Growing Chives in a Greenhouse

What Research Actually Supports About Light, CO₂, Regrowth, Water, Temperature and Leaf Quality

Chives (Allium schoenoprasum L.) are perennial culinary herbs grown primarily for their hollow green leaves.

They tolerate repeated cutting and can remain productive for a long period, which makes them look like a simple greenhouse crop.

But chives have a more complicated environmental response than a generic “leafy herb.”

Published research shows important effects from:

Daily Light Integral
supplemental-light spectrum
photoperiod
seasonal rest / dormancy
temperature
CO₂
planting density
harvest schedule
root-zone salinity
postharvest temperature

There is no scientifically established stage-by-stage PAR, CO₂ and VPD recipe that guarantees:

tender leaves
fast regrowth
dark green color
stronger flavor
minimum yellowing
maximum shelf life

The better greenhouse strategy is to measure the actual environment and connect those measurements with crop yield, regrowth and quality.

Quick Reference

Variable	What It Tells You	What Chive Research Supports
PPFD / PAR	Photosynthetic light reaching the crop now	Supplemental light can greatly increase greenhouse chive biomass, but spectrum also matters
DLI	Total photosynthetic photons received during the day	A commercial greenhouse trial averaged ~8.5 DLI from natural light and added 6.05 DLI with supplemental lighting
Spectrum	Distribution of wavelengths	20% blue / 80% red LED produced 37% more fresh weight than HPS in one commercial greenhouse trial
Photoperiod	Length of the light period	Short days around a critical ~14 h can participate in chive rest-period induction under suitable temperatures
CO₂	Carbon available for photosynthesis	Direct Allium research including common chives compared ~400 vs 1200 ppm; elevated CO₂ increased biomass overall
VPD	Atmospheric evaporative demand	Useful for understanding crop water demand; no validated chive stage-specific VPD optimum exists
Root-zone salinity	Osmotic and ionic root stress	Direct research classified chives as salt-sensitive
Harvest schedule	Frequency of cutting	Direct research successfully used repeated 7- and 14-day harvest schedules; regrowth is not controlled by VPD alone
Temperature	Influences active growth and seasonal rest	Forcing research found 22–24°C produced the highest growth rates under its experimental conditions
Storage temperature	Postharvest environment	Fresh chive quality was maintained much longer at 0°C than at warmer storage temperatures

These are research references, not universal greenhouse specifications.

1. Chives Are a Perennial Cut-and-Regrow Crop

Unlike basil or cilantro, common chives can remain as perennial clumps.

Their underground structures support:

new leaf production
tillering
regrowth after cutting
seasonal rest and renewed growth

This makes repeated-harvest physiology especially important.

The environment needed to establish a young seedling is not necessarily identical to the environment affecting a mature repeatedly harvested clump.

2. Common Chives Are Not Garlic Chives

Common chives are:

Allium schoenoprasum.

Garlic chives are:

Allium tuberosum.

They differ in:

leaf shape
flavor
growth habit
flowering
physiology

Therefore, garlic-chive research should not automatically be used to create common-chive PAR or CO₂ targets.

This article focuses on:

Allium schoenoprasum.

3. PAR and DLI Answer Different Questions

PPFD measures photosynthetic photon flux at one moment.

It is expressed as:

µmol/m²/s.

It answers:

How much photosynthetic light is reaching the chive leaves right now?

DLI integrates those photons across the whole day.

It is expressed as:

mol/m²/day.

It answers:

How much photosynthetic light did the crop receive today?

For constant artificial lighting:

DLI = PPFD × light-hours × 0.0036

For example:

100 PPFD × 16 h
≈ 5.8 DLI

150 PPFD × 16 h
≈ 8.6 DLI

200 PPFD × 16 h
≈ 11.5 DLI

250 PPFD × 16 h
≈ 14.4 DLI

But greenhouse sunlight is not constant.

That is why DLI logging is particularly useful for chives grown through changing seasons.

4. Chives Have Direct Commercial-Greenhouse Supplemental-Light Evidence

A University of Tennessee study grew:

Allium schoenoprasum

hydroponically in a commercial greenhouse.

