closer than 20" to the bulbs
 

The vertical space in my grow room is slightly limited. I've read when my plants get closer than 20" to the bulbs they may get burnt, is this correct? Is there any way I can screen the light out when the plants start getting too close? Perhaps use a metal screen or some type of light barrier? Thank you

A tempered piece of glass between your plants and light is the only practical way I can think of.