Growing lavender in a cold climate: the complete guide

Growing lavender at a glance

Contents

• Growing lavender at a glance
• Why does lavender die over winter?
• English lavender, lavandin, Spanish and French lavender
• Cold-hardy lavender varieties worth buying
• Building a well-drained planting site
• How to plant lavender step by step
• Spacing and growing a lavender hedge
• How often should you water lavender?
• Why you should not feed lavender
• Gravel mulch instead of bark
• When and how should you prune lavender?
• Winter protection that works in zone 4
• Growing lavender in pots and overwintering them
• Harvesting and drying lavender
• Propagating lavender from cuttings
• Lavender for bees and butterflies
• Why lavender goes woody, and when to replace it
• Zone table: lavender in USDA zones 3–7
• Common mistakes
• Frequently asked questions

Why does lavender die over winter?

The usual explanation is that it froze. That is almost always wrong. Established English lavender takes −20 to −25 °C (−4 to −13 °F) at the root when the soil is dry. It does not take a winter with water standing around the crown at freezing point.

Lavender roots evolved on dry limestone hillsides with no defence against airless, saturated soil. Once the surface freezes and meltwater cannot drain, the roots sit in a closed puddle, and the fungi behind root rot work at low temperatures. In spring the plant looks grey, so you blame the cold. What actually happened is that the crown rotted in March. The Royal Horticultural Society puts it plainly: lavender will not thrive in heavy clay or soil that becomes waterlogged over winter. Northern Gardener, in Minnesota, agrees from the other direction — root rot from overwatering is lavender's worst enemy.

Three sites kill lavender reliably: a low spot in the lawn, the ground under a downspout, and a new bed of bagged garden soil. One keeps it alive: the strip between a gravel path and a south-facing wall. That is where you find ten-year-old lavender in zone 4.

English lavender, lavandin, Spanish and French lavender

Labels rarely say which species is in the pot, and the species is the difference between a plant that lives twelve years and one that is compost by May.

English lavender (Lavandula angustifolia)

The only lavender to plant permanently in zones 4 and 5. Narrow grey-green leaves, short flower stems, bloom in July, and a sweeter scent with less camphor than its relatives. Named cultivars are generally rated zones 5–8 and several zone 4. Height 30–60 cm (12–24 in). It is the species grown for culinary use.

Lavandin (Lavandula x intermedia)

A cross between angustifolia and the tender Lavandula latifolia, sold as Dutch lavender, and the plant behind the purple field photographs from Provence. Bigger at 60–90 cm (24–36 in), with long stems, blooming two to three weeks later. Hardiness runs a step lower, roughly −15 to −18 °C (5 to 0 °F), so most are rated zone 5 and marginal in zone 4. 'Phenomenal' and 'Sensational' were selected for better cold tolerance.

Spanish and French lavender will not overwinter

Lavandula stoechas, sold as Spanish or butterfly lavender, is easy to spot: a short fat flower head topped with large purple bracts like rabbit ears. It is rated zones 8–11. True French lavender, Lavandula dentata, has toothed grey leaves and is no hardier. Neither survives a zone 3–6 winter in the ground — buy them as summer container plants.

Cold-hardy lavender varieties worth buying

Hardiness varies less between cultivars than between species, but height, colour and density differ. All of these are widely sold in North America and Britain.

Sources disagree about 'Phenomenal': some nurseries rate it zone 4, others zone 5. Treat it as zone 5 unless you can give it a raised bed against a south wall.

Building a well-drained planting site

With gravelly soil in full sun, go straight to planting. With clay or a flat bed, you need to build.

South wall, mound and slope

A south-facing wall stores the day's heat, keeps a strip drier under the eaves and breaks the wind that desiccates foliage over frozen ground. The warmest band is 30–60 cm (12–24 in) out from the foundation, and south wall plus gravel is worth roughly a zone.