Researchers compared:

natural sunlight
natural sunlight + HPS
natural sunlight + LED with 20% blue / 80% red
natural sunlight + LED containing blue, green, red and far-red

Each supplemental-light treatment provided approximately:

70 µmol/m²/s

above natural sunlight.

5. Natural Greenhouse DLI Averaged About 8.5

During the production period, natural greenhouse DLI averaged approximately:

8.5 mol/m²/day.

But individual conditions ranged approximately from:

4 to 18 mol/m²/day.

That variation is important.

A greenhouse does not provide one fixed amount of light every day.

6. Supplemental Lighting Added About 6.05 DLI

Each supplemental-light treatment contributed approximately:

6.05 mol/m²/day

in addition to the greenhouse light.

Using the reported average natural DLI, that corresponds to an average combined daily photon exposure around:

14.6 mol/m²/day

during the trial.

This is a useful commercial-greenhouse research environment.

It is not proof that:

14.6 DLI is the universal chive optimum.

7. Supplemental Lighting Approximately Doubled Biomass

All three supplemental-light treatments produced approximately:

2× the shoot fresh weight

and:

2× the shoot dry weight

of the natural-sunlight-only treatment.

This is strong direct evidence that chives can become:

light-limited under greenhouse conditions.

8. But Photon Quantity Was Not the Whole Story

All supplemental treatments supplied approximately the same additional PPFD.

Yet they did not produce identical crops.

The:

20% blue / 80% red LED

treatment produced approximately:

37% greater shoot fresh weight

than the HPS treatment.

That means:

spectrum mattered even when supplemental photon quantity was similar.

9. The Same Red-Blue Treatment Also Increased Carotenoids

Total carotenoid content under:

20% blue / 80% red LED

was approximately:

20% higher

than under natural sunlight alone.

The other supplemental-light treatments did not show the same significant carotenoid increase.

Again:

maximum light quantity does not fully predict crop quality.

10. This Is One of the Best Reasons to Measure DLI but Record Spectrum Separately

A PAR meter tells us photon quantity.

It does not describe:

blue fraction
red fraction
green light
far-red

Two fixtures can provide similar PPFD while creating different:

morphology
fresh biomass
pigments

in chives.

11. The Researchers Explicitly Said the Precise Optimum Was Still Unknown

Importantly, the authors concluded that further work was needed to determine:

the precise quantity and quality of light needed to maximize chive yield and quality.

That statement should shape AquaHorti’s wording.

The study supports:

supplemental light works.

It does not support:

“250–400 PPFD is the proven chive optimum.”

12. A Useful Chive DLI Reference

The commercial greenhouse trial provides a particularly defensible comparison.

Natural greenhouse light

Average:

~8.5 DLI

Range:

~4–18 DLI

Supplemental contribution

+6.05 DLI

Approximate average combined environment

~14.6 DLI

The supplemental treatments greatly increased biomass.

Therefore, a crop receiving only low-single-digit DLI during dark seasons may reasonably be investigated for:

light limitation.

But current evidence does not justify one universal DLI target.

13. Do Not Convert the Study Into a Stage Table

The study did not prove:

seedling DLI = 4–6
early growth = 6–10
main growth = 10–14
preharvest = 8–12

Those numbers appeared in the old AquaHorti article without a corresponding controlled stage-response experiment.

They should be removed.

14. Photoperiod Has a Completely Different Role in Chives

Because chives are perennial, photoperiod does more than determine DLI.

It can also influence:

seasonal growth state and rest-period induction.

Classic controlled-environment research found a critical day length around:

14 hours

for rest-period induction under appropriate temperatures.

15. Short Days Can Help Induce a Rest Period

Chive rest-period research found that under medium temperatures:

short days promoted rest induction.

The approximate critical photoperiod was:

14 hours.

Long days could be used to help keep plants actively growing during periods when short days would otherwise favor rest.

This is highly relevant to autumn and winter greenhouse forcing.

16. Photoperiod and DLI Therefore Must Not Be Treated as the Same Variable

A 16-hour day can affect chives in two ways:

it changes the time available to accumulate photons
it changes the photoperiodic signal perceived by the plant

So the statement:

“Chives need 16 hours because they need more DLI”

would be incomplete.

