Horticulture Magazine

Zantedeschia Aethiopica ‘Arum Lily’ Plant Care & Growing Tips

beautiful white Zantedeschia flowers on a green background

Arum Lily Overview

Official Plant NameZantedeschia Aethiopica
Common Name(s)Arum Lily
Plant TypePerennial
Native AreaSouth Africa / Lesotho
Hardiness RatingH4
ToxicityToxic if ingested
FoliageHerbaceous or semi-evergreen
FlowersWhite, funnel-shaped flowers
When To Sow / Plant OutMarch, April, May
Flowering MonthsJune, July, August
Sunlight

Preferred
Full Sun or Partial Shade

Exposure
Sheltered

Size

Height
0.5 – 1M

Spread
0.1 – 0.5M

Bloom Time
May – August

Soil

Preferred
Clay, loam

Moisture
Poorly drained

pH
Any

The Arum Lily produces a ‘flower’ that is simple yet chic, looking for all the world like a designer-sculpted piece in minimalist style.

One attribute that is definitely not minimalist is the amazingly wide range of brilliant ‘popping’ colours the ‘flower’ comes in.

Not a true flower, the form comprises a one-sheet ‘scarf’ – the bract – wrapped around a bright spike – the inflorescence.

Isn’t the Arum Lily a ‘Lily’?

Whoever has seen an Arum Lily knows that it is not a ‘regular’ flower. It comprises of a prominent central protuberance – perhaps the flower’s style? – wrapped around by a single long ‘petal’ as if it were a scarf.

They come in somewhat different dimensions and ‘designs,’ and in quite a range of colour tones.

In fact, that protuberance is a spadix – a spike that is actually an inflorescence of tiny florets. And that long, wrap-around ‘petal’ is the spathe which is a type of bract – a special raised leaf that is typically coloured and shields one or more flowers.

What is called ‘Arum Lily’ is not really a lily at all.

It is not even a member of the Lily family – Liliaceae – let alone the Lily genus – Lilium.

The Arum Lily is a member of Genus Zantedeschia within Family Araceae. Various species of the Zantedeschia genus are often interchangeably called ‘Arum Lily’ and ‘Calla Lily,’ especially in North America.

We refer only to species Zantedeschia aethiopica and its cultivars as ‘Arum Lily;’ conversely and equivalently, we consider the common name ‘Arum Lily’ to apply only to Zantedeschia aethiopica and its cultivars.

The species bears a ‘flower’ that has a pure white spathe encircling a sunny yellow spadix.

Cultivars produce ‘flowers’ with spadices in colours ranging from creamy white through pale orange to deep purple and even glazed black, and spathes in hues ranging from white and pastel pink to deep purple and grey-purple to blackish hues.

These ‘flowers’ are 20 to 25 centimetres around. 

classic white coloured arum lilies
Arum Lily ‘Classic’ – The Zantedeschia Aethiopica Species Flower

Properties of Arum Lily

All species of Genus Zantedeschia produce this floral form comprising of spadix and spathe.

This is a defining characteristic of members of the Arum Family to which Zantedeschia belongs, and the fact of the spadix being a dense inflorescence of florets and the spathe being a shielding bract is very obvious in one or two generas’ ‘flowers,’ for example, Xanthosoma.

Diametrically opposite to these are Zantedeschia aethiopica or Arum Lily and its cultivars, looking for all the world like stylised floral forms sculpted by a Twentieth Century artist.

Arum Lily is a herbaceous perennial though it may be deciduous, semi-evergreen, or evergreen depending on a given region’s climate.

It is evergreen in sub-tropical climates when it gets year-round water and is deciduous in temperate regions, but which have relatively mild winters that it can weather. 

These rhizomatous plants lack a central stem as the stalks and petioles emerge directly from the rhizomes.

The leaves are sagittate or arrowhead-shaped and are typically 35 to 40 centimetres long, glossy and of a rich green hue. Some cultivars’ foliage is flecked or liberally speckled with white.

