Calla lily: growing tubers, care in a pot and how to overwinter it

The difference between the white arum lily and coloured hybrids, autumn clear-up and storing tubers, a spring start in a pot and care during the season.

In brief: Coloured calla lilies cannot stand temperatures below 5 °C. Start the tubers in March in a pot, put them outdoors after the last frosts, and in autumn, before the first frost, put them away for a dry rest without frost. The white arum lily wants moisture and overwinters in a cool bright room. Both are poisonous.

Latin name	Zantedeschia, Araceae
Starting the tubers	March–April in a pot indoors
Outdoors	after the last frosts, usually from mid May
Depth	in a pot the top of the tuber just below the surface, in a bed 5–8 cm
Flowering	coloured hybrids June–August
Overwintering hybrids	2–3 months dry, frost-free, ideally around 10 °C

The calla lily (Zantedeschia) is a plant with a funnel-shaped "flower" that is really a spathe wrapped around a spadix with tiny flowers. It is grown in a pot on a terrace, in a summer bed and as a houseplant, and cut stems last long in a vase.

Under one name, however, two groups of plants with entirely different care are sold. Anyone who confuses them usually loses the tubers during winter. That is why we begin with the distinction and right after it with what is current for calla lilies now in autumn.

White arum lily and coloured calla lilies: two different kinds of care

	White arum lily	Coloured calla lilies (hybrids)
Latin name	Zantedeschia aethiopica	hybrids of Z. elliottiana and Z. rehmannii
colour	white	yellow, orange, pink, burgundy, almost black
height	up to 90 cm	30–75 cm
water	plenty, tolerates even shallow water at a pond	less, needs good drainage
winter	in a container in a cool bright room, substrate slightly moist	complete rest, dry and dark, frost-free
when it flowers	depending on conditions, often late spring and summer	summer

In shops it is mainly the coloured hybrids that are sold as tubers. The white arum lily you more often buy as a finished plant in a pot.

What to do with a calla lily now in autumn

The end of September and October is a turning point for calla lilies. While spring bulbs are being planted in the ground now, as we describe in the article autumn planting of bulbs, summer calla lilies go the opposite way: from the garden into shelter. Coloured hybrids cannot tolerate temperatures below 5 °C, so with the first cold nights they must go under cover.

From September gradually reduce watering and stop feeding.
Before the first frost bring the pot into the house, or lift the tubers from the bed with their leaves.
Let the leaves die back. When they turn yellow, cut them off a little above the tuber.
Clean the tubers of soil and leave them to dry for a few days in an airy place.
Store them in a paper bag or box with dry peat or sawdust, in a dark frost-free place, ideally around 10 °C.
During winter check them once a month. Discard soft and mouldy ones.

Hybrids in a pot can overwinter right in the dry substrate; just store the pot in the cool and do not water it. Do not dry out the white arum lily. Move it to a bright room at around 10 °C and water only enough that the substrate does not dry out. Other summer tubers are overwintered similarly; an overview of temperatures can be found in the section on storage in the article bulbs and tuberous plants.

Starting the tubers in spring step by step

In March or April inspect the tubers. A healthy tuber is firm; small dry patches do not matter.
Choose a pot only slightly larger than the tuber. For one tuber a diameter of 15–20 cm is enough, for three 30 cm or more.
Fill it with a light, free-draining substrate. For coloured calla lilies mix in about a fifth of perlite.
Place the tuber with the buds upwards, that is the side with tiny bumps, and cover it so that the top is just below the surface.
Water sparingly and place in a bright warm spot. Until shoots grow, water only a little.
Harden the plants off gradually and put them outdoors once the frosts are over, usually from mid May. In a bed plant them 5–8 cm deep.

Position, watering and feeding during the season

Calla lilies flower best in sun, but also tolerate partial shade, especially in hot areas. Choose a sheltered spot, as wind breaks the tall stems. The white arum lily wants a permanently moist substrate; water coloured hybrids when the surface dries and do not let water stand in the saucer.

From the appearance of the leaves until the end of August feed every two weeks with a fertiliser for flowering or houseplants. Do not overdo the nitrogen, or the plant grows into leaves. Calla lilies combine well with other annuals in window boxes and large containers; you will find inspiration in the article about balcony plants that will flower until autumn.

Why a calla lily does not flower

The winter rest was missing. Coloured hybrids need 2–3 months dry. Without it they grow weakly.
Too much nitrogen or shade. The plant makes lush leaves and skips the flowers.
A small tuber. Small tubers or offsets flower only after a year or two.
A large pot. A calla lily in a too large container roots through first and flowers later.

Calla lily in a vase

Cut the stems or carefully pull them out at the base when the spathe is fully open. In a vase they last a long time, often more than a week. Pour only a few centimetres of water into the vase, as stems go soft in water. After handling cut calla lilies wash your hands, as the sap irritates.

Toxicity: children, dogs and cats

All calla lilies contain insoluble crystals of calcium oxalate. After chewing they cause burning and swelling in the mouth, on the tongue and lips, heavy drooling, vomiting and difficulty swallowing. The risk applies to children, dogs and cats. The sap can also irritate sensitive skin, so wear gloves when repotting and dividing tubers.

Place a pot with a calla lily out of reach of small children and animals. If a child has chewed a calla lily, contact the Toxicological Information Centre (224 919 293, 224 915 402). Take an animal to the vet.

Frequently asked questions

When should I plant calla lilies?

Start the tubers in March or April in a pot indoors. Move them outdoors only after the last frosts, usually from mid May. Plants bought in a pot can be planted out any time from May into summer.

How do I overwinter a calla lily?

Put coloured hybrids away before the first frost, let the leaves die back and store the tubers dry and dark without frost, ideally around 10 °C. Overwinter the white arum lily in a container in a cool bright room and do not let the substrate dry out.

Can a calla lily stay outdoors over winter?

Coloured hybrids cannot. Growing plants suffer already below 5 °C and frost destroys the tubers. The white arum lily is hardier and in mild areas of western Europe survives under a thick layer of mulch, but in the Czech Republic that is risky. It is safer to overwinter it in a container.

Is a calla lily poisonous to cats and dogs?

Yes. Crystals of calcium oxalate cause burning in the mouth, drooling and vomiting. If you suspect an animal has chewed the plant, contact a vet.

Why does my calla lily not flower?

Most often it lacked a winter rest, has too much nitrogen or shade, or the tuber is still small. Coloured hybrids need 2–3 months dry, then a sunny position and potassium feeding during growth.

Sources

Updated: 27 September 2026

Author: Jana Vránová, the editorial name of the Pěstík.cz team. She writes about the garden, herbs and essential oils. We take safety and dosage information from specialist literature and official sources, which we cite in every article.