The photoperiod itself can influence perennial growth behavior.

17. Temperature Also Participates in Rest Induction

The classic experiments found rest induction occurred over approximately:

>6°C to <20°C

with the strongest induction near:

14°C

under their experimental system.

Low temperature below about:

6°C

could preserve or even promote plant activity rather than inducing the same response.

This demonstrates that chive seasonal behavior is not controlled by photoperiod alone.

18. Rest Induction Took Weeks — Not Hours

Partial rest induction required approximately:

4 weeks

while full induction required approximately:

8 weeks

under the studied conditions.

That is another useful lesson.

Short-term fluctuations in greenhouse VPD cannot reasonably explain a seasonal developmental transition that develops across weeks.

19. Rest Can Be Useful for Forcing High-Quality New Leaves

The follow-up research found that a preceding rest period supported successful chive forcing.

During rest:

assimilates were redistributed
old leaves died
new undamaged foliage later developed

This shows why commercial perennial chive management can be different from simply keeping plants in uninterrupted maximum growth.

20. Forcing Temperature Has Direct Chive Evidence

Once chives were being forced into active growth, temperatures around:

22–24°C

produced the highest growth rates in the classic forcing experiment.

This is one of the few strong chive-specific temperature references.

But it applies to:

forcing plants after seasonal rest.

It should not automatically become:

the universal temperature for every chive stage.

21. At Lower Forcing Temperatures, Long Days Became More Important

The same research found that when lower forcing temperatures were used:

rest induction should be avoided using long-day conditions.

Again we see the interaction:

temperature × photoperiod.

This is a much better chive-specific developmental model than a generic:

PAR × CO₂ × VPD

stage chart.

22. Real Greenhouse Data Also Show Temperature and RH Affect Production Together

A 2016 Colombian study monitored commercial greenhouse chives for:

three years.

Three greenhouses had channel heights of:

2.0 m

2.5 m

and:

3.0 m.

Changing greenhouse height altered both:

temperature
relative humidity

and crop production.

23. The Lower Greenhouse Was Warmer and Produced Slightly More Fresh Weight

Reducing minimum greenhouse height from:

3 m → 2 m

increased approximately:

minimum temperature by 0.37°C
average temperature by 1.42°C
maximum temperature by 3.56°C

The lower greenhouse produced approximately:

4.78% more fresh chive weight

under those local conditions.

24. But This Does Not Prove “Warmer Is Better”

Greenhouse height changed the entire microclimate.

Temperature and relative humidity changed together.

The experiment was not a controlled:

temperature-only response curve.

Therefore the correct conclusion is:

greenhouse microclimate can measurably change chive production.

Not:

raising temperature by 1.4°C always increases yield by 4.78%.

25. CO₂ Has Direct Chive-Containing Research

A controlled-environment Allium experiment included three common-chive cultivars:

‘Fine Leaf’
‘Purly’
‘Staro’

along with onion and bunching-onion cultivars.

Plants were grown hydroponically under approximately:

400 ppm

or:

1200 ppm CO₂.

The environment used:

16 h light / 8 h dark

and approximately:

24/20°C day/night.

26. Elevated CO₂ Increased Biomass Across the Evaluated Allium Material

Across cultivars and harvest ages, plants grown at:

1200 ppm

had greater:

biomass
percentage edible biomass

than plants grown around:

400 ppm.

A later repeated-harvest Allium experiment likewise reported the greatest average biomass under:

1200 ppm CO₂.

Common chives were included directly in these experiments.

27. But 1200 ppm Is Not Proven to Be the Chive Optimum

The experiments compared:

400 vs 1200 ppm

rather than mapping a complete curve such as:

400 / 600 / 800 / 1000 / 1200 / 1400 ppm.

Therefore:

1200 ppm is a direct research treatment.

It is not:

the proven optimal commercial greenhouse concentration.

28. The CO₂ Experiment Used Very Strong Light

One of the Allium experiments used approximately:

660 µmol/m²/s

with:

16-hour photoperiods.

That would correspond to a very high constant-light DLI if applied throughout the full photoperiod.

