Vegetablesalad leafStraightforward

Lettuce

Lactuca sativa

Fast, shallow-rooted and productive in almost any container, which makes lettuce the crop most worth growing where space is short. Two things govern it. Sown as loose-leaf and cut repeatedly it yields far more from the same area than hearting types do. And it bolts — in heat, in long days, and after any check to growth — so the answer is always a small sowing every fortnight rather than one large one.

Position: Full sun or Partial shade
Water: moderate demand
Drainage: Moisture-retentive
Grows to: 15–30 cm × 20–30 cm
Hardiness: H4
Harvest: May to October
Difficulty: Straightforward

Described view

A dense patch of loose-leaf lettuce being cut with scissors a few centimetres above the crowns, leaving the growing points intact

August

Sow outdoors · Harvest

Coming next month: sow under cover.

Lettuce’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.

Activity	F	M	A	M	J	J	A	S	O
Sow under cover	February.	March.						September.	October.
Sow outdoors		March.	April.	May.	June.	July.	August.	September.
Harvest				May.	June.	July.	August.	September.	October.

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.

Sow outdoors
0–24 weeks after the soil becoming workable, every two weeks — a short row at a time
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Lettuce — successional sowing
Checked 2026-08-13

Conditions it needs

Light: Full sun, Partial shade
Direct sun: 4 hours a day or more
Frost: HardySourced guidanceDepends on conditions
Hardiness rating: H4 (RHS)
Grows best at: 10–20 °C
Germinates at: 4–25 °C
Soil: Loam, Peat-free compost, Silt
Soil pH: 6–7
Drainage: Moisture-retentive
Water needs: moderate
Drought: poor tolerance
Waterlogging: poor tolerance
Heat: poor tolerance
Wind and exposure: moderate tolerance

Where these figures come from

LightSourced guidancehigh confidence

Genuinely prefers partial shade in midsummer, when full sun brings on bolting.

Royal Horticultural Society: Lettuce — 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: Winter-hardy cultivars stand frost under cover or a cloche; summer cultivars are damaged by it.

Royal Horticultural Society: Lettuce — hardiness

Checked 2026-08-13

Hardiness ratingSourced guidancehigh confidence

Royal Horticultural Society: RHS hardiness ratings

Checked 2026-08-13

Grows best atHorticultural consensusmoderate confidence

University of Minnesota Extension — University of Minnesota: Growing lettuce

Checked 2026-08-13

Germinates atSourced guidancehigh confidence

Lettuce seed enters thermodormancy above roughly 25 °C and simply will not germinate — which is why midsummer sowings fail and why sowing in the evening, or in a cooler spot, fixes them.

OSU Extension Service — Oregon State University: Vegetable seed germination temperatures

Checked 2026-08-13

SoilHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Soil pHSourced guidancehigh confidence

University of Minnesota Extension — University of Minnesota: Soil pH for vegetable crops

Checked 2026-08-13

DrainageHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Water needsHorticultural consensusmoderate confidence

Shallow-rooted, so it needs little water at a time but needs it often.

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

Home and Garden Information Center — Clemson Cooperative Extension: Lettuce — culture

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.

Soil	Verdict	Why
Heavy clay	Works, with one condition	Lettuce will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.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.
Sandy	Works, with one condition	Lettuce is shallow-rooted and has almost no drought tolerance, and a sandy soil delivers the check that makes it bolt faster than any other. It is not a difficult crop here — it is a crop that cannot be left.Water regularly and mulch, and sow little and often rather than all at once so a lost batch costs a fortnight instead of a season.
Chalky and alkaline	Struggles here	Lettuce 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.
Loam	Prefers this soil	Loam suits Lettuce 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. There is ample rooting depth for it.
Silty	Prefers this soil	Silty suits Lettuce as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. Silt is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering. There is ample rooting depth for it.
Peaty and acid	Works, with one condition	Lettuce 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. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.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 rock	Works, with one condition	Lettuce 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 soil	Works, with one condition	Lettuce 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. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.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: 15–30 cm
Mature spread: 20–30 cm
Rooting depth: 15–20 cm
Spacing: 15–30 cm apartSourced guidanceDepends on conditions
Row spacing: 30 cm

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 depthSourced guidancehigh confidence

The shallowest rooting of any crop in this catalogue apart from radish — which is why a 15 cm trough is enough.

