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Measure input
Enter your LED PPFD and plant light category.
Plant care planning
Grow light & fertilizer tools
Light your plants correctly. Feed on schedule. GrowLight provides a grow light intensity calculator and fertilizer dilution tool for indoor and greenhouse growing.
Calculate light hours
Dilute fertilizer
4,217 calculations logged this quarter
Example greenhouse profile
DLI target22 mol/m²/day
LED schedule12h/day
Feed mix3.2ml/litre
Label: Bench A, spring basil crop. Expected correction from 9.8 to 21.7 mol/m²/day after extending the photoperiod and raising the fixture 14cm.
Grow Light Calculator
Estimate Daily Light Integral from LED PPFD and choose a practical photoperiod for the crop in front of you.
Current DLI
Target DLI
Hours per day recommended
Light assessment
How it works
A short workflow used by hobby growers and production benches alike.
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Check the DLI target
Review target DLI and recommended daily light hours.
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Balance feeding
Calculate fertilizer dilution for your water volume and target EC.
From the GrowLight journal
Short, data-led notes on indoor lighting and nutrient management.
Grow Lighting
Grow Lights Explained: PPFD, DLI, and Why PAR Watts Are Misleading
Marcus Ford on the numbers that actually matter at canopy level.
Read →
Fertilizing
Feeding Houseplants: Why More Is Almost Always Worse
Diana Holt outlines the common errors behind fertilizer burn and stalled roots.
Read →Light Requirements
The Light Requirements of Popular Houseplants: A Data-Based Reference
Simon Cole compares species by DLI range instead of vague labels.
Read →Trusted by growers who prefer numbers to guesswork
Specific adjustments, measurable outcomes.
“DLI target confirmed my tomato seedlings needed 14 hours, not the 10 I was giving them.”
— Chris V., Indoor Grower
“The fertilizer calculator stopped me from accidentally over-feeding a new cutting.”
— Helen R., Plant Propagator
“Precision tools with no subscription or app required.”
— Martin L., Hydroponics Hobbyist
Frequently asked questions
Definitions and field notes used in daily plant care planning.
What is DLI?
Daily Light Integral — the total amount of light delivered to a plant over 24 hours. It is measured in moles of photons per square metre per day.
What is PPFD?
Photosynthetic Photon Flux Density — the intensity of light useful to plants, measured in micromoles per square metre per second.
What is EC in fertilizer solutions?
Electrical Conductivity — a measure of dissolved nutrient concentration in water. Higher EC means more nutrients.
Can I over-light a plant?
Yes. Photobleaching and leaf burn occur above each species' maximum DLI tolerance, particularly with direct LED light at close range.
Should I fertilize in winter?
For most tropical houseplants in dormancy with low light and slow growth, reduce feeding frequency to monthly or stop entirely.
How accurate is the calculator?
It provides a planning estimate. Bench-level verification still depends on a measured PPFD reading taken at canopy height.