The plants therefore had abundant light compared with many winter greenhouses.

This matters because CO₂ response depends partly on whether sufficient photons are available.

29. CO₂ Cannot Be Interpreted Without the Light Environment

An elevated CO₂ response under strong controlled lighting does not prove the same biomass benefit under:

very low winter DLI.

If photons are strongly limiting, additional carbon may not produce the same response.

Therefore monitor:

PAR / DLI + CO₂

together.

30. Elevated CO₂ Did Not Improve Every Chive Quality Metric

The 400 vs 1200 ppm study also measured total flavonols.

For the common-chive cultivars:

Fine Leaf
Purly
Staro

total flavonol concentrations appeared:

unaffected by elevated CO₂.

This is an important tradeoff.

Higher biomass did not mean:

every phytochemical increased.

31. Elevated CO₂ Also Should Not Be Claimed to Improve Chive Flavor

The same research program investigated sensory characteristics across Allium crops.

However, there was insufficient common-chive material for the chive cultivars to be included in the reported sensory panel.

Therefore the evidence does not support saying:

“1200 ppm improves chive flavor.”

32. Chive Flavor Is Chemically Complex

Recent 2026 chemical research identified large numbers of volatile signals across chive tissues.

Sulfur-containing compounds are particularly relevant to the characteristic:

onion-like
sulfurous
green

aroma of chives.

But current direct research does not establish a clean:

PPFD → flavor

or:

VPD → flavor

response curve.

33. Cultivar Also Changes Chive Aroma

A 2026 analysis of several chive cultivars found substantial differences in volatile profiles.

Hundreds of volatile compounds were detected, with many differential aroma compounds among cultivars.

Therefore, if two chive crops taste different, first consider:

cultivar
plant part
harvest age
postharvest history

before attributing the difference to VPD.

34. VPD Is Not a Chive Flavor Meter

VPD tells us:

atmospheric evaporative demand.

It does not directly measure:

sulfur volatiles
pungency
onion aroma
sensory tenderness

Therefore the old claim that VPD determines whether chives remain tender or flavorful goes beyond current direct evidence.

35. Chives Have Direct Repeated-Harvest Research

This is particularly important because regrowth is a core part of chive production.

A 2005 controlled-environment experiment grew common chives for:

70 days

and compared harvest intervals of approximately:

7 days

and:

14 days.

Shoot removal began around:

28 days after planting.

36. Chives Continued Producing New Leaves Later in the Experiment

Chives were relatively slow to establish compared with some other Allium crops.

But between approximately:

56 and 70 days after planting

they produced increasing numbers of leaves.

The experiment demonstrates that repeated harvest is biologically central to chive production.

37. But the Study Does Not Prove One VPD Produces Faster Regrowth

The repeated-harvest study manipulated:

harvest interval
spacing
CO₂

not VPD.

Therefore, the old claim:

“Once VPD was corrected, chives regrew faster after cutting”

cannot be presented as research evidence.

Regrowth depends on a much wider system.

38. What Can Affect Regrowth?

After cutting, continued leaf production can depend on:

remaining root and bulb reserves
clump age
harvest height
cutting frequency
light
temperature
CO₂
nutrient availability
root-zone water
seasonal rest state

That is a much more biologically plausible framework.

39. Plant Density Also Changed Chive Morphology

The repeated-harvest research compared approximately:

10, 15 and 20 mm plant spacing

under its controlled system.

Leaf diameter increased with wider spacing.

At:

20 mm spacing

chives developed tillering clumps of rhizomes.

This means:

leaf thickness can respond to crop density.

40. Therefore “Thin Leaves = Wrong VPD” Is Not Defensible

Leaf diameter can be influenced by:

density
cultivar
age
light
nutrition
water status

A thin chive leaf does not uniquely diagnose:

high VPD.

Before changing humidity, check the full production system.

41. Older Leaves Are Naturally Different From New Regrowth

University of Wisconsin Extension notes that older chive leaves become:

tougher than younger leaves.

Cutting plants back after flowering can stimulate production of:

new, tender foliage.

This provides a simple alternative explanation for texture differences:

leaf age.