This exotic plant is not only a stylish, unusually chic one, when planted in optimal conditions it will turn out to be very low maintenance.

The flower not only looks lovely in a vase indoors, it is also long-lasting as a cut flower.

various cultivar of arum lilies in different colours
Arum Lily in Gorgeous Technicolour – Various Cultivars’ Flowers

Background and Origins

Zantedeschia aethiopica is native to the south-eastern region of South Africa. It has been naturalised in quite a disparate patchwork of regions and countries on all continents (except Antarctica) including the United Kingdom.   

This species and others of the same genus arrived on European shores during the 1660s.

The genus name is a tip of the hat to Giovanni Zantedeschi, an Italian botanist who made pioneering discoveries over the Eighteen and Nineteenth Centuries.

This plant is prized in its native country of South Africa where it graces many gardens, and where the flowers have also graced innumerable bridal bouquets. 

Varieties

Arum Lily and its various cultivars reach heights of 60 centimetres to about one metre. Their spreads are typically within a narrow range of 40 to 50 centimetres. 

In the Northern Hemisphere, they flower from June through July but sometimes start as early as May.

The different cultivars vary in the colours of their ‘flowers’ but some also have flecked or speckled leaves, and a few top out at 60 centimetres while some can grow taller. We present a Top Twenty list below.

Z. aethiopica or Arum Lily, is the ‘mother species.’ As mentioned in the introduction, the spathe is pure white and the spadix is a cheery yellow. Hardy to H4. 

Z. ‘Crowborough’ has ‘flowers’ that are the same colours as the species but the spathes are just a bit smaller, are wavy, somewhat furled, and display a pleasingly irregular appearance. Hardy to H4. RHS Award of Garden Merit.

Z. ‘Crystal Clear’ is not infrequently entirely pure white. Pure white spathes encircle spadices that may be creamy yellow, off-white, or white. Hardy to H4. 

Z. ‘Mint Julip’ have yellow spadices with spathes in shades of creamy white to a rich cream. Hardiness rating of H1C.

Z. ‘Golden Chalice’ have spadices and spathes in matching colour, this being a bright, buttery yellow. The leaves are heavily speckled. Hardy to H4.

white arum lilies used in a bridal bouquet
White Arum Lilies are Obligatory in Bridal Bouquets in South Africa

Z. ‘Flamingo’, one of the most delicate varieties, has rich, warm yellow spadices encircled by spathes that range from pink-suffused white to pale pastel pink. Hardy to H4.

Z. ‘Crystal Blush’ has a yellow spadix which is smaller and less prominent than most. The spathe is a delightful blush pink for the most part but can be gradated from pinkish-white through candy pink. Hardiness rating of H1C.

Z. ‘Eyeliner’ has a dark, brownish-yellow spadix and a spathe of a rich crimson-maroon verging on black with orange edging. Hardiness rating of H1C.

Z. ‘Captain Palermo’ is perhaps the winner in the Captain Series of Arum Lilies and must be considered a top contender for best Arum Lily variety. It has the customary yellow spadix encircled by a spathe that ranges from a delicious rich purple to a smoky blackish maroon-violet, making it unquestionably a superlative choice for an accent plant. It has white-speckled leaves. Hardiness rating of H1C.

Z. ‘Cantor’ gives heavy competition to ‘Captain Palermo’ as a top pick for best specimen Arum Lily. It has a purple spadix encircled by a spathe that is gradated from purple near the lips down to near-black at the base and into the throat, or it may be a riveting violet hue. It has liberally and heavily speckled leaves. Hardiness rating of H1C.

Z. ‘Captain Chelsea’ has a yellow spadix with a multicoloured spathe. On the outside it is flushed with light maroon on a yellow ground while on the inside it has a thick border of bright yellow and is maroon in the throat, with a progressively darker hue. Hardiness rating of H1C

Z. ‘Captain Romance’ features a deep yellow to yellowish-orange spadix encircled with a candy pink spathe that is flushed greenish-yellow near the base. Hardiness rating of H1C.

