GrowingHQ
Herbperennial herbStraightforward

Rosemary

Salvia rosmarinus

An evergreen Mediterranean shrub that becomes a permanent part of a garden rather than a seasonal crop, and one that is far more often killed by wet than by cold. Given sharp drainage and sun it needs almost nothing; in heavy damp ground it dies over winter, and growers conclude it was not hardy enough when the problem was the soil.

Position
Full sun
Water
low demand
Drainage
Free-draining
Grows to
100–150 cm × 100–150 cm
Hardiness
H4
Harvest
January to December
Difficulty
Straightforward

Described view

An established upright rosemary shrub with narrow dark needle-like leaves and pale blue flowers along the stems

August

Plant · Harvest

Rosemary’s year

Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.

ActivityJFMAMJJASOND
PlantApril. May. June. July. August.
In flowerApril. May. June.
HarvestJanuary. February. March. April. May. June. July. August. September. October. November. December.
PruneMay. June. July.

Names that cause confusion

Rosmarinus officinalis — The former botanical name, still in near-universal use on labels and in books. Rosemary was moved into Salvia on genetic evidence; the plant is unchanged.

Timing that travels

The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.

  • Plant0–16 weeks after your last spring frost
    source

    Sourced guidancehigh confidence

    • Royal Horticultural Society: Rosemary — planting

    Checked 2026-08-13

    Spring planting is safer than autumn in Britain: it gives the plant a full season to establish before facing winter wet.

  • Prune2–10 weeks after your last spring frost
    source

    Sourced guidancehigh confidence

    • Royal Horticultural Society: Rosemary — pruning

    Checked 2026-08-13

    After flowering. Never cut back into old bare wood, which does not reshoot.

What kind of herb this is

Herbs are a kitchen grouping rather than a botanical one, and the plants in it want opposite things. This is the one distinction that decides how to treat it.

Mediterranean woody herb

Growing regime
source

Sourced guidancehigh confidence

  • Royal Horticultural Society: Rosemary — growing

Checked 2026-08-13

Wants sun, poor free-draining ground and very little water once established. Far more of these die from winter wet at the roots than from cold air, so drainage matters more than hardiness ratings suggest.

Treated the same way: bay, borage, chamomile, hyssop, lemon thyme, marjoram and 7 more in the same group. The herb bed, split by regime

Why winter wet kills a Mediterranean herbTwo soil cross-sections side by side. On the left, a well-drained planting: the crown of a rosemary sits slightly proud of the surrounding soil on a low mound, the root zone is open gritty soil with air between the particles, and arrows show winter rain moving down and away past the roots. The plant above is dense and well furnished. On the right, the same herb in heavy soil in a hollow: the crown sits level with or below the surface, the root zone is dense soil over a compacted pan, and winter rain has nowhere to go so a water table stands in the root zone from November to March. The roots there are drawn broken and dashed to show they have died, and the plant above is sparse and thin. The point is that the plant looks unharmed all winter because an evergreen with a full canopy asks almost nothing of its roots in January, so the loss only shows the following spring when it fails to grow.Sharp drainagecrown proud, water moves throughroots stay firm and paleair between the particles all winterWinter wetcrown in a hollow, water standswater table, Nov–Marcompacted pan — nowhere to goroots dark, soft and sourand the plant above still looks fineopen gritty soilheavy soilstanding waterliving rootsPlanting on a low mound, adding grit, or standing a pot on feet all do the same job: get the crown above the water.
The damage happens in January and shows in May. An evergreen herb asks almost nothing of its roots in winter, so a drowned root system stays invisible until the plant is asked to grow and cannot.
Indoors
Not worth growing indoors
Where the indoor assessment comes from
IndoorsSourced guidancemoderate confidence
  • Royal Horticultural Society: Rosemary — growing indoors

Checked 2026-08-13

Almost any herb will sit on a windowsill in July. This is about whether it is still there in March, which is the part a pot on a supermarket shelf does not tell you.

