Wide-reaching leaves and blooms that last from early summer to mid-autumn make the calla lily (Zantedeschia aethiopica), wrongly called arum, one of the finest of the summer bulbs, and a South African native rather than an Ethiopian one. It asks for rich, well-drained soil that stays cool and moist — meet that and the flowering is spectacular.
| Name | Zantedeschia aethiopica |
|---|---|
| Family | Araceae |
| Type | bulbous perennial |
| Height | 20 to 40 inches (50 to 100 cm) |
| Exposure | full sun, part sun |
| Soil | rich, well drained |
| Flowering | early summer to mid-autumn |
From planting to pruning, every bit of attention goes towards helping the growth and bloom of your arum. Follow our advice to produce magnificent arums!
Arum bulbs are planted at the beginning of spring, around 1 ½ to 2 inches deep, from early spring to late spring.
Alternate your arums with other bulbs that bloom in summer.
Water sparingly at the beginning and then more regularly once flowers have appeared, until the end of the blooming season.
Arum grows very well adjoining a body of water, which indicates how much it needs water.
Like all bulbs that bloom in summer, water in case of prolonged dry spells or heat waves.
For spectacular blooming, add special bulb plant fertilizer.
Before changing a feeding schedule, identify why the leaves are yellowing: natural end-of-season dieback or overfeeding is a reason to stop fertilising, whereas a nutrient deficiency may instead call for corrective feeding.
Arum or calla lily is quite hardy even in cool winters. Typically, leaves will stay green until temperatures drop to 25°F (-4°C) for several nights in a row.
In areas that are prone to cold winters, protect the rhizomes with a thick layer of mulch. All airborne leaves may die off, but in spring they’ll grow back as lush and beautiful as ever! The mulch can either be a bed of dried leaves, hemp or flax straw, or ferns.
Tip: Before winter, dig out a portion of the rhizome and pot it in your house, and you’ll have arums in winter.
Once the leaves are completely yellow, you can cut them to the shortest.
You can also stow the bulb away without removing it from its pot, but the soil mix needs replacing every two years anyway.
How you see your arum through the cold months depends on where it grows. The four options described above line up like this.
| Situation | What to do | When | Point to watch |
|---|---|---|---|
| Planted in the ground, cold winter area | Cover the rhizomes with a thick layer of mulch: dried leaves, hemp or flax straw, or ferns | Before the first frost spells | Top growth may die off entirely, but regrows in spring |
| In a pot, bulb lifted | Cut leaves short, remove the bulb and clean the dirt off delicately, then store it | Once the leaves are completely yellow, until early spring | The spot must be cool, frost-free, very dry and dark |
| In a pot, bulb left in place | Stow the whole pot away without removing the bulb | Over winter, replanting interest resumes in early spring | The soil mix still needs replacing every two years |
| Brought indoors for winter flowers | Dig out a portion of the rhizome and pot it up for the house | Before winter | Gives you arums in bloom during the winter months |
Whichever route you take, wait until the leaves have yellowed completely before cutting anything back.
Check the undersides of the wide leaves for aphids and red spider mites, and dislodge them with a strong jet of water.
Among the named forms of Zantedeschia aethiopica, look for ‘Crowborough’ and ‘Green Goddess’, both suited to wet areas such as pond edges as well as to flower beds, edges or standalone spots, with stems worth cutting for a vase.
This bulb perennial is native to South Africa, not from Ethiopia as its scientific name shows.
Particularly exotic, it is perfectly suited to wet areas like water bodies and ponds, but is also the perfect plant for your flower beds, edges or standalone spots.
Even thought the spelling is arum, it is pronounced [uh-rome]!
Grown indoors rather than in the border, the plant pairs naturally with its cousin from the same family — see calla lily and anthurium indoors.
These flowers are pure marvels, before the blooming is over, cut a few stems off and place them in a beautiful vase!
