GrowingHQ
VegetablerootDemanding

Celeriac

Apium graveolens var. rapaceum

A knobbly swollen stem base with celery's flavour and none of its stringiness, occupying the ground for a full season. Like celery it is a water-hungry bog plant, and the difference between a tennis ball and a football is almost entirely how consistently it was watered from midsummer onwards.

Position
Full sun or Partial shade
Water
high demand
Drainage
Moisture-retentive, Tolerates wet ground
Grows to
30–45 cm × 30–40 cm
Hardiness
H4
Harvest
October to December
Difficulty
Demanding

August

Nothing to do

No sowing, planting, harvesting or pruning window falls in August.

Celeriac’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
Sow under coverFebruary. March. April.
Plant outMay.
HarvestOctober. November. December.

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.

  • Plant out2–5 weeks after your last spring frost
    source

    Sourced guidancehigh confidence

    • Royal Horticultural Society: Celeriac — plant out

    Checked 2026-08-13

    Plant shallowly. The crown should sit on the surface, not be buried — burying it produces a small root and a lot of leaf.

Conditions it needs

Light
Full sun, Partial shade
Frost
Hardy
Hardiness rating
H4 (RHS)
Grows best at
15–21 °C
Germinates at
15–21 °C
Soil
Loam, Clay
Soil pH
6–7
Drainage
Moisture-retentive, Tolerates wet ground
Water needs
high
Drought
poor tolerance
Waterlogging
good tolerance
Heat
poor tolerance
Wind and exposure
moderate tolerance
Where these figures come from
LightSourced guidancemoderate confidence
  • Royal Horticultural Society: Celeriac — position

Checked 2026-08-13

FrostSourced guidancehigh confidence
  • Royal Horticultural Society: Celeriac — hardiness

Checked 2026-08-13

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

Checked 2026-08-13

Grows best atSourced guidancemoderate confidence
  • Royal Horticultural Society: Celeriac — temperature

Checked 2026-08-13

Germinates atSourced guidancemoderate confidence
  • Royal Horticultural Society: Seed germination temperatures

Checked 2026-08-13

SoilSourced guidancemoderate confidence
  • Royal Horticultural Society: Celeriac — soil

Checked 2026-08-13

Soil pHSourced guidancemoderate confidence
  • Plant Finder — Missouri Botanical Garden: Apium graveolens — culture

Checked 2026-08-13

DrainageSourced guidancemoderate confidence
  • Royal Horticultural Society: Celeriac — soil

Checked 2026-08-13

Water needsHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

DroughtHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

WaterloggingHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

HeatHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Wind and exposureHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

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 clayPrefers this soilHeavy clay suits Celeriac as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. It tolerates ground that stays wet, which most crops do not. Clay is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering.
SandyWorks, with one conditionCeleriac will crop on sandy, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure.
Chalky and alkalineStruggles hereCeleriac struggles on chalky and alkaline: The soil is substantially too alkaline for it: it wants pH 6 to 7, and this soil sits around 7.8 to 8.5. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering. A container or a raised bed of imported soil sidesteps the problem entirely.
LoamPrefers this soilLoam suits Celeriac as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering.
SiltyGrows well hereCeleriac grows perfectly well on silty without special measures, though it is not the soil it would choose.
Peaty and acidGrows well hereCeleriac grows perfectly well on peaty and acid without special measures, though it is not the soil it would choose.
Shallow over rockWorks, with one conditionCeleriac will crop on shallow over rock, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure.
Made ground and urban soilGrows well hereCeleriac grows perfectly well on made ground and urban soil without special measures, though it is not the soil it would choose.

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

Space and spacing

Mature height
30–45 cm
Mature spread
30–40 cm
Rooting depth
30 cm
Spacing
30–38 cm apart
Where these figures come from
Mature heightHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

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 guidancemoderate confidence
  • Royal Horticultural Society: Celeriac — spacing

Checked 2026-08-13

How far apart to plant celeriacThree celeriac plants drawn in a row at their recorded spacing of 30–38 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.30–38 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.

