How much light do indoor plants need? The light quantum flux density PPFD of the plant grow light

Different plants and different growth stages have different lighting requirements. The following are the lighting requirements for several indoor plants.

         Basil under the grow light


As mentioned above, the light requirements of plants in the seedling stage, vegetative growth stage, flowering stage and fruiting stage are different. Through artificial light sources, we can well control the illuminance and even the spectrum. The following is a simplified version of the PPFD requirements of the various growth stages of the plant:


  1. Tissue culture

The light required for tissue culture is about 40-60 µmol/m²/s, and most plant varieties, the illumination required for tissue culture is in between!

  Tomato seedlings


  1. Seedlings (light in the seedling stage of most crops)

The light in the seedling stage is usually 150-250µmol/m²/s, and different crops will vary.


  1. Vegetative growth period

The light in the vegetative growth period of leafy vegetables is 250-350µmol/m²/s. Most leaf vegetables can meet the light requirement with an average light of 250µmol/m²/s. However, some leaf vegetables, such as large fast lettuce, can be given higher light to meet Need for rapid growth

High-light plant vegetative growth PPFD: 300-600µmol/m²/s, such as flowering plants such as tomatoes, cucumbers, and medicinal plants.

Plant Light Spectrum Experiment Cultivation Baby Lettuce


Tomato cultivation test flowering stage



  1. Reproductive growth stage, That is flowering and fruiting period.

During this period, higher light will increase the harvest. By increasing far-red light and ultraviolet UV light, the amount of flowering and the taste or Secondary metabolites content will be increased. In the case of 400ppm without adding carbon dioxide content, the light is 350 -600µmol/m²/s.

If the carbon dioxide content can be increased to 1200ppm, the light can be increased to 800-1200µmol/m²/s, which can significantly increase the yield. Specific varieties such as tomatoes and high-light medicinal plants etc.


In fact, medicinal plants that have been legalized in many countries, The illumination PPFD can be increased to 1600 µmol/m²/s, There is still high-efficiency photosynthesis and high-speed growth. Of course, this requires a good other planting environment elements, Such as temperature,CO2, relative humidity, air circulation, fertilizer rate, substrate, pH, and electrical conductivity (EC).


  1. Ornamental plants such as succulents and cordyceps, PPFD: 250-350µmol/m²/s


PPFD, µmol/m²/s and Lx conversion, there can only be a rough calculation, and it must be a white light-based plant lamp, 60-70Lx is equal to 1µmol/m²/s, due to spectral reasons, red and blue More plant lights are not suitable for this ratio.

There is a PPFD test report at the end, please refer to it.


Tell us the varieties you planted, the planting environment, and we will give you the lighting plan!