The RHS gives a usable number for heavy soil: plant on a mound, ridge or raised bed 20–30 cm (8–12 in) high, so the crown sits above the level where water stands. A raised bed works if you fill it with a gritty mix, not bagged soil. A slope is free drainage — plant in the upper half. Gravel in the bottom of a hole does not help in tight clay; build up, not down.

Soil and pH

Lavender wants soil most garden plants would complain about: lean, stony, fast draining, neutral to slightly alkaline. UC IPM gives pH 6.5–7.5; Northern Gardener widens it to 6.0–8.0. Acidic, fertile soil is wrong at both ends — it holds water and pushes soft growth.

A working bed mix is one third native mineral soil, one third coarse sand or grit 0–4 mm, and one third angular gravel 8–16 mm (3/8–5/8 in). Never mix fine sand into clay: the clay fills the pores between sand grains and the result behaves like concrete, which Northern Gardener warns about.

If a test shows pH below 6.0, raise it with garden lime at 100–200 g per square metre (3–6 oz per square yard) worked into the top 20 cm (8 in). More on soil for the herb patch is in the guide to growing herbs.

How to plant lavender step by step

Plant in spring after the last frost, through early June. The RHS is blunt: never plant lavender in winter, when young plants are vulnerable to rotting.

1. Pick the sunniest spot. Six hours of direct sun minimum. Check how it looks after heavy rain.
2. Clear every perennial weed. Couch grass in a gravel bed is impossible to remove later.
3. Mix the bed, 40 cm (16 in) deep and 50 cm (20 in) wide per plant.
4. Raise the surface 20–30 cm (8–12 in) above grade in heavy soil; level is fine in sand.
5. Soak the pot in a bucket until the bubbles stop, then tease the root ball and straighten roots that circled it.
6. Dig a shallow hole, exactly as deep as the root ball is tall, so the top of the ball sits level with the surface or a little above.
7. Set the plant, backfill firming with your palm, and water in with 3–5 litres (1 gal), soaking the whole bed.
8. Spread gravel 3–5 cm (1–2 in) deep in a circle 40–50 cm (16–20 in) across, leaving 3 cm (1 in) bare at the stem base.
9. Pinch off the first summer's flower buds on a small plant, for a denser shrub next year.

Spacing and growing a lavender hedge

Too close gives grey mould and bare legs; too far, the hedge never closes.

Buy every plant of one cultivar in one delivery for an even hedge; mix 'Hidcote' and 'Munstead' and you get two bloom times and two heights. A double staggered row is denser but cuts air movement, so in zone 4 and colder a single row is safer. Edging a vegetable garden, lavender also pulls in beneficial insects, the same thinking as companion planting.

How often should you water lavender?

A lot in the first season, almost never after that. Overwatering is the second biggest killer after the wrong site. A new plant has roots only in the original ball, which dries fast in a gravel bed. Water the soil, not the foliage — UC IPM recommends drip irrigation, since overhead watering spreads disease.

You are watering too much if leaves yellow in the middle of the shrub, shoots flop, there is a sour smell at the base, or it refuses to flower in full sun. Drought stress looks different: greyer leaves, hard shoots, earlier bloom. A lavender that looks slightly dry is in better shape than a lush one.

Why you should not feed lavender

The RHS says it directly: lavender likes soil low in nutrients and does not generally need feeding. In a cold climate that matters even more, because of hardiness.

Nitrogen drives long, soft shoots with thin cell walls. They flower less and do not harden before frost, so a fed lavender goes into winter with growth that kills back to the base. Heavy growth also makes the shrub floppy: it splits open and rain collects in the gap, where grey mould starts.

In pure sand, or in a pot, one weak low-nitrogen feed at half strength in late spring is enough. Manure and compost teas belong on your raised bed vegetables.

