The aim of the blog is to share our knowledge of what to plant, what is flowering and what you should be doing to prepare for the next planting season!
Learn about Zantedeschias (Calla lilies)
Zantedeschsia are grown from tuberous rhizomes and as many of the new varieties are only half hardy they are usually grown in containers in greenhouses or conservatories. Many of these can then be grown outside in the warmer summer months. Zantedeschia aethiopica is however quite different to the coloured calla lilies and is a frost-hardy perennial and with care (protect from frosts by mulching) it will survive outside all year round. Aethiopicas are also moisture loving plants and can be grown in water up to 25 cms deep. The leaves of the Zantedechsias are the first to appear in late spring and followed in the summer by the goblet shaped flowers.
Cultivation
When buying Callas ensure that the rhizomes are plump (3 cms to 5 cms) in diameter (this is the minimum size we will deliver). Plant the rhizome in a container during April/May although they can be started of in March if protected from late frosts.
The potting compost should be loam based and free draining. Callas are hungry plants so ideally a generous amount of well rotted manure, covered by a layer of compost in the bottom of the pot will give them a good start. Keep the compost moist but not too wet and if you have put a layer of rotted manure in the pot you will not need to feed again until the flower starts to show.
Flowering
Feeding the plant too much before flowering will just encourage more leaf growth. Calla plants should be fed with a high potash fertiliser, in general once a fortnight. The Callas can be moved outside when the danger of frosts has passed. During flowering the calla’s should be kept well watered but it is essential not to over water. It has also been recommended in some quarters to allow the plants to dry out between watering although our recommendation would be to keep the compost moist at all times. If planting into borders choose a position that is not in full sun as this will prolong the flowering period, with containers an area of semi shade is also preferred.
Over wintering
Except for the hardy variety of aethiopica, calla lilies are only half-hardy. After flowering the foliage will die back in early autumn, if planted in a container this should be stored in a frost free greenhouse or similar over the winter. Alternatively the rhizomes can be lifted once all top growth has disappeared, dried out and stored in a cool, dark frost free area. This rhizome can then be re-potted in fresh compost in the spring (see above). Rhizomes as is their nature will increase in size and should be divided when big enough (see our notes on dividing perennials). With calla rhizomes it is essential not to break them apart, if they do not look like they will split easily leave them to grow for another year.