What happens when it flowers

On a herb this is rarely a problem and rarely nothing. It is the point at which the plant stops being what you grew it for — by a lot, a little, or not at all.

No real effect on the leaves
source

Sourced guidancehigh confidence

  • Royal Horticultural Society: Rosemary — harvesting

Checked 2026-08-13

Nothing to do about it. Flowering does not change what rosemary is worth picking, so there is no reason to prevent it.

What it is worth to pollinators

Recorded only where the evidence is specific to this plant, because “good for bees” attached to everything means nothing attached to anything.

Nectar value
high
source

Sourced guidancemoderate confidence

  • Royal Horticultural Society: Plants for pollinators

Checked 2026-08-13

In flower
March, April, May

Picking it and feeding bees are not the same plan

Almost none in practice, and rosemary is unusual in that. Picking sprigs for the kitchen takes a fraction of a mature bush, and it flowers on wood you are unlikely to be cutting in spring.

Conditions it needs

Light
Full sun
Direct sun
6 hours a day or more
Frost
HardySourced guidanceDepends on conditions
Hardiness rating
H4 (RHS)
Grows best at
15–28 °C
Soil
Sandy, Chalky, Loam
Soil pH
6–8
Drainage
Free-draining
Water needs
low
Drought
good tolerance
Waterlogging
poor tolerance
Heat
good tolerance
Wind and exposure
good tolerance
Where these figures come from
LightSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — position

Checked 2026-08-13

Direct sunHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

FrostSourced guidanceDepends on conditionshigh confidence

Applies when: Hardy in free-draining soil. The same plant in cold wet ground is often lost over winter — it is a drainage problem presenting as a hardiness problem.

  • Royal Horticultural Society: Rosemary — hardiness

Checked 2026-08-13

Hardiness ratingSourced guidancehigh confidence
  • Royal Horticultural Society: RHS hardiness ratings

Checked 2026-08-13

Grows best atHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

SoilSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — soil

Checked 2026-08-13

Soil pHSourced guidancehigh confidence

One of the few culinary herbs entirely happy on chalk.

  • Plant Finder — Missouri Botanical Garden: Salvia rosmarinus

Checked 2026-08-13

DrainageSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — soil

Checked 2026-08-13

Water needsSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — watering

Checked 2026-08-13

DroughtSourced guidancehigh confidence
  • Royal Horticultural Society: Drought-tolerant plants

Checked 2026-08-13

WaterloggingSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — soil

Checked 2026-08-13

HeatSourced guidancehigh confidence
  • Plant Finder — Missouri Botanical Garden: Salvia rosmarinus

Checked 2026-08-13

Wind and exposureSourced guidancehigh confidence

Tolerates coastal wind and salt well.

  • Royal Horticultural Society: Plants for coastal gardens

Checked 2026-08-13

On your soil

Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.

SoilVerdictWhy
Heavy clayStruggles hereRosemary is not killed by cold in Britain nearly as often as it is killed by wet. Roots sitting in cold, saturated clay through winter rot, and the plant that looked healthy in October is dead in March. The pH and fertility of clay are entirely acceptable to it; the winter drainage is not.
SandyPrefers this soilSandy soil's low fertility and sharp drainage are exactly what rosemary wants, and it is one of very few crops genuinely improved by ground most growers apologise for.
Chalky and alkalinePrefers this soilSharp drainage and a high pH are the conditions rosemary evolved on, and chalky gardens grow it better than the loam everyone else is envious of. The same is true of thyme, sage and oregano — the group that is difficult everywhere else is easy here.
LoamPrefers this soilLoam suits Rosemary as it stands: The pH suits it: it wants 6 to 8, and this soil is in that range. The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering.
SiltyPrefers this soilSilty suits Rosemary as it stands: The pH suits it: it wants 6 to 8, and this soil is in that range. The free drainage is exactly what it wants. The soil holds moisture, which saves a great deal of watering.
Peaty and acidWorks, with one conditionRosemary will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. A plant that stays in the ground through winter with its roots in cold, saturated soil rots — which is what kills most of what fails on heavy ground, rather than the cold.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Shallow over rockPrefers this soilShallow over rock suits Rosemary as it stands: The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. It stands dry conditions better than most, which this soil will test.
Made ground and urban soilWorks, with one conditionRosemary will crop on made ground and urban soil, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. A plant that stays in the ground through winter with its roots in cold, saturated soil rots — which is what kills most of what fails on heavy ground, rather than the cold.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.

