I've never used as a foliar, but guess you could. Then again, I've never used guano. They grow pretty good with the nutes aquired thru the roots, tho. Especially with the MG, as you'll want the plant to use all the nutes in the soil asap. If any defeciencies are noticed, foliar or soil applications (nutes) will likely need to be increased.

If you must, you could add the guano into the soil mix you'll use for it's future transplants, but don't over-do it. Also, adding it to soil that will be used for seeedlings and clones will likely make the soil too 'hot', possibly causing death.

By the way...what Fox Farms products did you get?