It is generally known that even in the dark ages - i.e. the viking period - the merchant class and the nobility had access to dyed clothing and wore them routinely. Heck, if you were wealthy enough you could even get silk but that was truly special. Some dyes were cheap, others expensive. The expensive stuff was used on their finest gear. the cheap stuff was for everyday. The poor, well, there were sumptuary laws that said they weren’t allowed to wear fancy clothes (because ... poor) but those were hardly ever enforced. But we’re talking about the poor so yeah, dyes might have been an issue. But that doesn’t mean they never used them and lived in a pallet of brown and off-white.
But they would have used them sparingly because they were expensive and they were not color fast. With the exception of some very expensive dyes they would begin fading almost immediately. Washing, sunlight even rain would fade the colors so you wore them for special occasions. Or your pretty blue tunic would be gray in no time.