Spike lavender

How to recognise it

Growth habit

Evergreen, compact dwarf shrub of 30–60 cm, woody at the base, with flower stems reaching about 80 cm.

Leaf

Opposite, oblong to spoon-shaped, 3–6 cm, clearly broader than in true lavender, grey-green and densely felted. Smells of camphor when crushed.

Flower

Small, two-lipped, pale lilac to greyish-blue flowers in slender spikes on long, bare stems. The stems are often branched, with two smaller side spikes below the main spike. Narrow, green bracts. Flowers in July–September.

Fruit/Seed

Four small brown nutlets inside the persistent calyx, ripe in autumn.

Roots

A deep, woody root: older plants do not like being moved.

Confusion with

True lavender (Lavandula angustifolia) has narrower leaves, unbranched stems with a single spike and broad brown bracts, and flowers earlier, in June–July. Lavandin (Lavandula × intermedia), a hybrid of the two, grows larger, with long spikes on often branched stems. French lavender (Lavandula stoechas) has plump spikes topped with purple ‘ears’.

Flowering: July–September · Pruning: April and September

Why grow it?

• Late flowering from July into September, when many other lavenders have finished: welcome nectar for honeybees, bumblebees and wild bees.
• Butterflies such as whites and peacocks also visit the flowers.
• Evergreen grey foliage that gives year-round structure to a gravel garden or dry border.
• Copes with heat and drought once established: a climate-proof plant that needs hardly any water.
• The flower stems are lovely for drying; the scent is sharper and spicier than that of true lavender.

Spike lavender: where does it grow best?

• In the wild: dry, stony limestone slopes, garrigue and open oak and pine woodland, at lower altitudes than true lavender.
• In the garden: full sun, warm and sheltered, ideally facing south or against a sunny wall.
• Poor, very free-draining soil, chalky to neutral: sand, gravel or rubble. Heavy, wet clay in winter is fatal.
• Lovely in a gravel garden, a rock garden, along a sunny path or in a large pot with plenty of drainage.

Goes well with

• Wild marjoram: Pink flower heads in the same summer, also a magnet for bees on dry soil.
• Thyme: A fragrant, low ground cover at the front that flowers earlier.
• Rosemary: Another Mediterranean shrub with the same needs: sun, gravel and no wet feet.
• Catmint: Lavender-blue flowers from May, providing nectar before the spike lavender flowers.
• Sage: Grey leaves and purple flowers for a Mediterranean herb corner.

Spike lavender: when and how to plant it?

1. Buy it from a nursery or garden centre and check the label carefully: Lavandula latifolia. Never take plants from the wild, not even on holiday in Spain or France.
2. Plant in April–May, so it is well rooted before winter.
3. Lighten heavy soil with gravel or grit, or plant on a raised bed. Do not add compost or fertiliser.
4. Set the plant at the same depth as in its pot, firm the soil and give it a good can of water.
5. Allow 50–60 cm between plants. In a pot, use compost mixed with one third gravel, in a pot with drainage holes.
6. Mulch around the base with gravel, not bark: bark holds too much moisture.

Care

Water

In dry spells during the first weeks after planting. After that hardly ever; in a pot now and then, when the compost is completely dry.

Feeding

Do not feed: fertiliser makes it floppy, less fragrant and less hardy.

Winter wet

Wet feet in winter are more dangerous than frost. In winter, move a pot under cover and never wrap the plant in plastic.

Gravel mulch

A layer of gravel keeps the base and lower leaves dry and reflects the warmth.

Harvesting

Cut flower stems for drying when the first flowers have just opened and hang them upside down in a dry, airy place.

Tip: Plant spike lavender next to true lavender: true lavender flowers in June–July, and spike lavender takes over until September. That way the bees have fragrant lavender for months.

Pruning and mowing

Pruning months: April and September.

When: After flowering, in September, cut off the spent stems; in April, lightly trim the plant into shape.

How:

• In September, cut the spent flower stems back to just above the foliage.
• In April, as new growth starts, trim the leafy cushions by 2–3 cm, staying within the green, leafy part.
• Keep a rounded, compact shape: this stops the shrub from splaying open and keeps it looking good for years.

Caution: Never cut into bare, old wood: it will not regrow from there. Do not cut too hard in autumn either, as that makes it more vulnerable to frost.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

Semi-ripe cuttings of 8–10 cm from non-flowering shoots in August–September, in sandy cutting compost. Overwinter them dry and frost-free and plant them out in spring.

Seed

Sow indoors in March–April at 15–20 °C, thinly and barely covered. Seedlings may differ somewhat from the parent plant.

Spike lavender: how does it get through the winter?

Hardy to −12 °C: protect in harsh winters.

• Evergreen: the grey foliage stays on all winter.
• Less hardy than true lavender: down to about −12 °C on dry soil. Wet soil and frost together are fatal.
• In winter, place a potted plant against a south-facing wall under cover, or frost-free in a cool, bright room.
• Leave the shrub alone in winter; only cut off frosted tips in April.

Diseases and pests

• Root rot: The plant turns grey and dies on wet, heavy soil. Plant on a raised, gravelly spot and do not water in winter.
• Rosemary beetle: Shiny beetles striped in green and purple, and their grey larvae, eat the leaves, mainly from autumn to spring. Shake them onto a newspaper and remove them.
• Bare and woody: Without yearly pruning the plant splays open and goes bare at the base. Trim lightly every spring and replace old, bare plants.
• Cuckoo spit: White blobs of froth on the stems in May–June, with a froghopper nymph inside. Harmless; hose them off if they bother you.
• Frost damage: Brown, withered tips after a hard winter. Wait until April and then cut off only what is really dead.

Through the year

• January: Rest. Grey foliage in the winter garden; keep a pot dry.
• April: Trim lightly into shape, staying in the green. Plant.
• May: Plant. Look out for cuckoo spit.
• June: The flower stems shoot up.
• July: Flowering begins: bees and bumblebees on the lilac spikes. Cut stems for drying.
• August: In full flower. Take semi-ripe cuttings.
• September: Last flowers. Cut off the spent stems. Take cuttings.
• October: No more pruning. Look out for rosemary beetles.
• November: Move a pot under cover, out of the winter wet.
• December: Rest. Do not water.

Did you know?

• Latifolia means ‘broad-leaved’: its leaves are broader than those of true lavender, which is why that species is called angustifolia, ‘narrow-leaved’.
• Where spike lavender and true lavender grow together in southern France, they cross naturally. This hybrid, lavandin, is now grown in many lavender fields in Provence.
• Painters used to thin oil paint and varnish with oil of spike, the oil of this lavender. Both ‘spike’ and the French aspic go back to the Latin spica, ‘ear of grain’.