Writing this I thought hummm… which is it, I was sure unkempt was right in this instance but; so I gave in and looked it up in a well known on-line dictionary.
Unkempt is often used to describe untrimmed lawns and hedges, but unkept is equally correct. Unkept is only rarely used to describe people.
Actually the doubt came because Firefox spell check (set for proper English 🙂 ) flags unkept but not unkempt. Never trust a computer !! as I was told by an instructor many years ago “computers are stupid for two reasons: A. they only have two states, either ‘on’ or ‘off’ so anything else confuses them & B. if the computer says ‘no’ blame the programmer or user never the computer”.