Spanish broom

Spanish broom: how do you recognise it?

Habit

Upright, loose shrub 2–2.5 m tall and about 2 m wide, with many slender, straight, green twigs.

Foliage

Almost leafless: the small, narrow leaves fall early and the green, round twigs take over photosynthesis.

Flower

Bright yellow, pea-shaped, 2–2.5 cm, in loose spikes at the twig tips, June to August; strongly scented.

Fruit

Flat, black pods of 5–8 cm that burst open with a bang in late summer and fling out the seeds.

Roots

Deep taproot, living with nitrogen-fixing bacteria; they dislike being moved.

Flowering: June–August · Plants: April–May · Pruning: March

Why grow it?

• Flowers for months, from June to August, with bright yellow, strongly scented blooms.
• Green, rush-like twigs that give a light, exotic effect even outside the flowering season.
• Grows well on poor, dry soil, in full sun, on banks or in a gravel garden.
• The flowers attract bees: a rich source of nectar and pollen in summer.
• Fast-growing: makes a flowering 2 m shrub in a short time.

Spanish broom: where does it grow best?

• Full sun in a warm, sheltered spot, for example against a south wall.
• Poor, well-drained soil: sand, loam or clay rich in grit, acid to chalky. No waterlogged clay.
• Dry; it tolerates drought extremely well, but not permanently wet feet, especially in winter.
• Sheltered from cold, drying east wind; it is sensitive to hard frost.
• Allow 1.5–2 m per plant.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Dry

Size

2.5 m tall, 2 m wide

Hardiness

Hardy (to -15 °C)

Goes well with

• Lavender: Blue flowers and grey-green foliage in the same sun and dry soil.
• Rock rose: A Mediterranean shrub that likes the same dry, sunny spot.
• Rosemary: A scented, evergreen shrub for the same warm, dry soil.
• Ornamental grass: A fine grass as a soft counterpoint to the stiff, green twigs.
• Stonecrop: A low, drought-tolerant plant at the foot of the shrub.

Spanish broom: when and how to plant it?

Plant in April–May.

1. Plant in April–May, once the worst frosts are over, so that it can settle in before winter.
2. Buy it in a pot and ease it out gently: it has a taproot and dislikes being moved.
3. Dig a hole twice as wide as the root ball and mix in coarse sand or grit; add no compost or manure.
4. Set the plant at the same depth as in its pot and firm the soil gently.
5. Water in generously straight away, then in the first year only during prolonged drought.
6. Optionally spread a layer of gravel around the base and stake a young plant in a windy spot.

Care

Water

In the first year, water generously now and then in dry weather. After that it copes on its own, even in dry summers.

Feeding

Not needed: it fixes its own nitrogen from the air and likes poor soil. Feeding gives soft growth that is sensitive to frost.

Mulching

A layer of gravel or stones around the base keeps the soil dry and warm. No compost.

Seed pods

Cut the pods off in autumn to prevent seeding and keep the shrub tidy.

Pot

Use a large pot with plenty of drainage holes and a lean, free-draining compost mixed with grit.

Tip: Plant it young in spring against a south wall and prune it lightly every March, never into old wood. No feeding, and choose lean, gravelly soil.

Spanish broom: when to prune it?

Pruning months: March.

When: In March, before the new shoots appear. Prune lightly.

How:

• Shorten last year’s twigs by about a third, just above green, living shoots.
• Cut off frozen or dead twigs as soon as you can see where the new shoots break, usually in April–May.
• Remove dead and weak branches right at the base.
• A light yearly prune keeps it compact and stops it from becoming bare and woody.

Caution: Never cut back into old, bare wood: it does not regrow from there and the shrub may die. Stay within the young green twigs.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

In March–April: soak the seeds overnight in lukewarm water or nick them lightly. Sow them singly in small pots; it dislikes being moved. Seedlings flower after 2–3 years.

Semi-ripe cuttings

In July–August, take 8–10 cm cuttings of semi-ripe shoots in a sandy mix, under plastic. The failure rate is high, so take several.

Spanish broom: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Sensitive to hard frost: hardy to about −15 °C. In severe winters the twigs may freeze back.
• Give it a sheltered, sunny spot, for example against a south wall, and cover young plants with fleece in hard frost.
• In a pot: move it in frosty weather to a bright, frost-free place (a cold conservatory) and water hardly at all.

Diseases and pests

• Frost damage: Brown or dead twigs after a severe winter. Wait until May to see what regrows, then cut out the dead wood.
• Root rot: Yellowing and wilting on heavy, waterlogged soil. Improve drainage with grit or plant it on a bank.
• Bare and woody: Caused by too little pruning and shade. Prune lightly every March and give it full sun.
• Aphids: Colonies on young shoots in spring. Wash them off with water or let ladybirds and hoverflies do the work.

Through the year

• March: Prune lightly by a third. No feeding.
• April: Plant. Watch the young shoots.
• May: Plant. Cut out frost damage. Water young plants.
• June: Flowering begins: scented yellow flowers.
• July: Full flower. Bees in the garden.
• August: Flowering. Take semi-ripe cuttings.
• September: Cut off seed pods. Protect plants.
• October: Protect young plants before winter.
• November: Move pots to a frost-free place.
• December: Rest. Cover with fleece in frost.

Edible and useful

Not edible. Broom and Spanish broom are poisonous in all their parts, especially the seeds in the pods: their alkaloids cause nausea and vomiting, among other things. The flat pods look like those of peas or beans, and the yellow flowers are not edible flowers. Teach children not to open the pods, and do not plant broom in or next to a field: horses, sheep and goats, and dogs and cats too, can fall ill from it. 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 ripe pods burst open with a bang and fling the seeds several metres.
• In southern Italy, fibre was once taken from the stems to make cloth and rope.
• In warm regions outside Europe, such as California and Australia, it behaves as an invasive species.