Repotting guide

When & how to repot kidney-leaved bladderwort (Utricularia reniformis)

Also called kidney-leaved bladderwort, giant bladderwort.

More about kidney-leaved bladderwort

About kidney-leaved bladderwort

Utricularia reniformis · also called kidney-leaved bladderwort, giant bladderwort · houseplant

One of the most striking bladderworts, Utricularia reniformis is a large epiphytic to terrestrial carnivore from the coastal mountains of southern Brazil. It produces dramatic kidney-shaped leaves up to 7 cm wide and imposing lilac flower scapes reaching 60 cm tall. It thrives in cool-to-intermediate humidity-rich terrarium or greenhouse conditions.

Mature size: Leaves 5–10 cm (2–4 in) wide; flower scapes 30–60 cm (12–24 in) tall

Watch for — Leaf wilt and dieback in low humidity: The large fleshy leaves desiccate rapidly below 50% relative humidity. Yellowing, wilting, and leaf drop follow. Move to a closed or semi-closed terrarium immediately. The plant will recover from rhizomes even if all leaves are lost provided the root zone stays moist.

How to tell kidney-leaved bladderwort needs repotting

Repotting on a calendar is less reliable than reading the plant. For kidney-leaved bladderwort, watch for these signs:

Roots poking out of the drainage holes or coiling visibly around the inside of the pot.
You are watering far more often than you used to because the rootball dries out within a day or two.
Water runs straight through and out the bottom without soaking in.
Top growth has slowed or new kidney-leaved bladderwort leaves are noticeably smaller than older ones despite good light.

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 kidney-leaved bladderwort

Every 12–18 months — sooner if roots show fast. kidney-leaved bladderwort's growth habit — terrestrial to epiphytic perennial with large, fleshy kidney-shaped leaves on petioles; produces an extensive underground network of stolons bearing bladder traps, with tall upright racemes bearing 2–5 large lilac flowers. — sets the pace. One of the most striking bladderworts, Utricularia reniformis is a large epiphytic to terrestrial carnivore from the coastal mountains of southern Brazil. It produces dramatic kidney-shaped leaves up to 7 cm wide and imposing lilac flower scapes reaching 60 cm tall. It thrives in cool-to-intermediate humidity-rich terrarium or greenhouse conditions.

What size pot to step kidney-leaved bladderwort up to

Step up one pot size — about 2–3 cm (an inch) wider. kidney-leaved bladderwort grows fast, so it will fill that space within a season, but jumping several sizes at once still backfires: the unused soil stays soggy and rots even a vigorous root system. One size at a time, every year or so, is the rhythm.

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 kidney-leaved bladderwort

Early spring, just as new growth restarts, is the ideal window for kidney-leaved bladderwort. 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 kidney-leaved bladderwort

Time it for spring. Repot kidney-leaved bladderwort in early spring as growth restarts so it re-roots quickly into the fresh soil.
Choose one size up. Pick a pot about 2–3 cm wider with drainage holes. One step only — a much bigger pot stays soggy and rots roots.
Ease the plant out. Water lightly the day before, then tip kidney-leaved bladderwort out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh live or long-fibre sphagnum moss in the new pot, set the plant so its soil line is unchanged, and backfill, firming lightly.
Water and pause feeding. Water once to settle the soil. Hold off fertiliser for about a month — fresh mix already has nutrients and feeding now burns new roots.

Aftercare

Water kidney-leaved bladderwort once to settle the soil, then let the surface dry before watering again — fresh mix around the roots stays wetter than the old compacted ball, so the commonest post-repot mistake is overwatering. Keep it out of direct sun for a week or two while roots re-establish. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for kidney-leaved bladderwort

kidney-leaved bladderwort wants live or long-fibre sphagnum moss. Best grown in pure live or dried long-fibre sphagnum moss, which mimics its epiphytic habitat and retains the right moisture balance. Alternatively use a mix of two parts sphagnum to one part perlite. Avoid peat-based mixes that compact and exclude oxygen. Wide, shallow pots or wooden slat baskets allow rhizomes to spread freely. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting kidney-leaved bladderwort — frequently asked questions

How often should you repot kidney-leaved bladderwort?

Every 12–18 months — sooner if roots show fast for kidney-leaved bladderwort. Repot kidney-leaved bladderwort roughly every 12–18 months, in early spring as growth restarts. It grows fast and circles its pot quickly, so step up one size (about 2–3 cm wider) into fresh live or long-fibre sphagnum moss. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does kidney-leaved bladderwort need?

When is the best time of year to repot kidney-leaved bladderwort?

Can you put kidney-leaved bladderwort straight into a much bigger pot?

No. Even a fast-growing kidney-leaved bladderwort should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise kidney-leaved bladderwort after repotting?

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