Have they been potted up in good soil or are they still in seed starting mix? I like to start my peppers a little earlier than tomatoes they seem to take off slow. I would pot them up in good soil and let them get a little bigger before putting them in the ground.

I'm having the same problem with tomatoes. I talked with a lady yesterday who previously had that problem. She said that a warming pad makes all the difference in the world. She ordered hers online for about $30. You just put it underneath the pots and it raises the soil temperature so that the plants will shoot on up. I will definitely be investing in one of those next time around!

I agree with both ladybug & dlhl. Make sure they are in a good potting mix and also that they get plenty of sunlight and warmth. I have continually moved mine inside during night time hours the last few weeks (especially last night) so they can stay somewhat warm. I'm achin' for some summer heat to get all my different peppers growing! =)