Arum Lily Care Guide

One of the most beautiful and versatile bulb flowers, an Arum lily deserves a spot in any home or garden.

Arum lilies produce a stunning display of chalice-shaped flowers in the summer months, coupled with rich green foliage. Surprisingly, they’re very easy to grow and care for. 

What are Arum Lilies? 

Arum lilies are not true lilies. While similar, they originate in South Africa and instead belong to the Zantedeschia family.

Arum lilies produce funnel-shaped flowers that bring simple elegance to any indoor or outdoor space. Flowering in the summer, the traditional Arum lily is perfect for minimalist gardens. Those with white flowers are commonly used in wedding bouquets in South Africa. 

As well as their beautiful flowers, Arum lilies have large, glossy foliage that looks stunning grown next to ponds, in garden beds, or in large patio pots. 

Arum lilies can reach heights of around 1 m, with a spread spanning from 40 cm to 50 cm. They flower from early summer through to July, and are available in a multitude of colours. Some varieties have flecked or speckled leaves.

Arum Lily Varieties  

There’s a huge range of varieties of Arum lily. It’s recommended that you go for Arum lilies with a hardiness rating of H4, as these won’t need digging up for the winter. 

Arum lily: The mother species produces pure white flowers with a bright yellow spadix. H4 hardiness rating. 

Golden Chalice: Have a hardiness of H4 and speckled leaves. The spathe and spadix are a bright yellow. 

Flamingo: Have a warm yellow spadix surrounded by a pink spathe. 

Eyeliner: Produces dark crimson spathes with orange edging. 

Captain Palermo: Produces a stunning rich purple spathe and a yellow spadix, with white speckled leaves. 

Planting

Planting Rhizomes 

Arum lilies are very versatile, able to be grown in beds, borders or containers. They can be grown either outdoors or on a sunny windowsill. 

While growing from seed is possible, Arum lilies grown this way won’t flower until the third year. Most gardeners choose to grow from rhizomes instead.

Arum lily rhizomes are fairly easy to grow and don’t require a huge amount of attention. Provided they are planted properly and in the right location, you shouldn’t have many issues.

Rhizomes should be planted in pots indoors to become established, then moved outside in the early spring, once the danger of frost has passed.  

It’s important that the soil has been slightly warmed before the Arum lilies are planted outside.

Plant your rhizomes about 4” into the soil, spaced about a foot apart. Once planted, water thoroughly until shoots appear. 

They should be kept in a cool area but ideally in full sun. 

Planting from Full Growth

An Arum lily in full growth can be planted directly into your borders and beds, after the last frost or in the early summer before it gets too hot.

Before planting, dig organic matter like garden compost into the soil to improve the quality.

Position the plants at the same level as they were in the container, placing each one around a foot apart. Water thoroughly.  

Arum Lily Requirements 

Once planted, Arum lilies are fairly easy to manage. They need water and fertiliser, and many gardeners choose to mulch the areas surrounding them to prevent weeds from growing. 

Watering

Arum lilies that have flowered will require regular watering to maintain their growth. The soil should be kept moist but not soggy. Continue watering regularly until the end of the blooming season, but keep in mind that too much water can lead to fungal diseases.

During prolonged dry spells or heat waves, you should water more regularly. 

Sunlight 

Arum lilies prefer to be in a sunny spot of the garden, or in a room that gets a lot of light. 

However, it’s important they aren’t too hot. Don’t expose the plant to hours and hours of sun in very hot weather. Aim for bright, indirect light if you’re worried about your Arum lily getting too hot. 

Soil

Arum lilies aren’t particularly fussy when it comes to soil, but they do prefer moist, well-drained and good quality soil. Plant your Arum lilies after the last frost when the soil has warmed slightly. 

Temperature and Humidity

Arum lilies thrive in warm temperatures and humid climates. When the temperature drops in the late summer and early autumn, Arum lilies will go dormant. 