Not sure which you have? Four hand tests will settle it.

Space and spacing

Mature height
100–150 cmSourced guidanceDepends on conditions
Mature spread
100–150 cm
Rooting depth
60 cm
Spacing
90 cm apart
Where these figures come from
Mature heightSourced guidanceDepends on conditionshigh confidence

Applies when: Upright cultivars. Prostrate ones stay below 30 cm and trail over a wall or the edge of a raised bed.

  • Royal Horticultural Society: Rosemary — size

Checked 2026-08-13

Mature spreadHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Rooting depthHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

SpacingSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — spacing

Checked 2026-08-13

How far apart to plant rosemaryThree rosemary plants drawn in a row at their recorded spacing of 90 cm between plants. The spacing is drawn to scale against a one metre rule; the plants themselves are symbols rather than scale drawings, so the distance between them is the part to read.90 cmone metre
Measured centre to centre. Plants set closer than this compete for light and water long before they look crowded, and the crowding cannot be undone once they are in.

In a container

Minimum volume
15–20 litres
Minimum depth
30 cm
Where the container figures come from
Minimum volumeSourced guidancehigh confidence
  • Royal Horticultural Society: Herbs in containers

Checked 2026-08-13

Minimum depthHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

A container of gritty compost is the practical answer on clay, because it supplies the drainage the plant needs.

Value to wildlife

Recorded only where the evidence names a resource and the months it is available. Most plants flower; that on its own is not what this section is about.

Nectar
A significant source
In flower
Mar, Apr, May
Where these figures come from
NectarSourced guidancemoderate confidence
  • Royal Horticultural Society: Plants for pollinators

Checked 2026-08-13

What keeping this costs

Almost none in practice, and rosemary is unusual in that. Picking sprigs for the kitchen takes a fraction of a mature bush, and it flowers on wood you are unlikely to be cutting in spring.

Where and how you can grow it

Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.

MethodSuitabilityWhat it needs
Open groundWell suited
Sourced guidanceDepends on conditionshigh confidence

Applies when: On free-draining soil. On heavy clay it is marginal at best and usually short-lived.

  • Royal Horticultural Society: Rosemary

Checked 2026-08-13

Sharp drainage; Full sun
ContainerWell suited
source

Sourced guidancehigh confidence

  • Royal Horticultural Society: Herbs in containers

Checked 2026-08-13

Gritty free-draining compost; 15 litres or more; Sparing watering
Raised bedWell suited
source

Sourced guidancehigh confidence

  • Royal Horticultural Society: Mediterranean herbs

Checked 2026-08-13

A raised bed of gritty soil is the standard solution for Mediterranean herbs on wet ground.
Traditional dug bedWorkable
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Grit worked into the planting position
GreenhouseWorkable
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Chiefly for overwintering container plants in cold districts.
HydroponicsWorkable
source

GrowingHQ editorial positionmoderate confidence

Woody, slow, and prone to root rot in a wet medium. It is the least suitable of the Mediterranean herbs for a system and the one most often sold in kits.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

PolytunnelWorkable
source

Sourced guidancemoderate confidence

  • Agriculture and Horticulture Development Board — AHDB: Protected cropping

Checked 2026-08-13

WindowsillMarginal
source

GrowingHQ editorial positionmoderate confidence

Rosemary tolerates a sill for a season but resents the warm, still, dry indoor air over winter and usually declines. It is far better left outdoors, where it is hardy.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

