, flowers will usually not open properly.
Grading and bunching
Quality callas have long stems, are uniform in maturity and colour, and have no defects such as damage to the spathe or spadix. Both large and mini callas are normally bunched in groups of 10. Mini callas are sometimes sleeved to provide additional protection.
Calla flowers are not ethylene sensitive, although some researchers have shown positive effects of STS pre-treatment. Contrary to popular belief, callas do not produce significant quantities of ethylene.
Callas do not require any pretreatments.
Callas should be stored at 0° to 1°C.
The flowers may be packed horizontally or in upright hampers of water packs. If packed horizontally avoid direct contact with cleats, which may damage the fleshy stems. Standard callas may bend in response to gravity unless held at the proper storage temperature.
The mini-callas have fewer postharvest problems and are generally easier to handle and use because of their smaller size.