Bittersweet

Bittersweet: how do you recognise it?

Habit

Climbing or sprawling subshrub of 1–3 m; the stems lean on or twine through other plants.

Leaf

Alternate, ovate to pointed heart-shaped, 4–10 cm, untoothed; often with 1–2 small ear-like lobes at the base.

Stems

Thin stems that are woody at the base and die back at the top every year.

Flower

Purple flowers (1–1.5 cm) with swept-back lobes and a yellow cone of anthers, in loose clusters, June–September.

Fruit

Oval berries (1 cm), green at first, then orange and glossy red when ripe, often all colours in one cluster, August–October; poisonous.

Difference from black nightshade

Black nightshade (Solanum nigrum) is an annual herb without woody stems, with white flowers and black berries.

Difference from white bryony

White bryony has curly tendrils, palmately lobed leaves and round berries.

Flowering: June–August · Pruning: November–March

Identify by feature: Purple or blue flowers · Red berries · Orange berries

Looks like it, but isn’t

• Black nightshade (Solanum nigrum): an annual herb without woody stems, with white flowers and black berries.
• White bryony Bryonia dioica: curly tendrils, palmately lobed leaves and round berries. Difference from white bryony

Why grow it?

• Native and easy, in damp places in sun, partial shade and even shade.
• Purple flowers from June to September and berries in three colours at once.
• Bumblebees shake the pollen out of the flowers by vibrating; thrushes and blackbirds eat the berries.
• Clothes a pond edge, wet bank or wild hedge with little care.

Bittersweet: where does it grow best?

• Sun, partial shade or shade; it flowers most freely in sun.
• Moist to wet soil: by a pond, ditch or stream, in a damp hedge or a small wet wood.
• It has no aerial roots or tendrils: its stems lean on or twine through shrubs, a fence or mesh. It does not harm walls, gutters or trees.
• Don’t plant it where small children play: the red berries are tempting and poisonous.

Light

Sun to shade

Legal basis

Any garden soil

Moisture

Moist to wet

Size

3 m tall, 1.5 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Alder: The tree of wet banks and alder carr, where bittersweet climbs through the understorey in the wild.
• Grey willow: A native willow for wet soil, through which bittersweet can twine.
• Guelder rose: A native shrub of moist soil, with white flowers in May and red berries in autumn as well.

Good and bad companions

Goes well with

• Tolerates shade and suits planting under large trees such as: ginkgo, box elder, ash, honey locust, field maple, silver maple
• Can climb into old, large trees: english oak, scots pine, sycamore, large-leaved lime

Bittersweet: when and how to plant it?

1. Plant in autumn or spring; nurseries specialising in native plants sell it in pots.
2. Plant it at the foot of a shrub, fence or bankside planting it can lean against.
3. On a pond bank, plant it just above the waterline, in wet soil.
4. It often also turns up by itself, as birds spread the seeds.

Care

Watering

Not needed in a damp spot; elsewhere in dry spells.

Feeding

Not needed.

Training

Guide the stems through a shrub or over a fence, or let them sprawl freely over the ground.

Seedlings

Birds spread the seeds: pull up unwanted seedlings while young.

Tip: Let bittersweet grow through a shrub or over a fence rather than over the ground: you will see the flowers and multicoloured berries better and keep it in check more easily.

Bittersweet: when to prune it?

Pruning months: November–March.

When: In winter (November–March).

How:

• Little needed: cut back overlong or dead stems.
• It readily reshoots from its woody base: a tangled plant can be cut back close to the ground.
• Clear up the prunings straight away, including any last berries.

Caution: Wear gloves and keep prunings with berries away from children and pets: the whole plant is poisonous.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

Cuttings of woody stems root easily, in winter straight into the ground outdoors or in summer in a small pot.

Layering

Stems lying on moist soil often root by themselves: dig them up and replant them.

Sowing

Sow the seeds from ripe berries outdoors in autumn; wash your hands afterwards.

Bittersweet: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy.
• The upper parts of the stems die back; the woody base reshoots in spring.
• The last berries sometimes hang on into winter and then feed blackbirds and thrushes.

Diseases and pests

• Rampant growth: Long stems that sprawl through the border or over small plants and take root. Cut them back and pull up rooted pieces.
• Berries and children: Red berries where small children play. Cut off the stems with berries in summer, or move the plant.
• Aphids: Aphids on the shoot tips in summer. Ladybirds and hoverflies usually clear them up.

Through the year

• January: Pruning: cut back overlong and dead stems.
• February: Pruning; push cuttings of woody stems into the ground.
• March: Last pruning before growth starts; planting.
• June: Flowering begins: small purple star flowers for bumblebees.
• August: The first berries turn from green through orange to red.
• September: Berries in all colours: food for thrushes and blackbirds.
• November: Pruning, or leave it until late winter; planting.
• December: Pruning: clear away dead stems.

What can you use it for?

For wildlife

Bumblebees shake the pollen out of the flowers by vibrating; thrushes and blackbirds eat the berries.

Garden and landscape

Suits a natural bank, pond edge or wild hedge.

Caution: The whole plant is poisonous, especially the unripe berries: take care with small children.

Did you know?

• The name describes the taste: if you chew a stem, it tastes bitter first and then sweet. Better not try it, though: the whole plant is poisonous.
• It is related to potato and tomato: just look at the flowers, with their yellow cone of anthers.
• Bumblebees shake the pollen out of the flowers with rapid vibrations: this is called buzz pollination.