It could be the detergent you are using…..they can be really harsh and fade clothing quickly. I use Sunshine Concentrate from Nature’s Sunshine and have not had an issue with fading.
I have also heard that when you have something new, to wash it in cold with a bit of vinegar to set the color, but I have not done it, so can’t vouch for that.
I always add baking soda to my wash it softens the water and makes the detergent work my efficiently. I don’t use fabric softner instead I use vinegar it also softens the water and it gets more of the detergent out of the clothes. I know this probably goes against everything you were taught, I know it does mine, but you might want to get the clothes inside and wash them that way too. That way it takes longer for the clothes to fade.