Reds are tricky. They are sensitive to how high the heat is, the acidity of the water, the mordants and modifiers you use and, it sometimes feels like, the cycle of the moon.
"Reds" include the dyes that produce pinks, purples, oranges, and true reds. The medieval "reds" available were (and that I have used) madder, bedstraw, lac, cochineal, sappanwood, and logwood.
The "reds" are generally not light or washfast, with the exception of madder, which is likely why it was the most used red dye in the middle ages.