Grandma's is NOT BLACKSTRAP... it is like 2nd molasses or some kind of blend. Blackstrap molasses is thicker, darker, and less sweet- it has a more bitter taste. It is less commonly used for baking and may be found in the "Natural Foods" section of supermarkets, or at health food stores. Common brands are Plantations Blackstrap and Brer Rabbit.
Blackstrap is the FINAL by-product of sugar refining (from sugar cane or beets); it is what remains after the 3rd round of extraction (by boiling), where just about as much sucrose as possible has been removed from the material. Although it does still contain some carbohydrates: primarily sucrose, fructose, glucose, and raffinose (in beet molasess). It has a much higher potassium and mineral (iron, zinc, calcium, magnesium) content than a 1st or 2nd molasses like Grandmas.
Plant roots themselves have only been demonstrated to be able to take up very minor amounts of exogenous sugars like glucose and sucrose (they exude these compounds). It will be utilized by soil biota, where present.
Oh yea... Fungus Gnats. I never liked putting anything like sand on top of the soil, it can water in and get messy. If you use the wrong kind of sand you can end up clogging your medium up. Soil has to be able to breathe.
Go to the hardware store and look for Mosquito Bits, where the fly strips and pest products are. If they don't have the bits, just get the Mosquito Dunks. The actual product is called Bacillus thuringiensis israeli, along with it's associated toxin. It is a species of Bacillus (bacteria that form Endospores) which produces a toxin that only kills a small number of insect larva, including mosquito, fungus gnat and black-fly.
Bits are more convenient to use, Dunks you should break up and soak for about 12 hours in a gallon of water (half dunk is fine). Adults should be vacuumed up periodically if possible, get sticky stakes or hanging fly traps.
lol i usually start feedin mine molasses when they start their 3rd week
