Shades and Light Diffusion

Sunlight is a key component for plant growth. However, natural sunlight is not the best light for plants. In fact, direct light may even damage plants. The same harsh rays that cause sunburns in people can also singe plant’s foliage. Studies show that diffused light is the best light for growing. Growth rates increase 20 to 30 percent under diffused light when compared to plants grown under more direct light. Diffused light reaches your plants from all angles, allowing light to contact leaves that would not normally get much light. Plants are consequently able to photosynthesize more and produce more food to promote healthy, robust growth.

Diffused light also produces fewer shade spots in your greenhouse, which means that plants don’t have to strain to reach towards available light. As a result, the plants develop bushy, compact growth opposed to unattractive, leggy growth. Some greenhouse coverings may diffuse light to some extent, but still transmit too much direct light.  This additional light may ultimately cause more harm than good because too much light causes plants to waste energy through transpiration. Excessive heat, also a consequence of more direct light, can stress plants and reduce photosynthesis rates.

If your greenhouse paneling does not naturally diffuse available sunlight you run the risk of harming your plants.  I lieu of changing your glazing or moving the position and site of your greenhouse, you can use a shade cloth.  Draped over the outside of your nursery, a shade cloth blocks or diffuses the light that enters your growing space.  The percentage of light blocked is determined by the weave and material of the blanket.  Most attach with grommets or to the frame of your nursery structure.  Be sure to use and position the shade cloth to provide the most protection possible for you plants; in the summer when the sun is highest in the sky, between 10 a.m. and 5 p.m. and over any greenhouse that has excessive western exposure.