feeding pansys?

No, though you could, in the spring, about March onwards.

i never have but as bamboo says come spring it will help them to keep going through spring.

The short answer is no! The longer answer is - you shouldn't - because they would then grow TOO lush and soft and wouldn't be able to cope with the harsh conditions of winter. They have plenty growth built in already and only once they have flowered their sox off after winter's worst - trim 'em back a bit and feed 'em a little and with any luck they will give you another show through the spring. Good luck...they usually do well in your neck of the woods!