They also love humidity. If you’ve got an Arum lily houseplant, give it a spray of water a couple of times a week. 

Fertiliser 

While easy to care for, Arum lilies do require regular fertilisation during the growing season. It’s recommended that you use an all-purpose fertiliser once a month in the spring and summer months. 

Pruning

Arum lilies don’t require pruning, but they do need regular deadheading during the flowering season. 

Winter Protection

Once flowering has finished in late summer, you should continue watering and feeding Arum lilies for several weeks, until the leaves start to die back.

Whether you need to dig up the rhizomes will depend on your location as well as the hardiness rating. Those with an H4 rating can be left in the ground during the winter months. However, you should protect the rhizomes with a layer of mulch or horticultural fleece. 

Potted Arum lilies can be brought inside or kept in a greenhouse during the winter.

In very cold areas or with less hardy types of Arum lily, you’ll need to dig up the rhizomes. Shake off the soil then allow them to dry for a few days. Replant in containers and keep them above 10°C. Allow the leaves to die down and keep them in a dark spot. Don’t water them until they are replanted, which can be done in the spring once the soil has warmed. 

Rhizomes can be stored in a cool, dry and dark area until the temperature increases in the spring.

Common Issues 

There’s a couple of issues you may have with your arum lilies. 

Thrips are small, tubular flies that cause yellow and dark patches on the plant. Thrips scrape the cell membranes from the leaf, and need immediate treatment. 

Destroy as many bugs and larvae as possible using a damp cloth. Then gently wash the stems and leaves of your plant. Prune any parts of the plant that show signs of infestation and dispose of these parts. 

Treat your plant with insecticide or neem oil. 

Types of rot can result in poor growth and wilting. This includes crown rot, root rot and pythium rot, which commonly take hold in soil that doesn’t drain well. Soft rot can affect the rhizomes. 

To prevent this, ensure the Arum lilies are not overwatered and only plant them in well-drained soil. Remove weeds that are growing near the Arum lilies. 

When grown inside a greenhouse, Arum lilies may be susceptible to greenhouse pests including aphids, red spider mites and whiteflies. 

Arum Lily FAQ

Do arum lilies prefer sun or shade? 

Arum lilies are best grown in full sun or partial shade. They usually flower best in full sun, but you should ensure they don’t get too hot. 

If you are keeping your Arum lilies inside, ensure they are placed near a sunny window. 

How poisonous is an arum lily? 

All parts of the plant are poisonous and can lead to swelling of the tongue and throat if ingested. They are highly toxic to both dogs and cats, so pet owners should be very careful and consider another plant if they are worried. 

You should wear gloves when handling the plants and keep them away from children. 

What is the difference between a calla lily and an arum lily?

Calla lilies and Arum lilies are both variations of the Zantedeschia aethiopica. 

It’s common belief that these are the same plant, but actually there’s a couple of differences between them.

Arum lilies are hardier and have large, elegant white flowers. Calla lilies are smaller and tender, with flowers in a wide range of colours. 

Why is my arum lily dying? 

There’s a couple of reasons that your Arum lily may not be in peak health!

If the leaves are starting to droop, it could be that your watering schedule needs adjusting. Frustratingly, droopy leaves can be due to either over or underwatering! 

If the soil feels dry and the leaves are drooping, your lily may need water. If the soil feels very wet, don’t water it until it has dried. 

If the leaves are turning yellow, there’s likely a problem with the roots. A shortage of nutrients in the soil is often the case. Ensure the soil you have used is organic and high quality, and feed your Arum lily if you haven’t already. 

Yellow leaves can also be due to root rot, usually caused by overwatering. Ensure you only water your lily when the soil feels dry. 

Frost can affect the blooms and leaves of Arum lilies. If you have left your Arum lilies outside for the winter, cover them with mulch or horticultural fleece. 

If you enjoyed this article and want to learn more about how to keep your plants alive, check out our article on: Why Are My Plants Drooping & How To Fix It