Royal Horticultural Society: Lettuce — growing

Checked 2026-08-13

SpacingSourced guidanceDepends on conditionshigh confidence

Applies when: About 15 cm for loose-leaf and small cos, up to 30 cm for large hearting types. Cut-and-come-again leaf can be sown far denser and never thinned.

Royal Horticultural Society: Lettuce — spacing

Checked 2026-08-13

Row spacingSourced guidancehigh confidence

Royal Horticultural Society: Lettuce — spacing

Checked 2026-08-13

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: 5–10 litres
Minimum depth: 15 cm

Where the container figures come from

Minimum volumeSourced guidancehigh confidence: Royal Horticultural Society: Lettuce in containers
Checked 2026-08-13
Minimum depthSourced guidancehigh confidence: Royal Horticultural Society: Salad crops in containers
Checked 2026-08-13

Excellent in shallow containers and windowboxes, and easier to protect from slugs than a bed. Cut-and-come-again varieties give the longest return from one sowing.

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.

Method	Suitability	What it needs
Open ground	Well suited source Sourced guidancehigh confidence Royal Horticultural Society: Lettuce Checked 2026-08-13
Traditional dug bed	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Raised bed	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Container	Well suited source Sourced guidancehigh confidence Royal Horticultural Society: Lettuce in containers Checked 2026-08-13	15 cm of depth is enough; Watering little and often
Windowsill	Well suited source Sourced guidancehigh confidence Royal Horticultural Society: Salad leaves indoors Checked 2026-08-13	A bright sill; Cutting as baby leaves rather than growing to a heartCut-and-come-again leaf on a sill is one of the few indoor edibles that produces a genuinely useful quantity.
Hydroponics	Well suited source Sourced guidancehigh confidence Purdue Extension — Purdue University: Hydroponic leafy greens Checked 2026-08-13	The archetypal hydroponic crop: fast, shallow-rooted, entirely leaf, and grown this way commercially at enormous scale.
Vertical growing	Well suited source Horticultural consensusmoderate confidence Small, shallow-rooted and shade-tolerant — the combination that makes stacked planting work. No external citation — see the evidence type above. Checked 2026-08-13
Polytunnel	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13	Extends the season to nearly year-round.
Greenhouse	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Cold frame	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13	The classic use of a cold frame: winter salad.
Aquaponics	Well suited source Sourced guidancehigh confidence Purdue Extension — Purdue University: Aquaponic leafy greens Checked 2026-08-13

Growing it

SowingSow thinly about 1 cm deep. In hot weather sow in the evening or in a shaded spot: lettuce seed refuses to germinate above roughly 25 °C, and a midsummer sowing that never appears has usually met that limit rather than failed for any other reason.1 cm
WateringWater little and often. A check from drying out brings bolting forward and makes the leaves bitter.
HarvestingFor loose-leaf types, cut the whole plant about 3 cm above the growing point rather than pulling it, and it will regrow for two or three further cuts.
FeedingLettuce grown in soil with compost worked in rarely needs feeding at all. In containers, or for repeated cut-and-come-again sowings, a dilute liquid feed after each cut keeps the leaves tender — hungry lettuce turns bitter and runs to seed.

Where this guidance comes from

SowingSourced guidancehigh confidence: OSU Extension Service — Oregon State University: Lettuce seed germination
Checked 2026-08-13
WateringHorticultural consensusmoderate confidence: Royal Horticultural Society: Lettuce — watering
Checked 2026-08-13
HarvestingSourced guidancehigh confidence: Royal Horticultural Society: Cut-and-come-again salad leaves
Checked 2026-08-13
FeedingSourced guidancemoderate confidence: Royal Horticultural Society: Lettuce — cultivation
Checked 2026-08-13

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.

Structure	What protection is worth	What decides it
Greenhouse	Extends 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	Winter light. Lettuce is the crop that makes a greenhouse useful in November, and the crop most obviously wasting it in July.
Polytunnel	Extends 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	Winter light, in the structure that does it most cheaply.

On a windowsill

A few weeks, then replace

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

A supermarket pot or a sowing gives a few weeks of cutting and is then exhausted. That is what the crop is, not a failure to keep it alive. Light and root volume. A sowing gives cut-and-come-again leaves for a few weeks; a hearted lettuce needs more light than an indoor sill has.

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.

