Soil & potting mix
Best soil for Arum Lily (Zantedeschia aethiopica)
Also called Arum Lily, Calla Lily, White Calla, Pig Lily.
More about arum lily
About Arum Lily
Zantedeschia aethiopica · also called Arum Lily, Calla Lily · flowering
Zantedeschia aethiopica is a robust, rhizomatous perennial native to stream banks, marshes, and moist meadows in southern Africa, producing large, pure-white spathe flowers surrounding a yellow spadix from late winter to early summer. It thrives in moist to wet, humus-rich soil in full sun to part shade and can be grown as a marginal aquatic with roots in shallow water. In the UK it is hardy enough to overwinter outdoors in most areas with mulch protection; in colder climates (USDA zones below 8) lift rhizomes and store frost-free. All parts are toxic to cats and dogs.
Preferred mix: Moist, fertile loam or aquatic marginal compost
Watch for — Rhizome Rot: Overwatering in cool or waterlogged conditions during winter dormancy causes fungal rot of the rhizome; allow soil to dry slightly between waterings from autumn onward and ensure good drainage outside the growing season.
Why arum lily needs this mix
Arum Lily flowers hardest in a rich but free-draining loam — fed enough to fuel the display, open enough that the roots never waterlog.
- Flowering is expensive for arum lily: producing buds, blooms and seed draws heavily on nutrients and steady moisture, so the soil has to keep delivering all season.
- A loam-based mix holds nutrients and water far more evenly than a light peat mix, which means a longer, more reliable flowering period.
- It still needs sharp drainage — most flowering plants resent cold, wet feet far more than they resent being a little lean.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons arum lily struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- A thin, hungry or sandy mix gives arum lily weak growth and few, short-lived flowers — it simply runs out of fuel.
- A heavy, badly drained soil rots the roots or crown, often over a wet winter, and you lose the plant before it ever flowers again.
- Over-rich, high-nitrogen mixes can push lush leaf at the expense of flowers — balance, not excess, is the aim.
Either starving arum lily in a thin mix or drowning it in a heavy, badly drained one. It wants the rich-but-free-draining middle, plus a flowering (higher-potassium) feed in season.
pH — does it matter for arum lily?
Most flowering plants, including arum lily, do well around pH 6.0-7.0. A cheap soil test is worth it outdoors; one notable exception is any acid-lover (such as some hydrangeas), where pH directly changes flower colour.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
A quality bagged compost works for arum lily in pots if you add grit and a flowering feed. In beds, improving the existing soil with compost and ensuring drainage beats any bag.
Drainage and the pot
Free drainage protects the roots and especially the crown over winter — raised beds, grit in the planting hole and never a waterlogged spot. Containers must have a clear drainage hole.
For perennials, refresh the top layer and feed each spring rather than disturbing the roots; for container displays, start with fresh rich mix each season. When the time comes, our repotting guide for arum lily covers the timing and technique step by step.
Arum Lily soil — frequently asked questions
What is the best soil mix for arum lily?
3 parts good loam or quality peat-free compost : 1 part well-rotted compost or leaf mould : 1 part grit or perlite. Flowering is expensive for arum lily: producing buds, blooms and seed draws heavily on nutrients and steady moisture, so the soil has to keep delivering all season.
Can I use normal potting soil for arum lily?
A thin, hungry or sandy mix gives arum lily weak growth and few, short-lived flowers — it simply runs out of fuel. A quality bagged compost works for arum lily in pots if you add grit and a flowering feed. In beds, improving the existing soil with compost and ensuring drainage beats any bag.
Does arum lily need a special pH?
Most flowering plants, including arum lily, do well around pH 6.0-7.0. A cheap soil test is worth it outdoors; one notable exception is any acid-lover (such as some hydrangeas), where pH directly changes flower colour.
Should I buy a bagged mix or make my own for arum lily?
A quality bagged compost works for arum lily in pots if you add grit and a flowering feed. In beds, improving the existing soil with compost and ensuring drainage beats any bag.
How often should I refresh the soil for arum lily?
For perennials, refresh the top layer and feed each spring rather than disturbing the roots; for container displays, start with fresh rich mix each season. Free drainage protects the roots and especially the crown over winter — raised beds, grit in the planting hole and never a waterlogged spot. Containers must have a clear drainage hole.
Keep reading
- Arum Lily care — the full brief (light, water, humidity, problems, pet safety)
- How often to water arum lily — the schedule the mix feeds into
- Repotting arum lily — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Should I water my plant? The simple check first
- Why is my plant wilting? Wet vs dry diagnosis
- Root rot — how the wrong soil starts it, and how to save the plant
- Best soil for western bog laurel
- Best soil for scarlet leucothoe
- Best soil for coastal leucothoe
- All 10153 soil and potting-mix guides in the Growli library