42. Harvest Maturity Must Therefore Be Controlled

Suppose Crop A is harvested shortly after regrowth.

Crop B is allowed to become older before cutting.

If Crop B is tougher, it would be incorrect to automatically conclude:

its VPD was too high.

The leaves were at different physiological ages.

43. Root-Zone Salinity Has Strong Direct Chive Evidence

A 2018 experiment tested irrigation water salinity levels of:

0.38

1.0

2.0

4.0

6.0

and:

8.0 dS/m.

Researchers measured:

fresh weight
dry weight
plant height
evapotranspiration
water-use efficiency

All changed significantly as salinity increased.

44. Chives Were Classified as Salt-Sensitive

The study estimated a soil-salinity threshold of approximately:

1.13 dS/m.

Above the threshold, relative yield declined by approximately:

6.19% per unit increase in soil salinity

under the experimental conditions.

This is a much more direct chive-specific stress relationship than the old VPD claims.

45. Do Not Turn 1.13 dS/m Into a Universal Hydroponic EC Limit

The study examined:

irrigation-water salinity and resulting soil salinity

under its own pot/rain-shelter conditions.

That is not identical to:

NFT nutrient-solution EC
coco EC
hydroponic root-zone EC

Therefore, the exact threshold should be used only in its experimental context.

46. The Main Lesson Is That Chive Roots Are Sensitive to Salinity Stress

If greenhouse chives show:

reduced growth
shorter leaves
yield loss

under acceptable light, investigate:

irrigation-water quality
substrate EC
fertilizer accumulation
drainage

before assuming the problem is atmospheric humidity.

47. Root-Zone Stress and VPD Are Different

This distinction is essential.

VPD

describes how strongly the air can drive water loss.

Root-zone water and EC

describe how easily roots can replace that water.

A crop can have:

high VPD + excellent root water supply

or:

moderate VPD + saline / dry roots.

The physiological consequences are different.

48. There Is No Validated Chive VPD Stage Table

Current chive-specific research does not establish a scientifically validated sequence such as:

0.4–0.8 kPa during establishment
0.6–1.0 during early growth
0.8–1.2 during main growth
1.0–1.3 before harvest

Those values should therefore be removed from the old article.

49. Experimental RH Is Not Proof of a VPD Optimum

Some controlled chive research used very high RH conditions.

Other greenhouse production occurred under different temperature and humidity environments.

Successful growth under one RH does not prove:

that RH or calculated VPD is optimal.

A valid VPD optimum requires an experiment that intentionally compares multiple VPD treatments while controlling other variables.

50. What VPD Is Actually Useful For

VPD remains useful because it describes:

atmospheric water demand.

As:

temperature rises
humidity falls

VPD generally increases.

That can increase:

transpiration
irrigation demand
root-zone drying

Therefore, VPD is useful for diagnosing:

why water demand changed.

51. High VPD Does Not Automatically Mean Stomata Are Closed

The old article stated:

high VPD → partial stomatal closure → poor CO₂ uptake.

This can happen in plants under sufficiently strong atmospheric demand.

But whether it occurs depends on:

species
leaf temperature
root water availability
severity and duration
acclimation

A fixed VPD number cannot prove chive stomata are closed.

52. Measure Plant Response Instead of Assuming It

If a high-VPD period coincides with poor growth, check:

substrate moisture
irrigation frequency
EC
leaf turgor
temperature
CO₂
recovery after conditions normalize

Do not diagnose stomatal closure from VPD alone.

53. VPD Is Not a Tenderness Meter

The old article linked high VPD with:

thin, stiff leaves

and a particular preharvest VPD with:

softer leaves.

Current chive-specific research does not validate those causal relationships.

Leaf tenderness is also influenced by:

leaf age
cultivar
density
water status
harvest interval

Measure texture directly if it matters commercially.

54. Shelf Life Has Strong Direct Chive Evidence

Chives have much better evidence for:

postharvest temperature

than for preharvest VPD.

A 2009 study stored fresh chives at:

0°C

and:

4°C.

