Golden calla

Golden calla: how do you recognise it?

Habit

Upright clump about 60 cm tall and 30 cm wide.

Leaves

Arrow- to heart-shaped, glossy dark green with small, translucent white spots, on long stalks.

Flower

A trumpet-shaped, golden-yellow spathe up to 15 cm long around a yellow spike, on a sturdy stem above the leaves.

Tuber

A flattened, round tuber with the eyes on the upper side.

Sap

Contains needle-shaped crystals that irritate skin and mucous membranes.

Flowering: July–September · Plants: May–June

Why grow it?

• Bright golden-yellow flowers from July to September, a sunny eye-catcher in a pot or border.
• Handsome white-spotted leaves, attractive even when the plant is not in flower.
• An excellent cut flower that stays fresh in the vase for a long time.
• Ideal in a pot on the patio, easy to move and bring indoors for winter.
• Can also be grown as a houseplant in a bright spot.

Golden calla: where does it grow best?

• Sun to light partial shade; in full midday sun the soil dries out quickly.
• Humus-rich, free-draining soil: sand or loam, slightly acid to neutral.
• Moderately moist during growth and flowering, but never waterlogged.
• A warm spot sheltered from wind. In pots: one tuber per 20 cm pot or three in a 30 cm pot.
• In the border, plant 30 cm apart.

Light

Sun and partial shade

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

0.6 m tall, 0.3 m wide

Hardiness

Frost tender: lift the bulbs or tubers before the frost and store them frost-free

Goes well with

• African lily: Blue flower heads next to the yellow calla: a lovely contrast in large pots.
• Canna: Tropical-looking leaves and warm colours for the same sunny spot.
• Dahlia: Flowers at the same time in orange and red and is also lifted in autumn.
• Ornamental grasses: Fine, moving foliage as a calm backdrop for the sturdy flowers.

Golden calla: when and how to plant it?

Plant in May–June.

1. In April, start the tubers indoors in pots of compost at 15–20 °C in a bright place.
2. Plant the tuber 5–8 cm deep, eyes facing up.
3. Water sparingly at first, until the first leaf appears; then gradually give more.
4. Put the pot outside after mid-May or plant in the border in May–June, once there is no more risk of frost.
5. In the border, space plants 30 cm apart and water well after planting.
6. A compost mulch keeps the soil evenly moist.

Care

Water

Keep the soil evenly moist during growth and flowering, but not wet. Check pots regularly in summer.

Feeding

From June to August, a liquid fertiliser for flowering plants every two weeks.

Deadheading

Cut faded flower stems at the base so the plant produces new flowers.

Drying off

From late September, water less so the leaves turn yellow and the tuber goes dormant.

Cutting

Cut the flowers when the spathe is fully open and coloured; they last a long time in the vase.

Tip: After starting the tuber, only increase watering once the first leaf appears: this prevents rot. Three tubers together in a 30 cm pot give a fuller display.

Golden calla: when to prune it?

When: The golden calla is not pruned. You only remove faded flower stems and, in autumn, the dead leaves.

How:

• Cut faded flower stems at the base.
• Remove yellow or damaged leaves at the base.
• In autumn, cut the dead leaves back to just above the tuber before storing it.

Caution: Wear gloves when cutting leaves or stems: the sap can irritate the skin.

Pruning calendar and basic rules

Propagation

Division

When starting tubers in spring, detach small daughter tubers from the mother tuber, or cut a large tuber with a sharp knife into pieces with at least one eye each. Let the cuts dry for a day before potting.

Seed

Possible indoors or in a heated greenhouse, but slow: seedlings take several years to flower and may differ from the parent.

Golden calla: how does it get through the winter?

Hardy to 2 °C: protect in harsh winters.

• Not hardy: the tuber cannot take frost. Lift it in October, before the first night frost.
• Leave the tuber to dry for a few days in an airy, frost-free place, then remove soil and dead leaves.
• Store the tubers dry, dark and frost-free at 10–15 °C, in a box of dry sand or vermiculite.
• Pots can overwinter as they are, dry, in a frost-free cellar or garage.

Diseases and pests

• Tuber rot: Soft, foul-smelling tubers from starting or storing them too wet. Only increase watering once there are leaves, store dry and throw away rotten tubers.
• Aphids: On young leaves and flowers. Hose them off with water or let ladybirds do the work.
• Slugs: Outdoors they eat holes in young leaves. Pick them off in the evening and raise pots a little.
• No flowers: Too little light, a tuber that is too small or too much nitrogen. Give it a brighter spot and a fertiliser for flowering plants.
• Red spider mite: Indoors in dry air: fine yellow speckling and webbing on the leaves. Move the plant outside or raise the humidity.

Through the year

• January: Check stored tubers for rot.
• March: Check the tubers and set aside the firm ones.
• April: Start tubers in pots indoors at 15–20 °C. Water sparingly.
• May: Move outside after mid-May. Gradually increase watering.
• June: Plant in the border. Feed every two weeks.
• July: Flowering. Water and feed. Cut flowers.
• August: Flowering. Remove faded flower stems.
• September: Last flowers. Water less.
• October: Lift the tubers before the first frost and leave them to dry.
• November: Clean the tubers and store them dry and frost-free.

Edible and useful

Not edible. All parts of calla are poisonous: as with its close relative lords-and-ladies, the sap is full of needle-shaped crystals (calcium oxalate) which, when chewed, at once cause a burning pain and swelling of the lips, mouth and throat, with drooling and sometimes difficulty swallowing. Children, and cats and dogs that chew the leaves or flowers, are most at risk; if your cat or dog has chewed it and is drooling or its mouth is swelling, call your vet. Despite the name arum lily, calla is not a true lily: unlike lilies it does not cause kidney failure in cats, but still keep a vase of callas, or a calla in a pot indoors, out of their reach. The sap can irritate the skin: wear gloves when dividing the rhizome or tubers, and wash your hands afterwards. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• What looks like one large flower is a spathe around a spike carrying countless tiny flowers. It belongs to the arum family, like the lords-and-ladies of our woods.
• Many coloured callas on sale descend from crosses between this yellow species and the pink Zantedeschia rehmannii.
• The genus name honours the Italian physician and botanist Giovanni Zantedeschi.