For starters I NEVER mix my sweaters in a regular wash load. My knits always get special attention as with most of my wash loads. It may be a bit more time consuming to wash this way, but it is worth it in the long run because it keeps my sweaters in top shape.
I use a very mild detergent for my knits. If it so happens that I have run out of my cleaner of choice, which is usually Woolite, I use just a drop (no more than a tablespoon) of a regular detergent or in the past when my kids were little I would use a bit of baby shampoo. I have used a specialty wash for sweaters in the past and I really enjoyed the outcome because of the lovely smell, but it was not totally necessary. I do however, from time to time, treat myself to a special wash solution when I am feeling fancy:-)
Washing in cold water is really the key to keeping your sweaters and knits in top shape as well as washing them in the gentle cycle. For the most part, I wash my expensive, fancy sweaters, i.e cashmere, wool, pure cotton, or vintage by hand. I never wring them but squeeze the water out and lay them flat to dry on a drying rack in my tub. For sweaters that are not so delicate, I sometimes fold them over the tub or shower rod, but never hang them on a hanger to dry.
Nowadays most sweaters are made of acrylic and manmade fibers and are machine washable but I still wash them separately and with care which means cold water and gentle cycle mostly on an express timeframe. Even though these pieces are not as expensive or rare, I still make sure I treat them with care because I want to get the most use out of them and they are cute! Nothing is worse than jacking up that cute cheap sweater that you loved to wear all of the time because you didn't take time to care for it! Hey I love a fast fashion piece just as much as anyone else and sometimes it's those garments that need more care than others.
I hope this post helps guide you in caring for your knits this season and those to come. There are many more practices out there and I would like to hear from you. Please share some of your best tips and practices in the comments below. Happy sweater weather!