When will my Maine Coon kitten develop her full coat and neck ruff?

The 'experts' advise that Maine Coons develop slowly. You will see this all over the Internet. They say that a Maine Coon becomes fully developed at about four years of age. To that you have to add the fact that individual cats develop at different rates so there is some fluidity in that four-year guideline.

Young Maine Coon yet to grow his ruff. Photo: Pinterest and in the public domain.

However, it is pretty clear that young Maine Coons, perhaps below two years of age, normally or often have not fully developed their coat. One Maine Coon cat owner, Lisa Smith (on Quora.com), says that her two sibling male Maine Coons started to develop their ruffs after the age of two. One of the brothers had no ruff at all at two years old. She also says that they were getting stockier and heavier boned at two years old. Further, they started to grow what cat breeders call britches a.k.a. pantaloons on their hind legs. So it looks like it isn't just the ruff which can take time to develop.

Janet Turner, also states on the Internet that she has lived with Maine Coons for many years and currently has three Maine Coon companions. She says that it is difficult to answer the question in the title precisely because individuals vary.

Her oldest cat who in 2018 was 13 years old had a ruff that was not particularly typical of the Maine Coon and therefore was not strictly in line with the breed standard. It was a little bit non-descript and less pronounced. Although it definitely existed. Her other cat, also had a rather weak ruff.

The point of her contribution to this discussion is that individual cats do vary and you will see quite wide variations in respect of the classic ruff for which this cat breed is well-known. It depends upon the breeding line of the individual cats. Breeders obviously select foundation cats which they like and they will dictate the appearance characteristics of their offspring and future offspring.

It's probably wise to ask a cat breeder before adopting questions about the appearance characteristics and how they develop. It's another reason why people who adopt purebred cats should see the parents of the kittens before they adopt so you can get some idea of how the kittens will turn out. Adopters should also see the breeders facility and the kittens. This is said to be vital. There appears to be too many purebred cats casually adopted online from a photograph. This is dangerous. 

You live with your cat for 15-20 years. A big chunk of your life. Take your time before adopting and do due diligence.

P.S. Both books that I have on the Maine Coon written by cat show judges and breeders don't mention the slow development of the Maine Coon. The information comes from MC owners and caregivers.