Gravel mulch instead of bark

Use gravel. Spread 3–5 cm (1–2 in) of pale chippings or crushed stone 8–16 mm (3/8–5/8 in) around the plant. Gravel lets water straight through, dries fast at the surface, holds no moisture against the stem and reflects heat into the shrub. Northern Gardener recommends it for that reason.

Do not use bark, compost or grass clippings. Organic mulch holds moisture, breaks down into nutrients and lies like a wet blanket against the crown. Bark against a stem causes crown rot within a couple of seasons. Leave 3 cm (1 in) of bare soil at the woody base — that is where crown rot begins.

When and how should you prune lavender?

Pruning separates a lavender that lives twelve years from one that is a grey skeleton at five. Lavender is a subshrub: it builds new wood on last year's wood, and old wood makes no buds.

The rule you never break

Never cut into bare brown wood. The RHS phrases it as lavender not breaking new growth easily from old stems, so a cut there leaves a stub that never regrows. Look at a stem first: the top is green with paired leaves, below that a short zone with scattered leaf buds, then bare brown wood. Cut in the middle zone and leave 2–5 cm (1–2 in) of green with visible buds.

Spring or late summer in a cold climate?

Your zone decides. In mild Britain the main cut comes in late summer straight after flowering; in zones 3–5 that is risky. Purdue Extension is explicit: wait until new growth begins in spring, because lavender is only marginally hardy and autumn pruning can kill the plant. A late cut pushes soft shoots that never harden, and open wounds let rot in.

• Main cut in spring. Late April to early June depending on zone, as soon as the first green shoots show. Spring is also when you can finally tell live stems from dead ones. Shape the plant into an even dome and take about a third of last year's growth, stopping above the brown wood.
• Light trim after flowering. Cut spent stalks plus 2.5 cm (1 in) of leaf growth once bloom is over, usually August. In zone 3–4 skip it and let the dry stalks stand as winter cover.

Work on a dry day with sharp shears, since crushed cuts rot. Scratch a doubtful stem with a thumbnail: green under the bark means live, brown means dead. Take dead stems out at the base and shape the rest into a low dome.

A plant already bare at the bottom cannot be cut back in one go. Work over three years: take a third of the stems slightly harder than usual, always to a point with a live leaf bud. If those break, repeat the next year.

Winter protection that works in zone 4

Winter cover is not there to keep lavender warm. It is there to keep it dry, shade it from winter sun and slow the drying wind over frozen ground.

Use evergreen boughs. Spruce, fir or pine branches are best for one reason: they are open. They break wind and light without forming a solid lid. Lay them loosely over the plant once the ground has frozen, usually late November, and remove them in April before growth starts, or they become a moisture trap.

Do not pack it with leaves. Wet leaves mat into a dense, airless layer that holds water against stems and crown all winter — precisely what root rot needs. The same goes for pressed-down straw, plastic sheet, fleece on the plant and compost over the base. Straw and burlap, often suggested for snowless zone 4, work only if they stay loose and off the crown.

Even snow cover is the perfect lavender winter: steady below freezing, no sun, no wind, no free water. The winters that kill lavender are the bare-ground ones with alternating thaw and freeze, so where snow is unreliable the boughs matter more.

Growing lavender in pots and overwintering them

A pot is the answer if you have clay, a balcony, or live in zone 3. It gives total control of drainage but removes the ground's insulation, so overwintering needs a plan.

Use at least 25–30 cm (10–12 in) across and 30 cm (12 in) deep, larger if you can, since more soil volume means more winter insulation. Terracotta dries evenly but cracks if it freezes wet; plastic handles frost better but dries slowly. Large drainage holes are non-negotiable. Use a lean mix: two parts potting or cactus compost, one part coarse sand, one part gravel, plus a pinch of lime. Water when it is dry 3 cm (1 in) down and empty the saucer.

Overwintering the pot

• Cool and frost free. An unheated garage, cold porch or root cellar at 0–7 °C (32–45 °F) with some light is safest. Water a splash once a month. This is the only sensible way to keep Spanish and French lavender.
• Outdoors against a south or west wall. Works for English lavender in zones 5–6. Lift the pot onto bricks so the holes never sit in ice, wrap it in burlap and lay boughs over the plant.