Researchers followed:

weight loss
surface color
chlorophyll
carotenoids
sugars
browning
phenolics
antioxidants
vitamin C

55. 0°C Preserved Quality Better

Storage at:

0°C

delayed:

surface-color change
loss of green pigments
reducing-sugar loss

relative to warmer storage.

Browning increased less at 0°C than at 4°C.

High overall quality and marketability were maintained for approximately:

2 weeks at 0°C.

56. This Is Much Stronger Evidence Than a Preharvest VPD Claim

The old article claimed a particular preharvest VPD caused:

less yellowing
better cut quality

But direct postharvest chive research shows a very clear lever:

cold storage.

If yellowing after cutting is the commercial problem, cold-chain management deserves priority.

57. Packaging and Hydrocooling Also Matter

A separate chive study stored leaves around:

10 ± 2°C

and compared:

packaging
no packaging
hydrocooling
no hydrocooling

Plastic packaging or PVC film greatly reduced fresh-weight loss.

When combined with hydrocooling, these methods helped preserve:

chlorophyll
carotenoids
postharvest quality

and extended useful storage in that study.

58. Modern Chive Research Again Shows Refrigeration Is Critical

A 2021 study compared chives stored at:

20°C

and:

3°C

with or without 1-MCP.

In preliminary work:

room-temperature chives lasted only about 5 days
refrigerated chives could be followed for about 20 days

The study also emphasized chives’ very high postharvest respiration rate.

Again:

postharvest temperature matters directly.

59. Shelf Life Should Not Be Presented as a VPD Setting

Preharvest environment can influence plant condition.

But after harvest, chive deterioration depends strongly on:

temperature
respiration
dehydration
packaging
storage duration
sanitation

Therefore:

“VPD 1.0–1.3 kPa improves chive shelf life”

should be removed unless a direct experiment demonstrates it.

60. A Practical Greenhouse Measurement Workflow

Step 1 — Identify the Production System

Are the chives:

seedlings
first-harvest plants
mature clumps
repeatedly harvested clumps
dormant stock being forced?

These are different physiological states.

Step 2 — Measure PAR at Leaf Height

Measure where the vertical chive leaves actually intercept light.

Step 3 — Record DLI

Especially in greenhouse production.

Compare:

sunny vs cloudy days
summer vs winter
supplemented vs unsupplemented benches

Step 4 — Record Spectrum When Comparing Fixtures

The commercial greenhouse trial shows that equal supplemental PPFD can produce different results under different spectra.

Step 5 — Record Photoperiod

For perennial chives, day length can influence:

rest-period behavior

independently of DLI.

Step 6 — Monitor CO₂

Compare crop-zone CO₂ with:

PAR
ventilation
time of day

Step 7 — Measure Root-Zone Conditions

Track:

moisture
nutrient EC
irrigation-water quality
drainage

Step 8 — Track Temperature, RH and VPD Together

Use VPD to understand atmospheric water demand.

Do not use it as a direct texture target.

Step 9 — Record Harvest History

Record:

days since previous cut
cutting height
harvest frequency
clump age

Step 10 — Record Crop Response

Measure:

fresh yield
leaf number
leaf diameter
regrowth time
yellowing
marketable percentage

If tenderness or flavor matters, evaluate those traits separately.

61. Practical Research-Based Light Reference

The strongest commercial greenhouse trial provides this useful context:

Natural greenhouse DLI

Average:

~8.5 mol/m²/day

with a range of approximately:

4–18.

Supplemental light

70 µmol/m²/s supplemental PPFD

providing:

6.05 additional DLI.

Supplementation approximately doubled fresh and dry biomass.

That is strong evidence that winter greenhouse chives can be light-limited.

62. What DLI Can We Defend?

Approximately:

8–15 mol/m²/day

is well represented by the commercial greenhouse experiment when considering its natural-light average and supplemental treatments.

But the natural DLI itself ranged widely.

Therefore, these values should be treated as:

research context

not:

a universal optimum band.

The authors explicitly stated that the precise optimum still required further study.

63. What PPFD Can We Defend?

The strongest commercial study added:

70 µmol/m²/s

supplemental PPFD to natural greenhouse sunlight.

It did not establish a constant total-canopy PPFD optimum.