Well suited

An established soilless crop. Grown this way commercially or routinely by home growers, with predictable results.

source

Sourced guidancehigh confidence

Purdue Extension — Purdue University: Hydroponic leafy greens

Checked 2026-08-13

The archetypal soilless crop: fast, shallow-rooted, entirely leaf, and harvested before most problems have time to develop.

Techniques that suit it

Nutrient film (NFT)A shallow stream of solution runs over bare roots in a sloped channel. Cheap and productive for small fast crops; a pump failure kills a crop within hours because there is no reservoir at the roots.
Deep water cultureRoots hang in aerated solution. Very productive and very unforgiving of solution temperature — warm solution holds less oxygen and root disease follows.
Kratky (non-circulating)A sealed reservoir whose level falls as the plant drinks, leaving an air gap for the roots. No pump, no power, and no way to correct the solution once it is running.
Ebb and flowA bed of inert medium floods and drains on a timer. The medium holds moisture between floods, which makes it far more tolerant of interruption than NFT.

source

Sourced guidancehigh confidence

Purdue Extension — Purdue University: Technique selection for leafy crops

Checked 2026-08-13

Root space: Small and shallow. Lettuce is the crop nutrient film was designed around, and a channel a few centimetres deep is enough.
Lighting: Needs supplementary lightHorticultural consensusDepends on conditions
Solution temperature: 18–22 °C
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 consensusDepends on conditionsmoderate confidence

Applies when: A bright conservatory or windowsill will grow leaf in summer; winter production needs lamps.

No external citation — see the evidence type above.

Checked 2026-08-13

Solution temperatureSourced guidancemoderate confidence

Purdue Extension — Purdue University: Solution temperature and dissolved oxygen

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

Bolting. Warm indoor conditions and long lit days push lettuce into flower quickly, which is a control problem rather than a nutrition one.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Bolting
Checked 2026-08-13
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

Time from sowing or planting: 6–12 weeks

Sourced guidanceDepends on conditionshigh confidence

Applies when: Six weeks for baby leaves, up to twelve for a full heart.

Royal Horticultural Society: Lettuce — timing

Checked 2026-08-13

When it is readyLoose-leaf types are usable from baby-leaf size onwards. Hearting types are ready when the heart feels firm; left beyond that they bolt.
How to pick itCut with scissors or a knife above the growing point for a repeat crop, or lift the whole plant for a heart.
Keeping itA few days in a refrigerator; better cut as needed.

Where the harvest guidance comes from

When it is readyHorticultural consensusmoderate confidence: Royal Horticultural Society: Lettuce — harvesting
Checked 2026-08-13
How to pick itSourced guidancehigh confidence: Royal Horticultural Society: Lettuce — harvesting
Checked 2026-08-13
Keeping itHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

Keep picking

Regular picking keeps this plant producing. Fruit or leaves left to mature signal it to slow down or stop.

What goes wrong

Problem	How often	Notes
Slugs and snails	common source Sourced guidancehigh confidence Royal Horticultural Society: Slugs and snails Checked 2026-08-13	The single biggest cause of failure in outdoor lettuce, and the reason module-raised transplants beat direct sowing.
Bolting	common source Sourced guidancehigh confidence Royal Horticultural Society: Bolting Checked 2026-08-13
Aphids	occasional source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Damping off	occasional source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13

Start from what you can see

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.

Follows on fromRadish
Radishes clear the ground in four to six weeks and lettuce takes eight to twelve, so alternating them in the same bed keeps a salad area in continuous production.
source
Horticultural consensusmoderate confidence
Royal Horticultural Society: Intercropping and catch cropping
Checked 2026-08-13
Alternative toSpinach
Both are quick shallow-rooted leaf crops that suit the same containers and systems, but they bolt under different conditions — spinach in long days, lettuce mostly in heat — so alternating them extends the salad season at both ends.
source
Sourced guidancehigh confidence
Royal Horticultural Society: Salad leaves
Checked 2026-08-13

Sources for this page

Home and Garden Information Center · OSU Extension Service · Purdue Extension · Royal Horticultural Society · University of Minnesota Extension

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.

If something is wrong with it

Holes eaten in leaves — 2 causes GrowingHQ holds for lettuce
Plant running up to flower before it is ready to eat — 2 causes GrowingHQ holds for lettuce

Something else? Work through it with the diagnostic tool.