Pink coloured Arum Lily ‘Captain Romance’ in an outdoor setting
Ideal for a Valentine’s Day Bouquet – Arum Lily ‘Captain Romance’

Z. ‘Captain Safari’ has a yellow spadix and a spathe that is predominantly rose pink but flushed with yellow and deeper pink. Hardiness rating of H1C.

Z. ‘Mozart’ has an unusual orange spadix; also unusual is the spathe. It is multicoloured and gradated, wearing flushes of colour in yellow, pink, and peach; these colours may occur anywhere on the spathe. The leaves have some white flecks. Hardy to H4.

Z. ‘Bingo’ have yellow spadices wrapped around by spathes of a rich purple-pink gradating to yellowish-cream at the base. Leaves are liberally speckled with white. Hardiness rating of H1C.

Z. ‘Fire Glow’ have orangeish spadices encircled by spathes in a gorgeous hue of vermilion-to-red, flushed along the sides and in the throat with bright yellow. Leaves are speckled with white. Hardy to H4.

Z. ‘Odessa’ flowers have very short spadices that are barely visible. The spathe is an amazing hue of near black maroon-violet. The striking flower makes this cultivar an outstanding choice for a specimen plant. On top of that, the leaves have small white flecks. Hardiness rating of H1C.

Z. ‘Picasso’ has yellow spadices encircled in a bi-coloured spathe that have broad white borders and are light purple with the hue getting progressively deeper nearer the base and deeper in the throat. Hardiness rating of H1C.

Z. ‘Green Goddess’ is a very popular cultivar but a green ‘flower’ may not be to everyone’s taste. While the spadix is the default yellow, the spathes – which are bracts, of course – are green with white throats. Hardy to H4. RHS Award of Garden Merit.

Z. ‘White Giant’, as the name indicates, is an outlier. It attains a height of 2 metres and the foliage too is different as the leaves are liberally speckled with white. White spathes encircle yellow spadices. Hardy to H4.

Arum ‘White Giant’ with white speckled leaves
A Stand of Robust Arum Lily ‘White Giant’ – Notice the Liberally Speckled Leaves

Habitat and Growing Conditions

Zantedeschia aethiopica inhabits all types of damp low-lying ground.

It grows in fields and meadows by waterways and ponds, and even in swamps and marshes in its native habitat in (some provinces of) South Africa.

In the wild it is not found in dry ground or in the highlands.

Zantedeschia aethiopica itself and some cultivars are hardy to H4 which means that they are ‘just enough’ hardy in the United Kingdom and are best protected during the winter while most cultivars are hardy only to H1C – basically, not hardy at all. 

Where to Plant Arum Lily

If you live in a region that does not suffer from frost or frigid winters, you can plant the species and those cultivars that are hardy to H4 in beds and, ideally, near ponds and any other waterways where these plants will thrive in the moist soil, though they would need winter protection.

Because of its habitat preferences, this plant is a natural choice for water gardens; and because of its ‘flower’ it is a great choice for contemporary gardens and modernist, minimal-style gardens.

The unusual ‘flower’ makes Arum Lily a top choice as a specimen plant to be grown in containers set by the doorway or on a parapet, some cultivars being more suited to such display than others.

If you grow the tender cultivars in containers you will not only get an accent plant with a most unusual flower, it will be very convenient to overwinter indoors or in a greenhouse.

Though Arum Lilies’ water needs are high, their sunlight needs are low, so they can make very attractive year-round houseplants.

elliptical white Zantedeschia aethiopica flowers
That Does Look Like a Designer-Sculpted Flower, Doesn’t It?

