Repotting guide

When & how to repot Calla Lily (Zantedeschia aethiopica)

Also called Calla lily, Arum lily, White arum lily, Lily of the Nile, Pig lily, Florist's calla, Trumpet lily.

More about calla lily

About Calla Lily

Zantedeschia aethiopica · also called Calla lily, Arum lily · flowering

The calla lily is a moisture-loving, rhizomatous perennial prized for sculptural white spathes on tall stems. Give it bright indirect light or part shade, consistently damp rich soil, and warmth of 60-80F. Despite the name it is not a true lily but an aroid, and the ASPCA lists it as toxic to dogs and cats.

Mature size: Typically 2-3 ft tall (up to about 3.25 ft / 1 m) and 1-2 ft wide, spreading slowly into clumps by rhizome.

Watch for — Failure to bloom: Usually from too little light, missing the winter dormancy/rest period, or over-feeding with high-nitrogen fertiliser. Provide bright light, a cool dormant rest, and a potassium-rich feed in season.

How to tell calla lily needs repotting

Repotting on a calendar is less reliable than reading the plant. For calla lily, watch for these signs:

Roots spiralling thickly out of the drainage holes or pushing the whole plant up out of the pot.
The pot is so packed that water runs straight through in seconds and barely wets the soil.
It has split a plastic pot, or the rootball is a solid mass with almost no soil left when you slide it out.
Growth and (for calla lily) flowering have clearly stalled despite good light and feeding — but remember this plant likes being snug, so a little crowding alone is not a reason to repot.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot calla lily

Only every 2–4 years, when genuinely crowded. Calla Lily is one of the plants that genuinely prefers a snug pot — it grows and flowers better with its roots a little restricted, so resist the urge to repot it on schedule. Clumping, rhizomatous herbaceous perennial forming a basal rosette of arrow-shaped, often glossy leaves, with flowers carried on tall stems above the foliage. Semi-evergreen in mild conditions but deciduous (dies back) in cold or dry spells, returning from the rhizome..

What size pot to step calla lily up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Calla Lily positively prefers a snug pot: it flowers and grows better when the roots are a little restricted. The single biggest repotting mistake here is over-potting — dropping calla lily into a pot two or three sizes up. All that surplus soil holds water the small root system cannot use, stays cold and wet, and rots the roots within weeks. When in doubt, choose the smaller pot.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot calla lily

Early spring, just as new growth restarts, is the ideal window for calla lily. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting calla lily

Confirm it actually needs it. Slide calla lily out and check the roots. Only continue if it is genuinely packed — this plant prefers a snug pot, so if there is still soil and room, put it straight back.
Pick a pot only one size up. Choose a pot just 2–3 cm wider with good drainage. Resist anything bigger; over-potting is the main killer here.
Ease it out gently. Water lightly the day before, then tip calla lily out, supporting the base. Tease the outer roots free only enough to stop them circling.
Repot at the same depth. Add a layer of fresh rich, humus-heavy, moisture-retentive mix, set the plant so the soil line sits exactly where it did before, and backfill around the sides, firming lightly.
Settle it in. Water once to settle the soil, then let it sit. Hold off on more water until the top of the soil dries — fresh soil around a small root system stays wet for a while.

Aftercare

Because the new soil holds more water than the old crammed rootball did, ease right back on watering — let the top of the soil dry before you water calla lily again, or you will rot the roots in the very pot you just moved it to. Keep it out of harsh direct sun for a fortnight. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for calla lily

Calla Lily wants rich, humus-heavy, moisture-retentive mix. Use a fertile, organically rich, moisture-retentive medium such as peat-free John Innes No.2 with added compost. Ideal pH is mildly acidic, roughly 5.5-6.5. Unlike most container plants it tolerates poorly drained, boggy conditions during growth. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting calla lily — frequently asked questions

How often should you repot calla lily?

Only every 2–4 years, when genuinely crowded for calla lily. Only repot calla lily every 2–4 years, and only when it is genuinely root-bound — it flowers and grows best slightly crowded. Step up just one pot size in spring using rich, humus-heavy, moisture-retentive mix. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does calla lily need?

When is the best time of year to repot calla lily?

Does calla lily like to be root-bound?

Yes — calla lily genuinely flowers and grows best when slightly pot-bound, so do not rush to repot it. The mistake to avoid is over-potting into a much larger pot: the excess soil stays wet, the roots cannot use it, and the plant rots. Only repot every few years and only one snug size up.

Should you fertilise calla lily after repotting?

Not immediately. Wait about 4 weeks after repotting calla lily. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.