Hydrogen peroxide can potentially kill most things living in the soil (i.e bacteria, fungi including mycorrhizae). Most cells have peroxidases to catalyze the breakdown of minor amounts, but the right concentration will harm most any cell including root or human skin cells.
Just let the pot dry out. Add a fan or two to improve air circulation, or if possible increase the lighting to hasten drying. Good soil structure should reduce the harm from overwatering, which is really due to lack of oxygen in the rhizosphere as the roots breath oxygen. It is also required for the beneficial obligate aerobic organisms to live.
Organic nutrients are generally low NPK with less of a tendency to burn, unless you really over did it in that one application.
oh and cinnanon does it really enchance flavor as some Mg[SUP]2+[/SUP]?
Not really sure what you mean by this... and magnesium? I don't believe that cinnamon enhances anything although I have heard of it being used to deter pests.
Flushing isn't really necessary in soil and most people who grow in organic\living soil wouldn't "flush" at all, ever, just water regularly. In a living soil, various microbes are working in concert with the plant, functioning to seek out, break down, retain and/or release nutrients in plant available form for the plant at all times. Also, soil has a means by which it, itself, can retain certain nutrients, primarily mineral cations which include NH[SUB]4[/SUB][SUP]+[/SUP], K[SUP]+[/SUP], Ca[SUP]2+[/SUP], Mg[SUP]2+[/SUP], Fe[SUP]2+\3+[/SUP], Na[SUP]2+[/SUP], etc. Cations are attracted and loosely bound to very small particles (i.e. those of clay and humus) which posses a net negative charge, preventing them from leaching out of the soil whilst remaining available to plants. Cation exchange capacity refers to how well a medium can retain nutrients. Soils higher in clay and humus also have a greater CEC, while sandy soils lack CEC (cannot hold onto nutrients). Coco coir and sphagnum peat moss also have CEC and are much lighter materials.
In hydroponics the fertilizers used are often much higher in NPK and most hydro nutrients also contain synthetic chelating agents (EDTA, DTPA) to increase the uptake of nutrients (including heavy metals). This replaces the role of humus and microbes in the rhizosphere, and the plants are basically being force-fed.
