Greater spearwort

Greater spearwort: how do you recognise it?

Habit

Upright, hollow stems up to 1 m tall; a clump about 50 cm wide that keeps spreading by runners.

Leaves

Long and narrowly lance-shaped, up to 25 cm, grey-green, with a smooth or finely toothed edge and no stalk.

Flowers

Glossy golden yellow, 3–5 cm across, with five petals, at the tips of the stems, from June to August.

Fruit

A small round head of small, dry seeds.

Roots

Creeping underground runners, which can also grow outside a basket.

Pond zone

Marsh zone and shallow water: from 0 to 20 cm below the water surface.

Flowering: June–August · Plants: April–June · Pruning: August and October

Why grow it?

• Large, glossy yellow flowers from June to August: one of the most eye-catching native pond plants.
• Tall, straight stems add height and structure to the pond edge.
• The flowers attract bees, hoverflies and beetles.
• The stems are a perch for dragonflies and damselflies, and frogs and tadpoles shelter around the base.
• Native and fully hardy.

Greater spearwort: where does it grow best?

• Full sun for rich flowering and sturdy stems; in shade it flops.
• Wet loam, clay or peaty soil, neutral to alkaline.
• Water depth 0–20 cm: in the marsh zone or in shallow water at the edge.
• Preferably sheltered from strong wind, as the tall stems can snap.
• Allow about 50 cm per plant; in a small pond one plant in a basket is enough.

Light

Sun

Soil type

Loam, clay or peat

Acidity

Neutral or chalky

Moisture

Wet

Size

1 m tall, 0.5 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Flowering rush: Pink flower heads in shallow water, in the same summer months.
• Purple loosestrife: Purple spikes on the bank: a fine contrast with the golden yellow.
• Arrowhead: Arrow-shaped leaves and white flowers at the same water depth.
• Water mint: A low, scented plant at the base, with lilac flowers for butterflies and bees.

Greater spearwort: when and how to plant it?

Plant in April–June.

1. Plant from April to June, when the plant is in growth.
2. Use an aquatic basket of at least 10 litres filled with heavy garden soil or clay, without potting compost or fertiliser.
3. Set the plant at the same depth as it was in the pot and top the soil with 2–3 cm of gravel.
4. Lower the basket until the base of the plant is 0–20 cm below the water surface; start shallower with young plants.
5. Keep about 50 cm from other plants so it does not overgrow them.

Care

Water

Not needed in the pond. In dry summers top up the pond with rainwater so the marsh zone does not dry out.

Feeding

Not needed: fertiliser in a pond mainly feeds algae.

Runners

In summer cut off runners that grow over the edge of the basket.

Support

In a windy spot the stems can lean on sturdier neighbours such as yellow flag.

Dividing

Every 2–3 years, when the basket is full, divide in spring.

Tip: Plant it in a sturdy basket at 0–20 cm depth and cut off every summer the runners that grow over the edge: then it will stay where you put it.

Greater spearwort: when to prune it?

Pruning months: August and October.

When: It needs little pruning. In August cut off spent stems and escaped runners, and in October cut the plant back.

How:

• Cut spent flower stems back to above a healthy leaf to keep the plant tidy.
• Cut off runners that grow over the edge of the basket and pull them out of the bottom with their roots.
• In October cut dead stems off above the water surface: they are hollow, and cutting them below water can make the base rot.
• Wear gloves and put the clippings on the compost heap, never in a field.

Caution: The fresh sap is poisonous and can irritate the skin: wear gloves and wash your hands afterwards.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In April–May take the plant out of its basket, cut the rhizome into pieces with a few shoots each and plant them in separate baskets.

Runners

In summer cut off a runner carrying a young, rooted plantlet and set it in a basket of wet soil.

Greater spearwort: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in a Belgian pond.
• The stems die back in autumn; the rhizome overwinters in the wet bottom.
• In a small tub: put it in a sheltered spot so the water does not freeze to the bottom.

Diseases and pests

• Spreading too much: New shoots far outside the basket. Cut off the runners and divide the basket every few years.
• Flopping stems: After wind or rain the stems lie flat. A sunny, sheltered spot and sturdy neighbours help.
• Few flowers: Too much shade or planted too deep. Raise the basket to 20 cm at most and give it more sun.
• Aphids: Aphids on stems and buds in summer. Hose them off; fish and pond creatures eat them. Never use pesticides near a pond.

Through the year

• April: Plant or divide. New shoots appear.
• May: Plant. Set the basket at the right depth.
• June: First large yellow flowers.
• July: In full flower. Cut off runners outside the basket.
• August: Last flowers. Cut off spent stems and runners.
• September: Top up the pond with rainwater if it stays dry.
• October: Cut dead stems off above the water surface, wearing gloves.
• November: Dormant. The rhizome overwinters in the bottom.

Edible and useful

Not edible. All parts of these buttercups are poisonous, especially when fresh: when the plant is damaged it releases protoanemonin, an acrid compound that causes a burning feeling in the mouth, drooling, vomiting and stomach ache, and redness and small blisters on the skin. The acrid taste puts most animals off: cows and horses leave fresh buttercups standing in the field, but in hay they are harmless, because the compound breaks down as it dries. So never throw fresh mowings or trimmings into a field, run or pen, and do not give them to rabbits or guinea pigs. Do not let children chew the stems or flowers, and wear gloves when dividing and trimming. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The species name lingua is Latin for tongue, after the long, tongue-shaped leaves.
• The shine of buttercups comes from a thin, mirror-like layer of cells at the top of the petals that reflects the light.
• Ranunculus means ‘little frog’: many species grow in wet places where frogs live.