Repotting guide

When & how to repot Arrow Arum (Peltandra virginica)

Also called Arrow Arum, Green Arrow Arum, Tuckahoe, Virginia Peltandra.

More about arrow arum

About Arrow Arum

Peltandra virginica · also called Arrow Arum, Green Arrow Arum · flowering

Peltandra virginica is a robust aquatic and emergent wetland perennial native to swamps, marshes, and slow-moving streams along the eastern coast of North America. It thrives in shallow standing water or permanently waterlogged boggy soil in full sun to part shade, producing distinctive glossy, arrow-shaped leaves up to 45 cm long and a green-spathed flower spike followed by green berry clusters. The single most important care fact is providing permanent wet feet — it must grow in consistently flooded or saturated soil. This plant is toxic to cats and dogs due to calcium oxalate crystals in all plant parts.

Mature size: 60–90 cm (2–3 ft) tall above water, spreading to 60–90 cm (2–3 ft) wide.

How to tell arrow arum needs repotting

Repotting on a calendar is less reliable than reading the plant. For arrow arum, 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 arrow arum) 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 arrow arum

Only every 2–4 years, when genuinely crowded. Arrow Arum 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. Clump-forming emergent aquatic perennial spreading by short rhizomes; forms expanding colonies in suitable wet conditions but is not aggressively invasive..

What size pot to step arrow arum up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Arrow Arum 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 arrow arum 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 arrow arum

Early spring, just as new growth restarts, is the ideal window for arrow arum. 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 arrow arum

Confirm it actually needs it. Slide arrow arum 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 arrow arum 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 heavy clay loam, pond mud, or aquatic compost, 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 arrow arum 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 arrow arum

Arrow Arum wants heavy clay loam, pond mud, or aquatic compost. Plant directly into pond silt or in baskets of heavy loam or specialist aquatic compost; avoid peat-based or free-draining mixes that dry out — root anchorage in firm substrate is important. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting arrow arum — frequently asked questions

How often should you repot arrow arum?

Only every 2–4 years, when genuinely crowded for arrow arum. Only repot arrow arum 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 heavy clay loam, pond mud, or aquatic compost. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does arrow arum need?

When is the best time of year to repot arrow arum?

Does arrow arum like to be root-bound?

Yes — arrow arum 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 arrow arum after repotting?

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