Marble chips for light reflection

Hey folks,

I've been wondering at the possibilities of using marble chips, white sand or something similar on the surface of soil to provide some light reflection while allowing air through to the roots. It strikes me that an exposed soil surface absorbs a significant proportion of light energry in an otherwise highly reflective mylar-lined box setup, particularly in the early stages of a grow.

Anyone done this or something similar? Any negative effects on soil PH from using marble? Any other issues I might be missing?

Hmm that's an interesting idea. I have heard of people wrapping up there pots in white construction paper to A) keep the root zone cool. B) reflect light down low that's not geing used. Some people coat the top layer of soil with perilite for various reasons, none that I've heard are for light reflection

Why don't you break off some of that mylar or use aluminum foil?

This is an easy one.
I always dump about a cup of Pearlite on top of my soil & since it floats I keep a nice white layer on top of the dirt.
Very bright compared to soil
Breathable
Replaceable if necessary
Cheap.

You're welcome !

best thing to do is put 2 inches of white sand around your plant not only does it reflect light but you wont have any bugs or gnats coming up through your soil as it forms a crusty top when dry. this was a very big help to me for pest control, now i have no pests prevention is better than the cure

Muffy said:

Why don't you break off some of that mylar or use aluminum foil?

Click to expand...

I've considered a pot lid coated in mylar with a hole for the stem, but I don't like the idea of a non-breathable surface for fear of mould thriving on the soil underneath.

GreatwhiteNorth said:

This is an easy one.
I always dump about a cup of Pearlite on top of my soil & since it floats I keep a nice white layer on top of the dirt.
Very bright compared to soil
Breathable
Replaceable if necessary
Cheap.

Click to expand...

Many thanks for the help. I ask about marble specifically as I have access to small marble chips in abundance. I am considering a small low-wattage ScrOG setup, and wondering if a bed of white marble in a big square pot would act as a good reflector for a number of small CFL bulbs placed under the screen. I'm thinking marble or white sand might provide a nice bright diffuse reflection to spread some light evenly on the underside of the canopy, supplementing a brighter but still modest overhead light source.

Perhaps perlite is the way to go, or white sand as suggested by kangdark.