Therefore:

we should not publish 250–400 PPFD as a proven mature-chive requirement.

Measure the actual greenhouse DLI instead.

64. What Photoperiod Can We Defend?

Approximately:

14 hours

is an important chive-specific photoperiodic threshold in classic rest-period research.

Shorter days at appropriate temperatures promoted rest induction.

Long days helped maintain active growth.

This is developmental evidence — not a DLI optimum.

65. What Temperature Can We Defend?

For forcing established chive plants after rest:

22–24°C

produced the highest growth rates in the classic experiment.

This is a useful direct research reference.

It should not be interpreted as:

the ideal temperature for every stage and every production system.

66. What CO₂ Can We Defend?

Direct Allium research including three common-chive cultivars compared:

~400 vs 1200 ppm.

Plants at elevated CO₂ generally produced more biomass and edible biomass.

But chive flavonols were not clearly increased.

Therefore:

1200 ppm is a direct experimental reference, not a universal chive optimum.

67. What VPD Can We Defend?

At present:

no validated common-chive stage-specific VPD optimum.

Use VPD to understand:

atmospheric water demand
irrigation changes
heat / humidity events

Do not use it as a direct predictor of:

leaf tenderness
regrowth
stomatal closure
yellowing
shelf life.

68. What Regrowth Advice Can We Defend?

Direct research confirms chives tolerate repeated cutting.

But regrowth should be interpreted through:

harvest interval
cutting height
clump reserves
photoperiod
seasonal rest state
light
CO₂
water
nutrition

not VPD alone.

69. A Better Way to Think About Chive Measurements

Instead of asking:

What PPFD keeps chive leaves tender?

ask:

Is daily light limiting biomass, and what spectrum is being delivered?

Instead of:

What VPD gives fastest regrowth?

ask:

What is the plant’s harvest history, seasonal state and actual water environment?

Instead of:

What CO₂ level should I maintain?

ask:

Does elevated CO₂ improve biomass under the available DLI enough to justify enrichment?

Instead of:

Why are the leaves thin?

ask:

Could plant density, leaf age, light, nutrition or root-zone stress be contributing?

Instead of:

How do I prevent yellowing after harvest?

ask:

How quickly are the leaves cooled, packaged and kept hydrated?

Those questions are much closer to current chive science.

Final Takeaway

Greenhouse chives do not have one scientifically established PAR, CO₂ and VPD recipe for tender foliage, rapid regrowth and long shelf life.

But chives have several strong crop-specific research findings.

Supplemental greenhouse light can dramatically increase yield.

A commercial hydroponic greenhouse trial received approximately:

8.5 mol/m²/day natural DLI on average

with natural conditions ranging from approximately:

4 to 18 DLI.

Supplemental-light treatments added approximately:

6.05 mol/m²/day.

All supplemental treatments produced about:

twice the shoot fresh and dry weight

of the natural-light control.

But spectrum mattered too.

The:

20% blue / 80% red LED

treatment produced approximately:

37% more fresh weight than HPS

and approximately:

20% more total carotenoids than natural sunlight alone.

Therefore:

DLI matters, but spectrum cannot be ignored.

Photoperiod also has a special developmental role.

Classic chive research found rest induction was associated with short days, with a critical day length around:

14 hours

under suitable temperatures.

Long days could help maintain active autumn growth.

Forcing experiments later found:

22–24°C

produced the highest growth rates after the rest period.

This means chive production should consider:

seasonal physiology + photoperiod

not only instantaneous PAR.

CO₂ matters, but there is no universal optimum.

Controlled Allium research including the common-chive cultivars:

Fine Leaf
Purly
Staro

compared approximately:

400 vs 1200 ppm CO₂.

Elevated CO₂ increased biomass overall.

But chive total flavonols appeared largely unaffected.

Therefore:

more biomass does not mean every quality trait improves.

Regrowth is a real production characteristic, but VPD is not proven to control it.

Chives have been directly studied under repeated:

7- and 14-day harvest schedules

over a 70-day production period.

Spacing, harvest history, CO₂ and plant developmental state all affected the production system.

Root-zone stress matters strongly.

Direct salinity research classified chives as relatively salt-sensitive, with yield declining as root-zone salinity increased.

