Repotting guide

When & how to repot Zantedeschia 'Edge of Night' (Zantedeschia 'Edge of Night')

Also called Edge of Night calla lily, deep purple calla.

More about zantedeschia 'edge of night'

About Zantedeschia 'Edge of Night'

Zantedeschia 'Edge of Night' · also called Edge of Night calla lily, deep purple calla · flowering

Zantedeschia 'Edge of Night' is a hybrid calla lily prized for near-black, velvety purple flowers above glossy spotted foliage. A tender tuberous perennial, it loves warmth, bright light and moist, fertile, well-drained soil. Lift the rhizome before frost in cold climates and store dry. Striking in containers and summer borders, it reaches around 50-60 cm.

Mature size: Around 50-60 cm tall with a 30-40 cm spread.

Watch for — Rhizome rot: Cold, wet, poorly drained soil rots the rhizome quickly. Plant in free-draining mix, avoid overwatering, and never leave tubers in waterlogged pots over winter.

How to tell zantedeschia 'edge of night' needs repotting

Repotting on a calendar is less reliable than reading the plant. For zantedeschia 'edge of night', 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 zantedeschia 'edge of night') 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 zantedeschia 'edge of night'

Only every 2–4 years, when genuinely crowded. Zantedeschia 'Edge of Night' 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. Tender rhizomatous perennial forming a clump of upright arrow-shaped leaves with funnel-shaped spathes held on slender stems; dies back to the rhizome in winter..

What size pot to step zantedeschia 'edge of night' up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Zantedeschia 'Edge of Night' 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 zantedeschia 'edge of night' 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 zantedeschia 'edge of night'

Early spring, just as new growth restarts, is the ideal window for zantedeschia 'edge of night'. 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 zantedeschia 'edge of night'

Confirm it actually needs it. Slide zantedeschia 'edge of night' 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 zantedeschia 'edge of night' 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, free-draining, moisture-retentive loam or quality potting 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 zantedeschia 'edge of night' 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 zantedeschia 'edge of night'

Zantedeschia 'Edge of Night' wants rich, free-draining, moisture-retentive loam or quality potting mix. Use a fertile mix with added compost and grit or perlite for drainage. Plant rhizomes 5-10 cm deep, eyes upward. Slightly acidic to neutral pH suits them; avoid heavy, waterlogged ground. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting zantedeschia 'edge of night' — frequently asked questions

How often should you repot zantedeschia 'edge of night'?

Only every 2–4 years, when genuinely crowded for zantedeschia 'edge of night'. Only repot zantedeschia 'edge of night' 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, free-draining, moisture-retentive loam or quality potting mix. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does zantedeschia 'edge of night' need?

When is the best time of year to repot zantedeschia 'edge of night'?

Does zantedeschia 'edge of night' like to be root-bound?

Yes — zantedeschia 'edge of night' 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 zantedeschia 'edge of night' after repotting?

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