A heated room is worse. Lavender needs a cold rest, and at 20 °C (68 °F) in dry air it goes leggy and covered in spider mites. Toronto Master Gardeners advise a bright window and nights near 5 °C (40 °F) if you must bring one in.

Harvesting and drying lavender

Cut when the lowest florets on the spike have just opened and the rest are still closed buds. Oil content peaks then and the buds stay attached after drying. UC IPM puts it as harvesting with only a few florets open; wait for full bloom and the flowers shatter at a touch. Bloom runs in July for English lavender and late July into August for lavandin, later in zones 3–4.

Cut early in the morning once the dew has dried, taking the stem as low as you can without entering brown wood and leaving 5–10 cm (2–4 in) of green leaf, which doubles as the light trim the plant needs.

1. Bundle 50–100 stems, no more than 4 cm (11/2 in) thick at the base, and tie tightly since stems shrink as they dry.
2. Hang upside down somewhere dark, dry and airy; sun bleaches the colour in days.
3. Leave two to four weeks. Buds should feel hard and stems snap, not bend.

Store dried buds in a sealed jar in the dark, where the scent holds a year or two. For cooking use English lavender; lavandin carries more camphor and turns bitter.

Propagating lavender from cuttings

Lavender cannot be divided; a subshrub with a woody base dies if you cut it in pieces. Cuttings give free plants for a whole hedge. The RHS lists softwood or semi-ripe cuttings in early to midsummer and hardwood cuttings after flowering; in zones 3–5, August cuttings root more slowly but survive better.

1. Choose non-flowering side shoots 8–12 cm (3–5 in) long.
2. Pull the shoot downward so a heel of older bark comes with it, or cut below a leaf pair.
3. Strip the lower half of leaves, leaving four to six at the tip.
4. Insert 3–5 cm (1–2 in) deep into half coarse sand and half seed compost, several to a pot.
5. Water once and place in bright indirect light. Tent loosely with a bag if the air is dry, but vent daily.
6. Keep the mix barely moist; roots appear in three to eight weeks.

August cuttings are too small to plant out the same autumn; overwinter them cool and frost free and plant out in spring. Seed gives uneven plants and needs a month of cold stratification, the same method as other herbs in starting seeds indoors.

Lavender for bees and butterflies

Lavender is one of the most reliable nectar plants in a cold-climate garden, and it flowers in the July gap when much else is finished.

Here is a figure almost no growing guide mentions. The RHS reports a University of Sussex trial comparing thirteen cultivars across three species through the whole flowering season. Lavandin cultivars drew roughly four times as many pollinator visits as English lavender, and within the lavandins 'Gros Bleu' was more than twice as popular as 'Old English'. Flower colour made no difference.

For zones 3–6 that is a trade-off. In zone 5 or 6, plant a lavandin such as 'Grosso'. In zone 4 or colder, a hardy English lavender that lives ten years does more for bees than a lavandin that dies its second winter. Planting near fruit trees extends the season for the same insects, a point in the guide to growing apple trees. Leave part of the plant untrimmed into September.

Why lavender goes woody, and when to replace it

All lavenders go woody. It is not a disease, it is how the plant grows. A subshrub adds green growth at the top of last year's shoots and everything below turns to wood, so the green zone moves up each year. After five to eight years without pruning you have a bundle of grey brooms wearing a thin green hat.

What speeds it up: no annual pruning above all, plus nitrogen feeding, too little sun, and snow splaying open a flat-topped plant.

The RHS is honest about the end: even pruned annually, older lavender plants become straggly, very woody and misshapen, and are best replaced. A well-managed English lavender holds eight to fifteen years. The test is simple — if more than half the height is bare brown wood and bloom is thinner than last year, plan the replacement and take cuttings the previous August.

