Repotting guide

When & how to repot Tongue Water Trumpet (Cryptocoryne lingua)

Also called Tongue Crypt, Tongue-Leaved Water Trumpet, Borneo Crypt.

More about tongue water trumpet

About Tongue Water Trumpet

Cryptocoryne lingua · also called Tongue Crypt, Tongue-Leaved Water Trumpet · tropical

Cryptocoryne lingua is a distinctive Bornean aquatic aroid with thick, tongue-shaped, leathery leaves adapted to tidal or brackish-influenced streams. It is among the most unusual Cryptocoryne species and is prized by specialist aquatic plant enthusiasts. Tolerates a wider range of water chemistry than most crypts. Toxic to pets as an aroid.

Mature size: 10–20 cm tall; leaves 8–15 cm long with a characteristically thick, paddle-like blade

Watch for — Algae growth on thick leaves: The leathery leaf surface can accumulate algae, particularly green spot algae. Introduce nerite snails or reduce light duration to control algae without harming the plant.

How to tell tongue water trumpet needs repotting

Repotting on a calendar is less reliable than reading the plant. For tongue water trumpet, 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 tongue water trumpet) 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 tongue water trumpet

Only every 2–4 years, when genuinely crowded. Tongue Water Trumpet 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. Compact rosette-forming aquatic perennial with distinctive thick, leathery tongue-shaped leaves.

What size pot to step tongue water trumpet up to

Go up only one pot size — roughly 2–3 cm (about an inch) wider in diameter, no more. Tongue Water Trumpet 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 tongue water trumpet 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 tongue water trumpet

Early spring, just as new growth restarts, is the ideal window for tongue water trumpet. 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 tongue water trumpet

Confirm it actually needs it. Slide tongue water trumpet 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 tongue water trumpet 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 fine aquatic substrate; tolerates a range from nutrient-poor to moderately rich, 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 tongue water trumpet 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 tongue water trumpet

Tongue Water Trumpet wants fine aquatic substrate; tolerates a range from nutrient-poor to moderately rich. Less demanding about substrate richness than other crypts. Fine gravel, aquatic sand, or a mixed aquatic substrate all work. Root tabs once or twice a year provide adequate nutrition. The thick rhizome anchors well even in fine substrates. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting tongue water trumpet — frequently asked questions

How often should you repot tongue water trumpet?

Only every 2–4 years, when genuinely crowded for tongue water trumpet. Only repot tongue water trumpet 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 fine aquatic substrate; tolerates a range from nutrient-poor to moderately rich. The key mistake is over-potting: a too-big pot stays wet and rots the roots.

What size pot does tongue water trumpet need?

When is the best time of year to repot tongue water trumpet?

Does tongue water trumpet like to be root-bound?

Yes — tongue water trumpet 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 tongue water trumpet after repotting?

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