Calla lily: profile, plants & propagation

The calla lily is an exotic yet very popular plant for indoors and outdoors. But what exactly is behind this plant?

The calla lily (Zantedeschia aethiopica) and its hybrids originate from the swamps or mountain regions of South Africa and are characterised by their elegantly shaped flowers. Keep reading to find out what makes calla lilies so special and how to plant calla lilies in the UK.

Calla lily: origin and characteristics

The calla lily comes from South Africa where, depending on the species, it grows in tropical swamp meadows, on river banks or in the cooler mountain regions. In the rainy season, there is enough water available there for it, while in the dry season it dries out completely and only the tubers survive. The plant, which is also known as the Arum-lily, belongs to the arum family (Araceae) and the genus Zantedeschia, which comprises a total of only eight species. Although referred to as lilies, they are not in fact related to the lily family (Liliaceae). The ornamental plants are a popular flower decoration for indoors on the windowsill and outdoors in the tub — on the terrace as well as on the balcony – or in the flower bed. The plant, which grows up to 80cm high, is also grown commercially as a cut flower.

The exotic calla is characterised by its elegant flowers, each of which is a white or brightly coloured, cup-shaped bracts with a bulb-like, elongated flowerhead. The fruits of the calla lily are green or orange berries, which in turn contain seeds. Arrow-shaped, strong, dark green leaves sprout from the tubers, some of which have light spots depending on the variety.

When do calla lilies bloom?

The characteristic, bulb-shaped calla lily flowers with the cup-shaped bracts appear as soon as early spring from January to April. Late-flowering varieties open their flowers only between May and August. In addition to the classic white bracts, there are now also numerous colourful bracts. Very popular are, among others, calla lily varieties in cream, yellow, orange and pink – and even purple, red or black.

What is the significance of the calla lilly as a flower?

The name of the calla comes from the Greek and means something close to “physical beauty”. And it is not for nothing that this exotic flower with its unique flower shape is still a symbol of beauty today. In addition, the calla lily is regarded as a flower of purity, sympathy and as a lucky charm. Because of the cup-shaped flower, the plant also stands for joy and for celebration. Nowadays, a bouquet of callas expresses loving attention, admiration and grace. At weddings, the white-flowered calla symbolises purity and is often used in the bridal bouquet or as a church decoration. The white flowering calla also finds its place in funeral floristry as a flower arrangement or grave decoration as a sign of eternal life.

Plants similar to the calla lily

Zantedeschia aethiopica is easily confused with similar looking plants. These include the peace lily (Spathiphyllum), anthuriums (Anthurium scherzerianum and Anthurium andreanum) and the hardy native water arum (Calla palustris). All these plants, just like the calla lily, belong to the arum family (Araceae). The plants all have the typical bulb-shaped, elongated flower surrounded by a bract. While this surrounds the calla lily flower in a cup or funnel shape, it is elliptically pointed in the monocot and heart-shaped in the flamingo flower. The calla lily not only includes the plants of the genus Zantedeschia. In addition, there is a separate genus of calla, which includes, for example, the water arum or wild lily.

Planting calla lilies

The calla lily can be planted and cared for at home without too many problems if a few points are taken into account. Find out everything you need to know about planting the exotic calla lily below.

The right location for calla lilies

The calla lily needs a sunny to semi-shady location both indoors and outdoors at temperatures around 20 °C. The calla lily not only feels at home on the windowsill at home, but also on the balcony, on the terrace and in the flower bed. The location should also be protected from wind and the blazing midday sun. Humidity of 65 to 75 % is optimal. In addition, the plant has adapted its growth phases to rainy and dry seasons, which must be taken into account when caring for and overwintering the plant. You can read the details in our articles on calla lily care and one on overwintering calla lilies.

The substrate should be loose, well-drained, sandy, humus-rich and rich in nutrients. A mixture of sand and potting soil enriched with pine bark or another organic structural material is optimal. This gives the planting substrate a good and stable structure. For planting, a nutrient-rich flower compost such as our Plantura Organic Flower Compost is ideal. It has good nutrient stores due to compost and clay minerals, thereby covering the high nutrient requirements of the calla lily during the flowering period.

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When is the best time to plant calla lilies?

It is best to plant the calla lily, which has overwintered as a bulb and is now to be potted up, in spring between March and May. In this case, the calla lily can be started indoors from a temperature of 15 to 18 °C. If you want to plant the calla directly outdoors, you should wait until the end of May until the last frosts have passed.

Sowing and planting

Sowing calla lilies is laborious and time consuming, as it takes several years for the plants to flower for the first time. Seeds can be obtained either from garden shops, swap meets or from your own calla lily if it has been pollinated. Sowing is possible indoors from January. To do this, prepare a seed tray with sowing soil. The seeds are then sown thinly and covered with a light layer of soil. Place the trays in a warm place at around 20 °C to 22 °C and keep the substrate moist. It can take a few weeks before the first seedlings appear.

Before planting the calla lily seedlings, light garden soil should first be mixed with some mature compost or nutrient-rich potting soil. Then insert the tubers or rhizomes about 10cm deep into the soil. Make sure that the root-forming side is pointing downwards and the tip is pointing upwards. Then fill the planting hole with soil, press it down and water everything well. Depending on the variety, keep a planting distance of at least 40cm in the flower bed. Outdoors, damp places are ideal, such as the edge of a pond. The calla lily tubers can be buried together with a planting basket. This is then conveniently dug up in autumn to overwinter the tubers dry and frost-free.

When planting in pots, make sure that you integrate a good drainage layer in the lower part of the soil. In addition, the pot should be heavy enough, as Zantedeschia aethiopica in particular grows very tall even in a small pot and is easily blown over by the wind. If necessary, the planter can be weighted down with gravel.

Propagating calla lilies

The best and easiest way to propagate calla lilies is to divide the rootstock of older specimens. This is best done during repotting, when you dig up the plant anyway.

• Carefully dig up the rootstock and divide the tuber with a sharp knife. Each tuber should have several buds.
• Pot the tubers 10cm deep.
• We recommend using a mixture of sand and potting soil — for example, our Plantura Organic Flower Compost. It contains coconut, wood fibres and crushed expanded clay for a loose structure, lime and magnesium fertiliser as well as a mainly organic bio-fertiliser to provide the plant with sufficient nutrients.
• Freshly planted tubers need only moderate watering. As soon as new shoots have formed, water more.
• Young callas develop best at about 20 °C in a bright place, but protected from direct sunlight.

Tip: the flowers of the calla are primarily pollinated by beetles. So you can harvest your own berries especially if your calla lilies spent the summer outdoors. The seeds from the macerated berries then usually germinate without problems when they are fresh. Note here that Zantedeschia aethiopica is self-sterile.

Are calla lilies poisonous?

Yes, calla lilies are poisonous, both for humans and animals. Like most other arum plants, calla lilies contain toxins that lead to poisoning if swallowed. As it is a contact poison, even contact with the milky plant sap causes irritation to the skin and eyes. Therefore, always wear gloves when working with the plant and be sure to place it out of reach of overly curious pets and children.