Zone table: lavender in USDA zones 3–7

The table is a starting point, not a promise. A raised gravel bed against a south wall behaves like a zone warmer, a clay hollow in shade like a zone colder. Zone 3 is prairie Canada, zone 4 much of Minnesota and southern Ontario, zone 5 upstate New York and the Scottish Highlands, zone 6 most of Britain.

Lavandin drops out roughly a zone earlier than English lavender, which is why species matters more than cultivar. The pruning window also moves about six weeks between zone 7 and zone 3, so a date copied from a British guide can be badly wrong in Minnesota.

Common mistakes

• Planting in bagged garden soil. Peat-based mixes hold water. Cut them with grit and coarse sand, or build a new bed.
• Buying Spanish or French lavender for the border. Rabbit-ear bracts mean a container and frost-free storage.
• Cutting into bare brown wood. Old stems carry no dormant buds. Leave 2–5 cm (1–2 in) of green per stem.
• Pruning in autumn. A late cut pushes soft growth and opens wounds before winter. Wait for spring.
• Feeding to get more flowers. Nitrogen gives soft shoots that winterkill.
• Mulching with bark or compost. Organic mulch traps moisture at the crown. Use gravel and leave the stem base bare.
• Packing winter cover with wet leaves. They mat into an airless lid. Use loose boughs and remove them in April.

Frequently asked questions

Will lavender survive a zone 4 winter?
English lavender will, in a raised gravel bed in full sun with evergreen boughs laid over it once the ground freezes. 'Munstead', 'Hidcote' and 'SuperBlue' are rated zone 4. Lavandin is marginal there and Spanish lavender is not hardy at all. Drainage decides the outcome more than temperature.

Why is my lavender dying?
Nine times out of ten it is root rot from winter wet, not frost. The soil holds water that cannot drain once the surface freezes, and the crown rots in early spring. Replant on a mound 20–30 cm (8–12 in) high with a third grit, swap bark mulch for gravel, and move it to the driest sunny spot you have.

When should you prune lavender?
In a cold climate, make the main cut in spring as soon as the first green shoots appear — late April in zone 6, mid to late May in zone 4. Take about a third of last year's growth and shape a low dome, staying above bare brown wood. After flowering, trim the spent stalks plus 2.5 cm (1 in) of leaf growth.

Can you cut lavender back into old wood?
No. Lavender carries no dormant buds in bare brown wood, so a cut there leaves a stub that never regrows. Leave 2–5 cm (1–2 in) of green with visible leaf buds on each stem. To rejuvenate a woody plant, work over three years, a third of the stems each year, cutting only to live growth.

What soil does lavender need?
Lean, gravelly, fast-draining soil at pH 6.5–7.5. A working mix is one third native mineral soil, one third coarse sand or grit, and one third angular gravel 8–16 mm (3/8–5/8 in). Avoid peat-based bagged soil, and never mix fine sand into clay — the result behaves like concrete.

How often should you water lavender?
Give 4–5 litres (1 gal) every two weeks through the first summer, more often in drought. In year two water only after three dry weeks. From year three an in-ground plant needs nothing in a normal summer. Containers are the exception: water when the mix is dry 3 cm (1 in) down.

How far apart should you plant lavender?
Space compact English cultivars 30 cm (12 in) apart for a hedge, three plants per metre. Larger cultivars go at 40–45 cm (16–18 in) and lavandins at 50–60 cm (20–24 in). Allow 90 cm (36 in) for a border specimen. Use a single row in zone 4 and colder, since a double row cuts airflow.

When do you harvest lavender for drying?
When the lowest florets on the spike have just opened and the rest are still buds, normally July for English lavender and late July into August for lavandin. That is when oil content peaks and buds stay on the stem. Cut in the morning after the dew dries, bundle no thicker than 4 cm (11/2 in), and hang upside down in the dark for two to four weeks.

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