So a poorly growing crop with apparently adequate PAR may have a:

root-zone problem rather than an atmospheric problem.

For VPD, current chive-specific evidence does not justify the old:

0.4–1.3 kPa stage table.

VPD should be used to understand:

atmospheric water demand

and interpreted together with:

temperature
root-zone water
EC
actual plant response.

Finally, shelf life has much stronger direct evidence.

Fresh chives stored at:

0°C

retained high quality and marketability for approximately:

2 weeks

in one direct study, with slower pigment and sugar losses than at 4°C.

Other chive research shows:

hydrocooling
packaging
low temperature

can substantially reduce water loss and quality deterioration.

Therefore, postharvest yellowing and shelf life should not be attributed to one preharvest VPD value.

The stronger greenhouse strategy is:

Measure PAR at the actual leaves.

Record DLI through the complete day.

Record spectrum and photoperiod separately.

Monitor CO₂ during active photosynthesis.

Track root-zone water and EC.

Use temperature, RH and VPD together to understand water demand.

Record harvest interval and clump developmental state.

Then compare those measurements with:

fresh yield, leaf diameter, regrowth time, tenderness, color and postharvest quality.

That provides a much stronger technical basis for greenhouse chives than unsupported stage-by-stage PAR / CO₂ / VPD targets.

References

Sams, C.E., Wheeler, J. & Kopsell, D. Supplemental Light Improves Yield and Quality of Chives in a Commercial Hydroponic Production System. American Society for Horticultural Science Annual Conference, 2016.

Krug, H. & Fölster, E. Influence of the Environment on Growth and Development of Chives (Allium schoenoprasum L.). I. Induction of the Rest Period. Scientia Horticulturae, 1976.

Krug, H. & Fölster, E. Influence of the Environment on Growth and Development of Chives (Allium schoenoprasum L.). II. Breaking of the Rest Period and Forcing. Scientia Horticulturae, 1977.

Broome, A.L. & Peffley, E.B. Effect of Planting Density, CO₂, and Harvest Intervals on Biomass of Three Allium Species. HortScience, 2005.

Thompson, L., Peffley, E., Green, C., Paré, P. & Tissue, D. Biomass, Flavonol Levels and Sensory Characteristics of Allium Cultivars Grown Hydroponically at Ambient and Elevated CO₂. SAE Technical Paper, 2004.

Bustamante, N., Acuña, J.F. & Valera, D. Effect of Greenhouse Heights on the Production of Aromatic Herbs in Colombia. Part 1: Chives (Allium schoenoprasum L.). Revista Colombiana de Ciencias Hortícolas, 2016.

Arslan, H., Kiremit, M.S. & Güngör, A. Impacts of Different Water Salinity Levels on Salt Tolerance, Water Use, Yield, and Growth of Chives (Allium schoenoprasum). Communications in Soil Science and Plant Analysis, 2018.

Viña, S.Z. & Cerimele, E.L. Quality Changes in Fresh Chives (Allium schoenoprasum L.) During Refrigerated Storage. Journal of Food Quality, 2009.

Guerra, A.M.N.M. et al. Hydrocooling and Packaging in the Post-Harvest Conservation of Chives (Allium schoenoprasum). Agrarian, 2020.

1-Methylcyclopropene Preserves the Quality of Chive (Allium schoenoprasum L.) by Enhancing Its Antioxidant Capacities and Organosulfur Profile During Storage. Foods, 2021.

Zhou, C. et al. Research on Volatile Flavor Substances and Biological Activities of Different Parts of Allium schoenoprasum L. Frontiers in Nutrition, 2026.

Wisconsin Horticulture Extension. Chives, Allium schoenoprasum. Revised 2026.

Related AquaHorti Tools

For instantaneous PAR / PPFD measurements and comparing light distribution across a greenhouse chive crop, see AquaHorti AH-Quantuv.

For recording changing greenhouse PAR throughout the day and measuring DLI, see AquaHorti AH-PARDLI.

For greenhouse monitoring where PAR, DLI, CO₂, temperature, humidity and VPD need to be reviewed together over time, see AquaHorti AH-200.