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 groundWorkable
source

Sourced guidancemoderate confidence

  • Royal Horticultural Society: Growing method suitability

Checked 2026-08-13

Traditional dug bedWorkable
source

Sourced guidancemoderate confidence

  • Royal Horticultural Society: Growing method suitability

Checked 2026-08-13

Raised bedWorkable
source

Sourced guidancemoderate confidence

  • Royal Horticultural Society: Growing method suitability

Checked 2026-08-13

GreenhouseWorkable
source

Sourced guidancemoderate confidence

  • Agriculture and Horticulture Development Board — AHDB: Celeriac — season length

Checked 2026-08-13

PolytunnelWorkable
source

Sourced guidancemoderate confidence

  • Agriculture and Horticulture Development Board — AHDB: Celeriac — season length

Checked 2026-08-13

ContainerMarginal
source

Sourced guidancemoderate confidence

  • Royal Horticultural Society: Growing method suitability

Checked 2026-08-13

HydroponicsMarginal
source

GrowingHQ editorial positionmoderate confidence

Most of a year in the system for one root. Celeriac is among the slowest crops in the catalogue and among the least suited to paying rent on lit space.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

Growing it

  • PruningRemove the lower outer leaves and any side shoots from midsummer, so the crown is exposed and swells rather than producing more foliage.
  • WateringWater generously and never let it dry out from midsummer onwards. The difference between a tennis ball and a football is almost entirely water during August and September.
  • MulchingMulch thickly around the plants in midsummer. It holds the moisture celeriac needs and saves a great deal of watering on light soil.
Where this guidance comes from
PruningSourced guidancehigh confidence
  • Royal Horticultural Society: Celeriac — care

Checked 2026-08-13

WateringSourced guidancehigh confidence
  • Royal Horticultural Society: Celeriac — care

Checked 2026-08-13

MulchingSourced guidancehigh confidence
  • Royal Horticultural Society: Celeriac — care

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.

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
GreenhouseExtends the season
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

Season length. Celeriac needs most of a British year to make a usable root, and starting it under cover is what makes that possible in the north.The protection is worth having at the START of the season rather than the end. A mature plant is entirely hardy and belongs outside.
PolytunnelExtends the season
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

Season length, addressed the same way.

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.

Not worth it

It can be made to grow, but a soilless system is the wrong tool — usually because of rooting volume, running cost, or a result no better than a pot of compost.

source

GrowingHQ editorial positionmoderate confidence

Most of a year in the system for one root. Celeriac is among the slowest crops in the catalogue and among the least suited to paying rent on lit space.

  • GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

The knobbly root is also mostly waste once peeled, which makes the yield per system-month worse than it first looks.

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.
Horticultural consensusDepends on conditionsmoderate confidence

Applies when: Medium beds only.

No external citation — see the evidence type above.

Checked 2026-08-13

Root space
Substantial, and held for the whole season.
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

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

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 readyLift from October once the root is 8–12 cm across. It will stand light frost in the ground; heavy frost damages the exposed crown, so mulch or lift.
  • How to pick itLift with a fork inserted well clear of the root, since the swollen part sits mostly above ground with the true roots below it. Cut the leaves off close to the crown and trim the whiskery roots away. Handle carefully — a bruised or gashed celeriac rots in store where a sound one keeps for months.
  • Keeping itSeveral months in a cool shed in boxes of sand, or a few weeks in a fridge.
Where the harvest guidance comes from
When it is readySourced guidancehigh confidence
  • Royal Horticultural Society: Celeriac — harvesting

Checked 2026-08-13

How to pick itSourced guidancehigh confidence
  • Royal Horticultural Society: Celeriac — harvesting

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
Celery leaf spotcommon
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

The same seed-borne fungus as on celery, and the same answer: buy treated seed.
Boron deficiencyoccasional
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Cracked stem and blackened young heart leaves on light or over-limed ground.
Slugs and snailscommon
source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

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 2026-08-14.