How Light Intensity and Duration Affect Indoor Plant Growth
The American Society for Horticultural Science (ASHS) logo. | American Society for Horticultural Science
Recent studies from Michigan State University provide valuable insights into how light management affects the growth, morphology, and flowering of both herbs and indoor foliage plants, offering practical guidance for greenhouse and indoor plant producers.
Photosynthetic Daily Light Integral Has a Greater Impact on Basil Flowering Than Photoperiod
The first study focused on basil, demonstrating that the daily light integral (DLI) — the total amount of light received by plants over the course of a day — has a greater effect on flowering than photoperiod, or day length. Basil plants exposed to higher DLI levels flowered earlier and more consistently, indicating that light intensity and total daily exposure are critical factors for scheduling harvests and ensuring consistent flower production.
Growth and Morphology of Seven Indoor Foliage Plants in Response to Day Length
The next study examined seven common indoor foliage plants and their responses to different day lengths. Plant morphology (including leaf size, stem elongation, and overall biomass) was influenced by photoperiod, with longer day lengths generally promoting more compact and vigorous growth in several species. The research highlights that day length can be used strategically to shape plant form and optimize appearance for the indoor plant market.
Together, the findings from these studies emphasize that both the amount of light received daily and the duration of light exposure play important roles in plant development. For herb producers, managing light intensity can help control flowering schedules, while indoor foliage growers can use day length adjustments to influence plant morphology and marketability.
The studies provide actionable guidance for growers using controlled environments such as greenhouses, vertical farms, and indoor plant production systems. Optimizing light management can improve plant quality, reduce production time, and support more predictable scheduling for both flowering and foliage crops.
Read Both HortScience Studies
For additional information, the full articles can be found on the ASHS HortScience electronic journal website:
- “Photosynthetic Daily Light Integral Has a Greater Impact on Basil Flowering than Photoperiod”
- “Growth and Morphology of Seven Indoor Foliage Plants in Response to Day Length”
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