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Calling all Calla Lilies!


By Graham Clarke

The last quarter of a century has seen an explosion in the breeding of calla lilies – tender forms of Zantedeschia. Like most gardeners over the age of 30, the first zantedeschia I ever encountered was the hardy arum lily, Z. aethiopica. It’s a beautiful, lush, white-flowered perennial that likes to have its roots in moist soil. There are several forms of it, with varying amounts of green and pink in the flowers, and with plants in varying degrees of hardiness. But essentially they are all the same.

Flowering Callas in the field

However, over the last 25 years or so more tender forms have been created, mainly hybrids and cultivars of Z. elliotiana and Z. rehmannii. Referred to as calla lilies, they typically have lush green leaves with white spots, and pretty flowers in cream, yellow, orange, pink or dark purple.

These tender varieties can be displayed either as houseplants, or planted outside for the summer in containers or as seasonal outdoor bedding displays. They all flower in summer.

Floral artists ❤ Calla Lilies

The large, striking, blade-shaped blooms (called ‘spathes’) are very popular with floral artists, and each year breeders across the world – but particularly in the Netherlands and New Zealand – bring out new hybrids with ever more vividly coloured flowers. This means gardeners have an unprecedented range of varieties to choose from, while the current trend for tropical-looking planting has made the large, architectural leaves and lush growth habit of calla lilies popular in modern gardens.

Cut calla lilies

Callas in the vase

Farmer Gracy's Calla Lily Conundrum
See if you can work out the answer to this question (answer at the bottom of this page).
The calla lily (zantedeschia) was first brought to the UK from its native South Africa by a plant hunter in the 18th century. Who?
1) David Douglas
2) Francis Masson
3) Ernest Wilson
4) John Veitch?

Order calla lily bulbs (actually rhizomes) now, and plant them in pots for growing on before putting them out in the garden. Pot them up any time from March to the end of May, and you will have luxuriant, highly-coloured flowering plants by summer. You can even have early flowering plants by Easter-time, but the rhizomes will need to have been planted around Christmas-time.

Planting Calla Lilies in pots

Once planted into pots, keep them in a light, cool place with a night temperature of 16°C, and a slightly warmer day temperature. Feed every two weeks with a high-nitrogen fertiliser when in active growth, but don’t feed when the plants are in flower.

Planting Calla Lily bulbs in container

A high-potash fertiliser, such as a tomato feed, can be given once a week after flowers have stopped appearing.

Growing Calla Lilies in the Garden Soil

By late spring, after the last frosts have occurred, the calla lilies will have developed into nice little potted plants, and are ready to go outside. If you want to plant them in the garden soil, put them where they can be in full sun for most of the day. Some late afternoon shade is welcome, particularly in a hot summer. Your calla lilies will perform best in a moist, well-drained fertile soil that has been enriched with compost.

Calla Lily Bulbs

Prepare your planting hole by mixing in some well-rotted compost and a little bone meal. Plant the tubers horizontally, 5cm deep and 30cm apart, with the eyes facing upwards. After planting, water the soil generously, soaking it.

Growing Calla Lilies in Containers

Calla lilies are very successful when grown in patio pots and containers. Use a loam-based compost, such as John Innes No. 2, and plant the rhizomes (with the eyes or ‘buds’ of the rhizome uppermost) just showing at the compost surface. Water freely through the summer, and feed as described above.

Calla Bulbs in containers

Calla Bulbs in a basket

Growing Calla Lilies as Indoor Plants

When they are grown in small pots for keeping indoors, the compost should be kept consistently moist, and plants should be given a weak solution of liquid plant food every three weeks while they are in growth.

The best place to site them is in a west-facing window, where the air temperature does not rise much above 21°C. A south-facing window may be too hot when the sun is at its strongest in summer. Remove the flowers when they start to fade. When the plant has finished blooming, allow the leaves to turn brown, and reduce watering. Stop watering completely once all the foliage has died back.

Callas indoors

The rhizomes should now be allowed to rest for two or three months, still in the same pot. Don’t give them any water. After this period, they can be removed from the compost, cleaned off, and then repotted in fresh soil. The process can then start all over again.

Calla Lilies at the End of the Season

If you plant your calla lilies in the ground, to decorate summer flowerbeds, you will need to lift the rhizomes before the first frosts. Clean off excess soil, let them dry out of the direct sun for a few days, and store them over winter before replanting them next spring when the risk of frost is over.

Store the rhizomes in trays of compost in a cool, dark, frost-free place such as a shed or garage. Alternatively, overwinter indoors or in a warm greenhouse or conservatory, but the temperature should not really exceed 10°C, as the rhizome could dry out. Moisture levels are important over the winter period. Dampen the rhizomes occasionally, but not too much, and remember that the cooler the temperature, the less moisture will be required.

Calla rhizomes

Calla lilies can, as we have seen, suffer from cold damage, but otherwise they are no more trouble than the majority of outdoor and indoor plants. Outside they can be prone to slugs and snails, but otherwise they are fairly trouble-free. If kept under cover in a greenhouse or conservatory they may suffer (like the majority of indoor plants) attacks from aphids, red spider mite or whitefly.

Calla Lily Varieties

There are several dozen varieties available commercially, all with slightly different colouring to the flowers, or patterning to the leaves. Farmer Gracy has selected 23 of the finest varieties, but these four are my absolute favourites:

Calla Lily Mango UK

  • Calla Lily Mango
    Beautiful white spotted foliage from late spring; when grown in pots and overwintered indoors, it produces burnt-orange spathes from June onwards.

Calla Lily Picasso UK

  • Calla Lily Picasso
    The leaves have twisted edges and are generously spotted with white; bicoloured spathes comprising deep purple throats and creamy white margins are carried over summer.

Calla Lily Schwarzwalder UK

  • Calla Lily Schwarzwalder
    The name translates as ‘Black forest’ and you can see why…the flowers are a deep cherry red with a black interior; sometime they are nearly all-black, but edged with red. The leaves are lightly spotted with light green.

 Calla Lily Akela UK

  • Calla Lily Akela
    Dark purple flowers and delicate white spotted foliage; this is one of the most dramatic of varieties, and a large grouping of this variety in a garden bed will be a talking point with friends and family for years!

The answer to the Calla Lily Conundrum: 2) Francis Masson, born in Aberdeen, Scotland in 1741. In the 1760s, he went to work at Kew Gardens as an under-gardener, and was sent abroad to hunt new plants. He sailed with James Cook on HMS Resolution to South Africa, landing in October 1772. Masson stayed there for three years, during which time he sent back to England more than 500 species of plant – including Agapanthus (African lily), Strelitzia (bird of paradise flower), Amaryllis belladonna (the Belladonna lily) and Zantedeschia (the arum lily).


"Calling all Calla Lilies!"
is a guest blog written by:

Graham Clarke
Horticultural & Publishing
Consultant
at HHPS Ltd


1 comment


  • Susan Williams

    Wonderful looking Calla Lily ,So many lovely colours it is hard to choose which ones to buy,


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