Importance of reflective material

How much increase percentage-wise does Mylar reflector plastic (mirror silver) add to yield?
New Zealand

It depends on the size and setup of your garden and the kind of reflector you are using. As a general rule, the smaller the garden, the more light misses the target and instead illuminates the walls or surrounding area. In a larger garden, side light reaches additional plants. Reflectors also differ in the way they direct light. Some create a more concentrated beam while others diffuse it over a larger area. Reflectors that diffuse it lose more light in small gardens.

In a single-light garden, reflective surfaces can increase the light getting to the garden by 50 percent or more. In a four-light garden, I tested light with and without reflectors made of Mylar stretched on a scaffold. The amount of light reaching the garden increased by more than 30 percent.

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