Repotting guide

When & how to repot Humped Bladderwort (Utricularia gibba)

Also called Floating bladderwort.

More about humped bladderwort

About Humped Bladderwort

Utricularia gibba · also called Floating bladderwort · tropical

Humped bladderwort is a free-floating aquatic carnivorous plant that traps microscopic prey in tiny suction bladders along thread-like stems. It thrives in shallow, still, mineral-poor water under bright light and rewards patient growers with small yellow snapdragon-like flowers. It is fast-spreading, rootless, and easy in a bog or pond tray.

Mature size: Stems a few centimetres to over a metre long, but mat depth stays shallow; flower stalks rise 5-20 cm above the water.

How to tell humped bladderwort needs repotting

Repotting on a calendar is less reliable than reading the plant. For humped 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 humped 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 humped bladderwort

Every 12–18 months — sooner if roots show fast. Humped Bladderwort's growth habit — rootless, free-floating aquatic herb forming dense mats of fine branching stems studded with tiny bladders; sends up emergent flower stalks. — sets the pace. Humped bladderwort is a free-floating aquatic carnivorous plant that traps microscopic prey in tiny suction bladders along thread-like stems. It thrives in shallow, still, mineral-poor water under bright light and rewards patient growers with small yellow snapdragon-like flowers. It is fast-spreading, rootless, and easy in a bog or pond tray.

What size pot to step humped bladderwort up to

Step up one pot size — about 2–3 cm (an inch) wider. Humped 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 humped bladderwort

Early spring, just as new growth restarts, is the ideal window for humped 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 humped bladderwort

Time it for spring. Repot humped 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 humped bladderwort out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh none — grows free-floating in water 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 humped 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 humped bladderwort

Humped Bladderwort wants none — grows free-floating in water. Needs no soil. Grow in a tray or pot of mineral-free water, optionally over a thin layer of pure peat or sand; the stems float and tangle near the surface. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting humped bladderwort — frequently asked questions

How often should you repot humped bladderwort?

Every 12–18 months — sooner if roots show fast for humped bladderwort. Repot humped 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 none — grows free-floating in water. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does humped bladderwort need?

When is the best time of year to repot humped bladderwort?

Can you put humped bladderwort straight into a much bigger pot?

No. Even a fast-growing humped 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 humped bladderwort after repotting?

Not immediately. Wait about 4 weeks after repotting humped 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.