Be sure to test after treating with Retayne. Some fabrics need two treatments. If a fabric still bleeds after two treatments with Retayne, don't use it in a quilt.
Regarding your Christmas tree skirt, I recommend always doing a first wash in Synthrapol -- which suspends unset dye particles in the water so they do not settle into other fabrics. You do need a washing machine that uses a lot of water in order to keep the dye sufficiently diluted; domestic front-loaders don't use enough water. Once there is a bleed, Synthrapol will usually remove it (because the dye has not been chemically set), but it can take several washings.
Both Retayne and Synthrapol require *hot* water to work.