Growing it

  • PlantingPlant into free-draining soil in full sun, working grit into heavy ground or planting on a slight mound. Winter wet at the roots kills more rosemary in Britain than cold does.
  • PruningTrim lightly after flowering, cutting only into growth that still carries leaves. Rosemary does not reshoot from bare old wood, so a hard cut into a leggy plant kills the branch.
  • PropagationTake semi-ripe cuttings in summer. Rosemary strikes readily, which is worth doing every few years because plants become woody and sparse with age.
  • WateringWater an established plant only in prolonged drought. Routine watering is the commonest mistake made with it.
  • FeedingDo not feed a rosemary in the ground. It evolved on thin limestone and a fed plant makes soft, sappy growth that tastes weaker, flops open in the middle and is the first to be damaged by frost. A plant in a pot is the one exception — container compost is exhausted after a season or two, so top-dress with fresh loam-based compost each spring and give a single balanced feed in April if growth has become obviously short and pale.
  • HarvestingPick sprigs at any time of year — this is one of the few herbs with nothing to wait for. Take them from the outside of the bush and from different sides each time, cutting into the current season's soft growth rather than the bare woody stems below it. Flavour is strongest just before flowering in spring, and a plant picked regularly through the summer stays denser than one left alone.
Where this guidance comes from
PlantingSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — soil

Checked 2026-08-13

PruningSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — pruning

Checked 2026-08-13

PropagationSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — propagation

Checked 2026-08-13

WateringSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — watering

Checked 2026-08-13

FeedingSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — feeding

Checked 2026-08-13

HarvestingSourced guidancehigh confidence
  • Royal Horticultural Society: Rosemary — harvesting

Checked 2026-08-13

Where to make a pruning cutFour stems compared. The first is cut cleanly on a slope about five millimetres above an outward-facing bud, sloping away from it, and is labelled correct. The second is cut too far above the bud, leaving a long stub that dies back. The third is cut too close, into the bud itself, which loses the shoot. The fourth is cut sloping towards the bud so rain runs onto it rather than away, which rots it. In every case the bud points outwards, away from the centre of the plant.Correct5 mm, sloping awayToo highstub dies backToo closebud lostSloping inrain sits on the bud
The bud you cut to becomes the new shoot, and it grows in the direction it points — which is why an outward-facing bud opens the plant up and an inward-facing one crosses the middle.
Four ways to make more plantsFour propagation operations compared, each showing where the separation is made and what must be present on both sides of it. Division: a clump cut between crowns, with roots and at least one growing point on every piece. Stem cutting: a shoot cut just below a leaf node, because the node is where roots form, with the lower leaves removed. Runner: a plantlet already rooting where it touches the ground, severed from the parent only after its own roots have taken. Offset: a young shoot at the base of the parent, separated with its own roots attached. In each case the cut is marked and the part that must be retained is labelled.Divisioncut between crownsroots on every piececut below a nodeStem cuttingroots form at the nodestrip the lower leavesRunnerlet it root firstthen sever the linkOffseta shoot at the basetake its roots with it
The rule is the same in all four: the new piece needs both a growing point and roots of its own. A cutting is the exception that has to make its roots afterwards, which is why the node matters so much.

Is it worth putting under cover?

Whether it will grow there is on the methods table above. This is whether the space is well spent, which is a different question and usually the one being asked.

StructureWhat protection is worthWhat decides it
GreenhouseWorse under cover
source

GrowingHQ editorial positionmoderate confidence

What protection is worth for this crop, judged against the same standard as every other record in this file.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

Winter humidity. Rosemary is hardy in most of Britain and is killed by still damp air far more often than by cold.
PolytunnelWorse under cover
source

GrowingHQ editorial positionmoderate confidence

What protection is worth for this crop, judged against the same standard as every other record in this file.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

Winter humidity, worse under polythene.

