Twinberry

Twinberry: how do you recognise it?

Habit

Upright, dense shrub about 2 m tall and as wide, with sturdy grey-brown stems.

Leaves

Opposite, ovate to elliptic, 5–12 cm long, fresh green; deciduous.

Flowers

Yellow tubular flowers 1–2 cm long, always in pairs in the leaf axils, from May to July.

Bracts

Two pairs of bracts surround the flowers; they enlarge and turn bright to dark red as the fruit ripens.

Fruit

Glossy black berries about 1 cm across, always in pairs; mildly toxic to people but popular with birds.

Flowering: May–July · Plants: March–April and October–November · Pruning: February–March

Why grow it?

• A long flowering season from May to July, then a second season of interest from the black berries in their red collars.
• Bumblebees and other bees readily visit the yellow tubular flowers.
• Birds eat the ripe berries in summer and early autumn.
• Very hardy and tough: it tolerates wet soil, wind and salt spray.
• Good for an informal hedge, a coastal windbreak or a wildlife garden with a damp corner.

Twinberry: where does it grow best?

• Full sun to partial shade; in sun it flowers best and sets the most berries.
• Not fussy: sand, loam, clay or peat, from acid to chalky.
• Moist to wet soil: ideal beside a pond, a ditch or in a low, damp corner. It copes less well with long droughts.
• Tolerates wind and salt spray, so it also suits coastal gardens.
• Allow 1.5–2 m per plant; for an informal hedge, plant 80–100 cm apart.

Light

Sun and partial shade

Soil type

Sand, loam, clay or peat

Acidity

Not fussy

Moisture

Normal or wet

Size

2 m tall, 2 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Red-barked dogwood: Red winter stems and the same liking for wet soil.
• Guelder rose: A native shrub for damp soil, with white flowers and red berries for birds.
• Meadowsweet: Creamy, scented plumes at its feet in summer, on wet soil.
• Purple loosestrife: Purple-pink spikes in summer along the edge of a pond.
• Ferns: A fresh green underplanting in partial shade.

Twinberry: when and how to plant it?

Plant in March–April and October–November.

1. Plant in March–April or October–November, when the soil is neither frozen nor waterlogged.
2. Dig a hole twice as wide as the root ball and loosen the bottom of the hole.
3. Set the shrub at the same depth as it was in its pot and backfill with soil, mixed with a little compost if you like.
4. Firm the soil well and water in thoroughly straight away.
5. Spread a mulch of wood chips or leaf mould around the base and water during dry spells in the first year.

Care

Watering

Regularly in dry weather during the first year. After that only in long dry spells, especially on sandy soil.

Feeding

Not needed on ordinary garden soil; a little compost in spring is enough.

Mulching

A mulch keeps the soil moist and suppresses weeds around young plants.

Berries

Leave them for the birds. They are not edible for people.

Rooting stems

Stems that touch the ground sometimes root. Cut them off or use them to make new plants.

Tip: Plant it where other shrubs drown or get blown about: in a wet corner or an exposed spot by the sea. Leave the berries for the birds.

Twinberry: when to prune it?

Pruning months: February–March.

When: Hardly any pruning is needed. Thin the shrub every few years in February–March, before it comes into leaf.

How:

• Cut a few of the oldest, thickest stems out at the base; this keeps the shrub young and open.
• Remove dead, damaged and crossing stems.
• Too big or bare at the base? It tolerates hard renovation pruning to 30–50 cm above the ground, but will flower less for a year.

Caution: Every cut costs flowers and berries: stick to thinning and do not shorten every stem.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

Softwood cuttings in June–July under plastic, or 20 cm hardwood cuttings in winter, straight into the ground. They root easily.

Layering

In summer, peg a low stem into the soil; after a year it will have rooted and can be severed.

Seed

Sow seed from ripe berries in autumn in a pot outdoors: it needs a cold period and germinates in spring.

Twinberry: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy to about −30 °C: no protection is needed in Belgium.
• It drops its leaves in autumn and comes into leaf early in spring.
• It also grows in a large pot or container, as long as excess water can drain away.

Diseases and pests

• Aphids: On young shoots in spring. Ladybirds and other natural predators usually deal with them; otherwise spray them off with water.
• Powdery mildew: White powder on the leaves in dry summers. Keep the soil moist and the shrub open; cut out badly affected shoots.
• Few flowers and berries: Usually too much shade or too much pruning. Give it more light and only thin it.
• Bare base: Older shrubs become bare at the bottom. Rejuvenate by removing a few old stems at the base every year or two.

Through the year

• February: Thin out: cut a few old stems at the base. Take hardwood cuttings.
• March: Plant. Remove dead wood. Add compost.
• April: Plant. The shrub comes into leaf; watch for aphids.
• May: Flowering starts. Bumblebees on the yellow flowers.
• June: Full flower. Take softwood cuttings.
• July: Last flowers; the bracts turn red and the first black berries ripen.
• August: Berries for the birds. Water during long dry spells.
• October: Plant.
• November: Plant. Leaf fall.
• December: Rest. Take hardwood cuttings.

Edible and useful

Not edible. The glossy red or black berries of these honeysuckles are mildly poisonous: eating more than a few can cause stomach ache, vomiting and diarrhoea, and dogs and cats fall ill from them too. They hang from summer into autumn, often at a child’s height on a climber along a fence or on a shrub. Do not confuse them with the honeyberry (Lonicera caerulea), the honeysuckle grown for its edible berries: those are elongated and blue with a waxy bloom, and ripen in May and June; the berries of these honeysuckles are red or black and are not for eating. Teach children that the berries are for the birds, and pick them off where toddlers play. Birds, however, eat them without harm. 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.

Birds

Berries, seeds or insects as food, or a place to nest.

Did you know?

• The species name involucrata refers to the involucre: the ring of bracts around the flowers and later the berries.
• The name twinberry comes from the berries, which always hang in pairs on a single stalk.
• In its native range the shrub is pollinated not only by bumblebees but also by hummingbirds.