I change their blankets twice a day…
I could never do what I do or buy what I buy or store what I store if I owned multiple horses. My horse has 3 sheets, 3 100gm fill and 3 mid weights. That way they only have to be laundered once during the season and once after. I have one mid weight that will probably not be used at all. I love it when I send them out, or put them in all clean and snuggly. I know I am odd.
My trainer has an array of stable and turnout blankets as part of her business. Horses that come in on lay up don’t come in with wardrobes. For her horses and the permanent boarders that are on field board, they generally get a blanket and wear it pretty much all winter. This year has been really mild so the medium weights have been on. It has not been cold enough to switch to heavy weights.
If she switches, then she cleans. Other than that, the blanket has to get REALLY dirty. We washed one recently that a yearling was wearing. Somehow he got mud under the blanket all the way up is rump and shoulders. It looked like he took a swim in a mudhole. So he and his blanket got cleaned.
As far as my horse, she doesn’t like blankets. Her first winter with my trainer she kept removing the blankets I had bought that were a bit big for her to grow into. One particularly cold winter I had a sheet for her to keep the snow off but a fieldmate tore it (and another horse’s) up. She grows a thick winter coat - thick enough that I can brush snow off leaving dry hair as none of it melted near her fur. I check her ears obsessively and she is always fine and wondering why I’m so enthralled with her ears.
I did give her a bath that one day near Christmas that it was 60 out. Don’t worry, she replaced all the dirt I removed…
The outsides of the turnout blankets are going to be muddy within a day pretty much no matter what, so I don’t see a ton of point in washing them. I just brush them off with a moderate brush.
The insides never get worse than a bit dusty. The horses are themselves dusty so the net result isn’t too bad.
Keeping them hung so that they can air out helps.
I don’t use layering - it seems to me that the multiple blankets have ended up being more uncomfortable than one that is a little dirty. YMMV.
I’m like you OP - my horse has a wardrobe and I’m a neat freak. His indoor sheets and light blankets will fit just fine in my stackable washer/dryer so I wash & rotate weekly.
So far he hasn’t needed the heavier blanket (250g) but if/when it gets dirty that will probably require either a trip to a laundromat or a pro clean.
Because of our weather fluctuations blankets do get switched our fairly often, but only sheets get cleaned more than once year. Outer layers get brushed off and laundered/waterproofed once a season.
I have two of each weight so I can switch out if they get soaked or filthy.
I will sometimes wash one of the sheets or medium weights in the middle of winter if they get really nasty (she likes to sleep in her pee)–but mostly I just send them all to be cleaned and re-waterproofed once a year.
Yes, I can handle up to mid weights…after that it is the laundromat!
I wash indoor rugs, coolers, rug liners around once a week. I purposely buy ones that will fit in my washing machine and dry very quickly (the stable rug brand I have now generally only takes an hour to dry). Outdoor turnout rugs generally get done once a year. I hate putting dirty rugs on the horse I’ve spent ages cleaning!
Front load may tag washer. No detergent but baby shampoo. No use of dryer but hang on the fence or line.
I wash often. Always in cold water, and with above restrictions. The blankets keep their waterproofing and are fine. My horses use the liners as well but don’t have to worry about waterproofing with liners. I do treat the liners just as I treat the blankets however.
No hot or warm water.
The blankets last forever.
I use the Rambo wash or Nikwax. Do you use Johnson’s Baby shampoo? How much? Doesn’t that leave soap? \
My mare gets a sort of sticky greasy feel to her blankets and shoulder guards despite regular grooming- not sure what it is, never had it with other horses. She wears a stable blanket at various weights according to temperature with a light or medium weight waterproof turnout on top when she goes out. I wash the stable sheet/blanket every couple of weeks otherwise it gets gross with body grease and pee/poop from lying down. Turnouts get washed and rewaterproofed in the spring. I do have extras for the lightweight turnout and rain sheets in case they get sodden and muddy but the heavier weight turnouts don’t get wet, just snowy.
My mare has a hog fuel run-out paddock, poops outside, and sleeps in her stall. So there is no real mud, and her blankets don’t get really dirty. But they do get very wet with the rain (PNW) and need to be switched out to dry. The air is so humid here that, at under 10 C/50 F, the blankets will just not dry at all. One of the barns at our facility has heated blanket room, which is just amazing. The blankets will dry in a couple of hours there. But only the people in that particular barn building are allowed to use it 
So I take my wet turnout blanket home and dry it in the front hall of my condo. It makes the whole place smell awful. One blanket in particular (the oldest one) just holds a wet dog smell.
I have two turnout blankets in rotation, and a third that is a bit heavy for our climate, in back-up. Last winter I didn’t really use them at all; this winter, we had six weeks of snow and ice, below freezing. So far I have washed them one at a time over the summer in my in-suite washer on cold, dried them on the deck, and sprayed with a silicon waterproofer. Maybe this summer I will try to sneak into the big machine at the laundromat, or even taken them to the wash service.
I can’t see washing them during the winter because the blanket wash services have a fairly long turnaround time, I think? and I would have nowhere to dry them at home, if I washed them myself.
I’m the opposite of you…I almost never wash them.
I wait until they are dry, and then I just brush the dried mud off with a brush, fold, and hang back up for the next use.
I don’t bother doing anything to them while they are on the horse and in use. If she rolls in the mud with her sheet on and then it rains for a week, well, it stays gross for the week. Once she doesn’t need to wear it anymore, I pull it off, let it dry, and brush the dried junk off.
If the insides of the blanket get real dirty, I might take it to the laundromat. But this doesn’t happen often.
