Typical PPFD and DLI values per crop

PPFD and DLI values differ enormously by crop, and getting them right is the difference between a grow light that's wasting electricity and one that's actually driving growth. PPFD (Photosynthetic Photon Flux Density) measures light intensity at a single moment, while DLI (Daily Light Integral) totals up how much light a plant receives across a full day. This guide sets out typical PPFD ranges for common hydroponic crops and potted plants, along with the formula for converting between the two, so you can dial in your grow lights with confidence.

💡 What Are PPFD and DLI?

Plants absorb radiation mostly in the 400–700nm visible range, using it to convert CO₂ and water into oxygen and glucose through photosynthesis. How much of each wavelength a plant absorbs depends on its cellular structure, which is one reason light requirements vary so much between species.

PPFD is measured in µmol/m²/s and tells you the light intensity hitting your canopy right now. DLI is measured in mol/m²/d and tells you the total photon count your plants receive over 24 hours — it accounts for both intensity and photoperiod length. Values between roughly 6 and 18 mol/m²/d are common depending on the plant, though fruiting and flowering crops often sit higher again.

💡 A-Grade Tip: To use the figures below, you'll need a way to measure light in your grow space. A dedicated quantum meter is the most accurate option. If you don't have one yet, our budget light measuring guide covers lower-cost alternatives.

↔ Converting Between PPFD and DLI

PPFD and DLI are linked by photoperiod (the number of hours your lights are on each day):

DLI = PPFD × light hours per day × (3,600 ÷ 1,000,000)

This formula shows the trade-off between light intensity and photoperiod length: a lower PPFD run for more hours can reach the same DLI as a higher PPFD run for fewer hours. In a greenhouse, any natural light already falling on the crop needs to be subtracted from the target DLI before calculating how much supplemental lighting is required.

Worked example — converting a DLI target into a PPFD value for a 16-hour photoperiod:

• 12 mol ÷ 16 hours ÷ 60 minutes ÷ 60 seconds = 0.000208 mol per second per m²
• 0.000208 mol × 1,000,000 = 208µmol/m²/s required PPFD

🌱 Typical PPFD Values for Vegetable & Fruiting Crops

These figures are commonly cited reference ranges rather than a single fixed target — treat them as a starting point and adjust based on how your plants respond.

For greenhouse-grown fruiting crops like tomato and pepper, growers commonly target a DLI in the 20–40 mol/m²/d range, while leafy greens and herbs typically need a minimum of around 17 mol/m²/d in a greenhouse or 12–17 mol/m²/d indoors. Microgreens sit lower again, generally 6–12 mol/m²/d.

🌸 Typical PPFD Values for Potted & Flowering Plants

🌿 A Note on High-Light Flowering Crops

Some flowering and fruiting crops grown under intense LED or HID lighting – particularly during a dedicated bloom phase – are commonly run at PPFD levels well above 500µmol/m²/s, with some advanced setups pushing past 1,000µmol/m²/s where CO₂ enrichment and climate control are dialled in. Published figures for the upper end of this range vary noticeably between sources, so rather than quote a single ceiling here, the safest approach is to increase PPFD gradually and watch how the plant responds rather than jumping straight to the highest number you've seen quoted.

💡 A-Grade Tip: If you push light levels higher, your plants will draw more heavily on nutrients to keep pace with the extra photosynthetic capacity — keep an eye on your feeding schedule as you increase PPFD.

Matching your grow lights to the right PPFD and DLI target for each crop is one of the simplest ways to avoid under- or over-lighting your plants. Browse A-Grade Hydroponics' range of LED grow lights and quantum meters to get your light levels dialled in, and get in touch if you'd like a hand choosing the right setup for your crop.