Like most everyone else, I don't necessarily recommend MG soils for cannabis, because it's not really tailored to the needs of the plants, and time-released fertilizers can sometimes play hell on feeding regimens, soil pH, etc. But, like most everyone else, I've used it successfully in a pinch, and won't completely bash the stuff outright.

I don't remember exactly how much perlite is usually added to their mixes, but you could probably stand to add a little more regardless... especially if it happens to be a "moisture control" type of soil that likes to stay damp. I mix my own soil now, and my soil/perlite ratio is 3/1. I end up having to water a bit more frequently, especially right before transplants, but I prefer it that way since I have the extra time to notice if they need any special attention or not.

And for flowering you'll want to make sure you don't use a soil that's overly rich in Nitrogen. While some N is good to prevent the onset of early yellowing, too much of it will influence new foliage growth, instead of bud growth. Again, knowing what the N-P-K of the soil is will definitely play a part on what you'll need to feed the plants for best results.

Take care. :jointsmile: