Greater bladderwort

Greater bladderwort: how do you recognise it?

Habit

Free-floating water plant without roots, with long, branched stems up to about 1 m just below the surface.

Leaves

Finely divided into thread-like segments, light to olive green, set with numerous bladders a few millimetres across.

Flower

Bright yellow, about 1.5 cm, with a spurred lip like a snapdragon, in a loose cluster on a sturdy stalk 10–20 cm above the water, in July and August.

Bladders

Tiny traps with a trapdoor and trigger hairs: when a creature touches the hairs, the door opens and it is sucked inside in a fraction of a second.

Winter buds

In autumn it forms compact green buds at the stem tips, which sink to the bottom and grow again in spring.

Flowering: July–August · Plants: May–July · Pruning: August

Why grow it?

• A true carnivorous plant for the pond: its bladders catch water fleas and small mosquito larvae.
• Bright yellow flowers above the water in July and August, a surprising sight in a wildlife pond.
• It floats freely: no basket, no soil and no feeding needed.
• The dense tangle of stems shelters tadpoles, dragonfly and damselfly larvae and other small pond creatures.
• Native and fully hardy: it overwinters as a bud on the bottom and returns every spring.

Greater bladderwort: where does it grow best?

• Full sun: it grows and flowers best in warm, clear water.
• Still, soft, nutrient-poor water, acid to neutral, as in a heathland pool or a pond filled with rainwater.
• A water depth of at least 30–50 cm, so that the pond does not freeze to the bottom in winter.
• Ideally a pond without goldfish or koi: they eat or damage the fine stems.
• One square metre of water surface is enough for a few plants; it spreads on its own.

Light

Sun

Soil type

Peat

Acidity

Acid or neutral

Moisture

Wet

Size

0.2 m tall, 0.5 m wide

Hardiness

Hardy (to -25 °C)

Goes well with

• Frogbit: A small floating plant with round leaves that, like bladderwort, overwinters as a bud on the bottom.
• Water soldier: Spiky rosettes in the water in which the green hawker, a dragonfly, lays its eggs.
• Water violet: A native oxygenating plant with lilac flowers in May–June, for the same soft water.
• Bogbean: White, fringed flowers in the marsh zone of a nutrient-poor pond.

Greater bladderwort: when and how to plant it?

Plant in May–July.

1. Put it out from May to July, once the water has warmed up.
2. Rinse new plants in a bucket of rainwater first, so you do not bring in snails, duckweed or blanket weed.
3. Simply let the plant or a piece of stem float in the water: it needs no basket and no soil.
4. Choose a calm, sunny spot among other water plants, away from a pump or fountain.
5. Top up the pond with rainwater, not tap water, which is often too limy and too rich.

Care

Water

Keep the level up with rainwater. Limy or nutrient-rich water slows growth.

Feeding

Never: it takes its food from the water and from its prey. Fertiliser only feeds algae.

Blanket weed

Gently pick blanket weed out of the plant by hand or with a stick, so it does not smother the fine stems.

Thinning

If it grows too dense, remove part of the stems in August; leave them on the bank for a day so pond creatures can return.

Fallen leaves

In autumn, net fallen tree leaves out of the water: rotting leaves make the pond richer in nutrients.

Tip: Only top up the pond with rainwater and never feed: it grows best in soft, nutrient-poor water, where blanket weed also has less chance.

Greater bladderwort: when to prune it?

Pruning months: August.

When: It does not really need pruning. If it grows too dense, thin it in August.

How:

• Gently pull part of the stems out of the water by hand or with a pond rake.
• Leave at least half in place, so there is enough plant left to form winter buds.
• Leave what you remove on the bank for a day, so tadpoles and larvae can crawl back into the water.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Stem pieces

In summer, break off a piece of stem 10–20 cm long and let it float in other soft, nutrient-poor water. Each piece grows into a new plant.

Winter buds

In autumn, fish out a few winter buds and keep them in a bucket of rainwater in a cool place; in April–May they start growing and can be put out.

Greater bladderwort: how does it get through the winter?

Hardy to −25 °C.

• Fully hardy, to about −25 °C: no protection is needed in a Belgian pond.
• In autumn the stems die back and the winter buds sink to the bottom; in spring they rise again and start growing.
• Do not worry if the plant seems to vanish in winter: that is normal.
• In a tub or small container that can freeze solid, keep the buds in a bucket of water in a cool, frost-free place.

Diseases and pests

• Blanket weed: Green threads tangle in the stems and smother the plant. Remove by hand and add as few nutrients to the water as possible.
• Poor growth: Pale, short stems in limy or nutrient-rich water. Top up with rainwater and remove rotting leaves.
• Fish: Goldfish and koi eat or damage the fine stems. It does best in a pond without fish.
• No flowers: Too little sun or a cool summer. Place it in the sunniest part of the pond; flowering varies from year to year.
• Gone in winter: No problem: the plant overwinters as a bud on the bottom and returns in spring.

Through the year

• March: Top up the pond with rainwater. Remove fallen leaves.
• April: The winter buds rise and start growing.
• May: Put out new plants. Remove blanket weed.
• June: Still time to put out plants. The stems grow fast.
• July: First yellow flowers above the water. Still time to put out plants.
• August: Flowering. Thin if too dense. Top up with rainwater.
• September: Winter buds form at the stem tips.
• October: The buds sink to the bottom. Net fallen leaves out of the pond.
• November: Resting on the pond bottom.

Did you know?

• The bladders work by suction: when a creature touches the trigger hairs, it is sucked inside in a fraction of a second. It is one of the fastest movements in the plant kingdom.
• Greater bladderwort has no roots at all: it takes up nutrients through its leaves and from the prey it catches.
• The genus Utricularia is the largest genus of carnivorous plants, with more than 200 species worldwide.