Feeding, Care and Growing Tips

Although Arum Lilies can be grown from seed, the plants will not bloom until the third year so they are most commonly grown from rhizomes. Also, seeds require a consistent temperature within a very narrow range to germinate.

Avoid growing cultivars with a hardiness rating of H1C in the ground, otherwise you will have to remove the rhizomes every fall and store them indoors, making sure that they are kept damp.

If you grow the H4 varieties outdoors then, in more regions of the United Kingdom than not, you will be able to allow them to stay in the ground through the winter; simply protect the rhizomes with horticultural fleece or a layer of leaf mulch.

In most regions of the United Kingdom, sites with dappled sunlight will prove best through full sun or morning sun will also do nicely. A sheltered location facing south through west is preferable.

Soil should be of a rich and fertile type incorporating organic content, such as well-rotted manure or humus, in a loam that contains clay, silt, and sand.

If your soil is lacking in clay or manure then amend it with vermiculite for water retention.

Zantedeschia 'Captain Safari' with purple and red flowers
Brilliant-Hued Arum Lilies Including ‘Captain Safari’

Rhizomes of the H4 cultivars may be planted outdoors after the last frost has well passed. They should be planted about 10 centimetres deep such that their eyes just ‘peek’ out of the soil’s surface.

Space them about 40 centimetres apart. Rhizomes of any and all hardiness ratings may also be planted in containers.

Arum Lilies, especially during the growing season, should be watered well. Ensure that the soil is consistently moist.

Just before the start of flowering season, Arum Lily may be fertilised with a slow-release organic fertiliser with a balance of approximately 5-10-10. Otherwise fertilise it with a ‘regular release’ fertiliser, applied in moderation, every two to three weeks. 

As mentioned above, the semi-hardy varieties’ rhizomes may be kept outdoors if they are protected by leaf mulch or a layer of fleece.

Arum Lilies growing in pots may be brought indoors (or kept in a greenhouse) before winter.

They can grace a room in your home in a spot where they get a few hours of sunlight or several hours of indirect light.

If outdoor plants have not dropped their leaves in winter, cover them with a lightweight horticultural fleece.

Arum Lily ‘Mozart’ with peach and red shading
Arum Lily ‘Mozart’ Displays Lovely Gradations of Yellow, Pink and Peach

Pruning Arum Lily

Arum Lilies do not need to be pruned. You may trim overgrown plants if they look unkempt.

Any leaves that winter frost has blackened should be cut off.

Common Diseases and Problems

Arum Lilies are quite vigorous plants. On occasion they may succumb to aphids and sometimes to thrips. 

Thrips are the more troublesome pests. Any parts of a plant that show signs of a thrip infestation should be pruned and disposed off.

Thrips can be treated with a combination of insecticidal soap, (diluted) Neem Oil and beneficial predators like ladybugs.

Odessa Arum with a deep purple colour
The Arum Lily ‘Odessa’ Bloom – Isn’t that an Amazing Hue?

Arum Lily is Poisonous

Though certainly no hemlock or foxglove, Arum Lily is still toxic and, therefore, calls for due precautions in households with small children, cats and dogs.

The toxic compounds present in the plant are calcium oxalate and other oxalates.

Symptoms include drooling with an inability to swallow. Mouth, tongue and lips are affected by a burning sensation, and these may be visibly inflamed.

If a child or pet is suspected to be suffering from Arum Lily poisoning, administer water or other fluids, and promptly take him/her to a doctor.

Where to Buy Arum Lily

The species and a few cultivars, for example ‘Green Goddess’ and ‘Crowborough’, are so widely available that you should be able to get them at just about any nursery.

Other cultivars can be located at speciality online merchants.

arum lily 'picasso' in purple white and yellow
Arum Lily ‘Picasso’ has Complementary Colours: Purple and Yellow

As long as each part of a rhizome that is cut into two has an eye (or bud), it will give rise to a new plant. 

You can get new plants simply by dividing clumps in the spring. 

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