Foxglove tree

Foxglove tree: how do you recognise it?

Habit

Fast-growing tree of 10–15 m with a broad, rounded, fairly open crown and thick twigs.

Leaf

Opposite, 15–30 cm (up to 60 cm on young shoots), broadly heart-shaped, untoothed or with a few angular lobes, softly hairy on both sides.

Bark

Greyish-brown and smooth, with pale dots (lenticels).

Flower

Upright panicles of fragrant, lavender-blue bell flowers in May. The brown, felted buds are ready all winter.

Fruit

Egg-shaped, pointed, woody capsules (3–4 cm) full of winged seeds.

Difference from Indian bean tree

The Indian bean tree has leaves often in threes and less hairy; it flowers white in July and bears long, thin ‘beans’.

Flowering: April–May · Pruning: February–March

Identify by feature: Heart-shaped leaves · Opposite leaves · Purple or blue flowers

Looks like it, but isn’t

• Indian bean tree Catalpa bignonioides: leaves often in threes and less hairy; white flowers in July and long, thin ‘beans’. Difference from Indian bean tree

Why grow it?

• Spectacular, fragrant lavender-blue flowers in May, on bare branches.
• Grows at lightning speed: a shade tree within a few years.
• Coppiced every year, it produces leaves up to 60 cm across for a tropical feel, and then sets no seed.
• To be honest: it is of little value to native insects, apart from bumblebees at flowering time. If you want a shade tree for wildlife, choose a native tree.

Foxglove tree: where does it grow best?

• Full sun and a warm, sheltered spot: wind tears the large leaves.
• Any well-drained soil that isn’t too wet; it also tolerates urban soil.
• As a tree, allow for a crown about 8 m across: then it only suits a large garden. Coppiced every year, it stays a shrub of 2–3 m, fine for a smaller garden too.
• Don’t plant it near woodland, nature areas or railway lines, where seedlings could escape into the wild.

Light

Full sun

Legal basis

Any garden soil

Moisture

Normal

Size

12 m tall, 8 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Small-leaved lime: The native choice if you want a shade tree: its fragrant July flowers feed bees, and it is far more valuable to wildlife.
• Indian bean tree: Also has large, heart-shaped leaves, but white flowers in July: together a tropical feel in a large garden.
• Japanese aralia: Large, glossy evergreen leaves for the partial shade under a coppiced foxglove tree: a jungle effect.

Good and bad companions

Goes well with

• Tolerate the shade under this tree: oregon grape, rhododendron, oleaster, japanese skimmia, garden privet, camellia, laurustinus, box-leaved honeysuckle

Foxglove tree: when and how to plant it?

1. Plant in spring (April–May), container-grown: it then has time to root in before winter.
2. Young plants are frost-tender: protect the base with a thick layer of mulch for the first few winters.
3. Dig a generous planting hole and mix in compost; water during dry spells in the first year.
4. Still in two minds? A native shade tree such as small-leaved lime also has fragrant flowers, feeds bees and is worth far more to wildlife.

Care

Watering

During dry spells in the first year. Coppiced plants with giant leaves lose a lot of water and need watering in dry summers.

Feeding

Only if you coppice it every year: a little compost or well-rotted manure in spring, for big leaves.

Seedlings

Near a flowering tree, look for seedlings in paving cracks, borders and gravel, and pull them up.

Suckers

After hard pruning or felling, it can resprout from the stump and roots: cut off those shoots if you don’t want them.

Tip: Want the tropical look without the risk of it spreading? Coppice it every spring: you get leaves up to 60 cm across, and a plant that doesn’t flower doesn’t set seed.

Foxglove tree: when to prune it?

Pruning months: February–March.

When: End of winter, before growth starts.

How:

• As a tree: formative pruning only. Remove dead, crossing and badly placed branches and keep a single trunk.
• For giant leaves, coppice it every spring to 30–50 cm above the ground. Of the new shoots, keep only the strongest.
• A coppiced foxglove tree won’t flower, as the flowers form on the previous year’s wood; so it won’t set seed either.

Caution: On a flowering tree, don’t cut back the branch tips: that is where the flower buds sit, ready from autumn onwards.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Best not

Better not to propagate it: it already spreads by seed. If you do want a second plant, take root cuttings of 5–10 cm in winter, lay them in a pot of sandy compost and keep it frost-free; they shoot in spring.

Seedlings

Seedlings that come up by themselves are best pulled up, especially near woodland or nature areas.

Foxglove tree: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• The tree itself is hardy, but young plants and unripened shoot tips are cut back by frost in harsh winters; they grow back in spring.
• The flower buds are ready all winter and can freeze in a harsh winter: it then flowers little or not at all that year.
• The leaves drop at the first night frost, without any real autumn colour.

Diseases and pests

• No flowers: Frozen flower buds after a harsh winter, or yearly coppicing: then there are no flower buds. A warm, sheltered spot helps.
• Frost-damaged shoots: Black, dead shoot tips after winter, especially on young trees. Cut them back to healthy wood in March.
• Torn leaves: The large leaves tear in the wind. Plant it in a sheltered spot.
• Seedlings: The winged seeds blow a long way and germinate in paving cracks, gravel and bare soil. Pull them up while young.

Through the year

• February: Coppice for giant leaves, or formative pruning of a tree.
• March: Finish pruning; cut off dead shoot tips.
• April: Plant container-grown trees; give compost to coppiced plants.
• May: Flowering: fragrant, lavender-blue bells for bumblebees.
• July: Water coppiced plants during dry spells.
• September: Pull up seedlings nearby; the capsules ripen.
• November: The leaves drop at the first frost; mulch around young plants.

What can you use it for?

Garden and landscape

Fast-growing shade tree with purple spring flowers; coppiced, it produces enormous leaves.

Wood

Very light but strong wood: boxes, surfboards and musical instruments.

For wildlife

The early flowers are good for bumblebees.

Caution: Self-seeds in warm regions; in Central Europe it sometimes escapes along railway lines.

Good for wildlife

Bumblebees

Nectar and pollen for bumblebees, also from deep flowers and early in spring.

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• Named after Anna Paulowna, the Russian grand duchess who became Queen of the Netherlands. In Japan the light wood is used to make kimono chests.
• The wood is very light but strong: it is also used for surfboards and musical instruments.
• In Japan it is called ‘kiri’; its leaves and flowers feature in the emblem of the Japanese government.
• The tree was described by Philipp Franz von Siebold, the German physician who worked for the Dutch on the trading island of Dejima in Japan.
• A stylised paulownia, three leaves topped with flower clusters, is the emblem of the Japanese government and prime minister.