Per the SDS, Grow & Gain All Purpose Liquid Fertilizer 10-10-5 is not an organic product.
Per the manufacturer of Grow & Gain All Purpose Liquid Fertilizer 10-10-5 it will not stain. It is a pale greenish color before it is diluted and will just wash off if the concentrated liquid gets on anything. It would just look like water if it did contact surfaces.
Unfortunately, the gallon is the only size that we carry in the Grow & Gain All Purpose Liquid Fertilizer 10-10-5.
Grow & Gain All Purpose Liquid Fertilizer 10-10-5 is labeled for use on flowering plants, so it should be safe to be used on dahlias.