On a windowsill

Spring to autumn
source

GrowingHQ editorial positionmoderate confidence

How long the crop is actually productive on an ordinary British windowsill without added light.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

 Productive from roughly March to October and not after. Growth stops when the light does, and a plant pushed through the dark months usually does not recover. Light and airflow. A bright sill suits it in summer; indoors over winter it drops needles and develops powdery mildew on the shaded side.

Growing it without soil

Nearly anything can be grown in a soilless system by somebody with enough equipment. The useful question is whether it is worth it, in which technique, and what goes wrong.

Works with conditions

Succeeds when the conditions listed here are met and fails when they are not. The conditions are the answer, not a caveat.

source

GrowingHQ editorial positionmoderate confidence

Woody, slow, and prone to root rot in a wet medium. It is the least suitable of the Mediterranean herbs for a system and the one most often sold in kits.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

Techniques that suit it

  • Drip-fed mediumSolution is dripped into an inert medium around each plant. The most forgiving technique and the one that suits large, long-season, heavy crops.
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Root space
Moderate and free-draining; it becomes a shrub in time.
Lighting
Needs supplementary light
pH band
5.5–6.5
Where these figures come from
Root spaceHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

LightingHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

pH bandSourced guidancehigh confidence

Outside roughly this band, individual nutrients become unavailable even when they are present in the solution — which is why a crop can starve in a full reservoir.

  • Purdue Extension — Purdue University: Hydroponic solution management — pH

Checked 2026-08-13

What actually goes wrong

  • Warm solution. Above roughly 22 °C the water holds much less dissolved oxygen and root disease follows quickly, which is why summer is harder than winter in an indoor system.
    source

    Sourced guidancemoderate confidence

    • Purdue Extension — Purdue University: Solution temperature and dissolved oxygen

    Checked 2026-08-13

  • Pump or power failure. In nutrient film and aeroponics there is no reserve at the roots, so a crop can be lost within hours; medium-based systems hold moisture and are far more forgiving.
    source

    Sourced guidancehigh confidence

    • Purdue Extension — Purdue University: Hydroponic system design — failure modes

    Checked 2026-08-13

No nutrient recipes here

GrowingHQ records pH bands, which are measurable properties of nutrient availability, and deliberately records no EC or PPM targets and no mixing instructions. Published targets vary by cultivar, growth stage, water source and technique, and the figures that apply to your system are on the product you bought.

Harvesting

  • When it is readyPick sprigs at any time of year; flavour is strongest before flowering.
  • How to pick itCut short sprigs from the tips of shoots, never into bare wood.
  • Keeping itDries well and keeps its flavour, unlike most soft-leaved herbs.
Where the harvest guidance comes from
When it is readyHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

How to pick itHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Keeping itHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

What goes wrong

ProblemHow oftenNotes
Spittlebugcommon
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Rosemary beetlecommon
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Feeds through autumn and winter, when the damage is usually blamed on cold.

Grown with, grown after, grown instead

Every relationship states its mechanism. A pairing nobody can explain is a pairing nobody has checked, and it does not go in.

  • Closely relatedSage
    Both are Salvia species — rosemary was reclassified into the genus on genetic evidence — and both want the same sharp drainage, full sun and light pruning. Guidance transfers between them almost unchanged.
    source

    Sourced guidancehigh confidence

    • Plants of the World Online — Royal Botanic Gardens, Kew: Salvia rosmarinus

    Checked 2026-08-13

  • Grown togetherThyme
    Both Mediterranean sub-shrubs wanting poor, sharply drained soil, full sun and very little water, so they can share one bed watered as a unit. The benefit is compatible requirements rather than any interaction between the plants.
    Sourced guidanceDepends on conditionshigh confidence

    Applies when: A shared-conditions grouping, not a pest or growth interaction.

    • Royal Horticultural Society: Mediterranean herbs

    Checked 2026-08-13

Sources for this page

Agriculture and Horticulture Development Board · GrowingHQ editorial synthesis · Plant Finder · Royal Horticultural Society

Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-13.

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