I make a compost tea of 1 cup earthworm castings to 4.5 gallons of water, air bubbled for 24-48hrs for mycorrhizae additive. Wonderful stuff, gets the soil working overtime and the results on top of the soil is readily apparent.

An inch of sand on top of your soil puts an end to fungus gnats.

Usually I use Mycogro but after doing some reading, I am using just one strain of mycos, Rhizophagus intraradices, formally known as Glomus intraradices. I do have some MycoGro left so I will be doing a side by side to see if there is any difference. It will be hard to tell because all of my plants last year did so well and were very healthy. If things are the same this year then there may not be much difference.