There are 19 13-letter words that start with 'pla'.
Note: These 19 13-letter words that start with 'pla' are found from the USA & Canada version of the tournament Scrabble word list.
Also see words start with plan, plas, plat, play, plac, plai, plag, plau, plaf, plaq, plaz.
4-letter words start with 'pla' (3)