Calla aethiopica are hardy to around -10C and will be fine outdoors without frost protection throughout winter in most areas. You can plant Calla aethiopica in autumn or spring, but they must be planted in the season that they are supplied while fresh. They won’t store until the following season.
— Plant between September and early December (when supplied in autumn) or between March and May (when supplied in spring). If you’re not ready to plant them as soon as you receive them, you can store them in a cool, dry place for a short while, but within a few weeks of receiving them is best and no later than early December (for autumn bulbs) or mid May (for spring bulbs). For best results, plant them as soon as possible to avoid deterioration in storage.
— Calla aethiopica bulbs can be planted directly outside in borders or patio containers.
— If you have a heavy soil or soil with a high clay content, it is a good idea to incorporate plenty of compost and some grit or sand prior to planting to aid drainage.
— Unlike other calla varieties, Calla aethiopica specifically likes heavy, moisture-retentive soils and don’t mind soils with clay content. They are often grown in damp, boggy borders or as marginal pond plants.
— Choose a position in full sun or partial/dappled shade.
— Plant the tubers shallowly, covered by around 1cm of soil with any buds or eyes facing upwards.
— Space the bulbs around 15-20cm apart from each other, they can be slightly closer in pots.
— Water them thoroughly after planting to settle them in and continue to water regularly if the soil becomes dry.
— Leave the bulbs planted in the ground throughout the year. If it is likely it will get very cold (below -10C) you can cover them with dry foliage or mulch over winter.
— After flowering, allow the leaves and stem to fully die back or turn yellow before removing it.