Measuring Daily Light Integral (DLI)
Introduction
The daily light integral (DLI) concept measures the total amount of photosynthetic light plants receive during the day — not just the intensity of sunlight at a given moment.
Conceptually, DLI is similar to how we measure rainfall. To measure DLI, we “collect” light throughout the day similar to a rain gauge.
Authors
Ariana P. Torres, Christopher J. Currey, and Roberto G. Lopez, Purdue University; and James E. Faust, Clemson University
How Does DLI Affect Growth?
Increasing DLI can:
- Increase plant mass (roots, shoots and flowers)
- Increase branching
- Reduce time to flower
- Increase flower size and number
How Can You Measure DLI?
- There are different ways to measure DLI in your greenhouse, but the two most common methods use:
- Mobile quantum (photosynthetic light) sensors (with or without data loggers)
- Quantum sensors that are connected to the greenhouse environmental control system
Here are a few tips for using DLI sensors:
- Place sensors at plant height and adjust the sensor height as the crop grows
- Use a level to make sure the sensor is level
- Keep the sensor clear of dust and debris by periodically washing with distilled water and a tissue
- If possible, return your sensors to the manufacturer every few years for re-calibration
DLI requirements differ between greenhouse crops as outlined in the table inside this brochure.
sensor.
environmental control system.
More DLI information is available in Commercial Greenhouse Production: Measuring Daily Light Integral in a Greenhouse, Purdue Extension publication HO-238-W (also in Spanish as HO-238-SW). Available from the Purdue Extension Education Store.
DLI Requirements for Various Greenhouse Crops
1=Requires ample water to perform well at high-light levels.
2=Requires cool or moderate temperatures to perform well at high-light levels.
3=Stock plants perform well under higher light levels than finished plants.
| Average Daily Light Integral (Moles/Day) - Greenhouse | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Species | 2 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 | 26 | 28 | 30 |
| Ferns (Pteris Adiantum) | Minimum acceptable quality | Good quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data | No data | No data |
| Maranta | Minimum acceptable quality | Good quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data | No data | No data |
| Phalaenopsis (orchid) | Minimum acceptable quality | Good quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data | No data | No data |
| Saintpaulia | Minimum acceptable quality | Good quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data | No data | No data |
| Spathiphyllum | Minimum acceptable quality | Good quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data | No data | No data |
| Forced hyacinth | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Forced narcissus | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Forced tulip | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Aglaonema | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data |
| Bromeliads | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data |
| Caladium | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality (1) | High quality (1) | High quality (1) |
| Dieffenbachia | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data | No data |
| Dracaena | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data |
| Nephrolepsis | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data |
| Streptocarpus | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data | No data |
| Hosta | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality (1) | High quality (1) | High quality (1) |
| Hedera (English ivy) | No data | Minimum acceptable quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Begonia (heimalis) | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data |
| Sinningia | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data | No data |
| Schlumbergera | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality (2) | High quality (2) | High quality (2) | High quality (2) | High quality (2) | High quality (2) | High quality (2) |
| Cyclamen | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data |
| Exacum | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data |
| Heuchera | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data | No data | No data |
| Coleus (shade) | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data |
| Impatiens, New Guinea | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data |
| Iris, Dutch (cut flowers) | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data |
| Kalanchoe | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data |
| Lobelia | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality (2) | High quality (2) | High quality (2) | High quality (2) |
| Primula | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data | No data |
| Impatiens | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data | No data |
| Pelargonium peltatum (Ivy geranium) | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | No data | No data |
| Begonia (fibrous) | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Senecia (dusty miller) | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Fuchsia | No data | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality (2) | High quality (2) | High quality (2) | High quality (2) |
| Euphorbia (poinsettia) | No data | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality (3) | High quality (3) | High quality (3) |
| Hydrangea | No data | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Lilium (asiatic and oriental) | No data | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Lilium longiflorum (easter lily) | No data | No data | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Ageratum | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Antirrhinum | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Chrysanthemum (potted) | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Dianthus | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Gazania | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Gerbera | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Hibiscus rosa-siniensis | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Lobularia | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Pelargonium hororum (zonal geranium) | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Rose (miniature potted) | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Salvia splendens | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Schefflera | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Angelonia | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Aster | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Salvia farinacea | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Iberis | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Catharanthus (vinca) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Celosia | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Chrysanthemum (garden) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Coleus (sun) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Coreopsis | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Cosmos | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Croton | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Dahlia | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Echinacea | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Ficus bejaminia | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Gaura | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Gomphrena | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Hemerocallis | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Lantana | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Lavendula (lavender) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Tagetes (marigold) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Petunia | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Phlox (creeping) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Rudbeckia | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Scaevola | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Sedum | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Thymus | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Verbena | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality | High quality |
| Viola (pansy) | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality | High quality (2) | High quality (2) |
| Zinnia | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Alstroemeria (cut flower) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Capsicum (pepper) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Chrysanthemum (cut flower) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Dianthus (carnation) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Gladiolus (cut flower) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Lycopersicon (tomato) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |
| Rose (cut flower) | No data | No data | No data | No data | Minimum acceptable quality | Minimum acceptable quality | Good quality | Good quality | Good quality | Good quality | High quality | High quality | High quality | High quality | High quality |