Chilli plants

apocalipzs

So I have some store bought plants and some I started from seed (various varieties). They all live in a green house.

The store bought plants are just beginning to produce chillies and the ones I started from seed range anywhere from a foot high just beginning to produce flowers right down to about 4 inches high.

So the problem I'm having is that the smaller ones have just stopped growing. They're in the same size pot as the store bought which is a 14 litre pot. In the past month they haven't grown. They remain at about 4 inches high. They were transplanted about 2 weeks ago from 15cm pots as I was thinking maybe they're constricted for space to grow. But still no growth.

They're all watered the exact same way. All kept in the greenhouse. All use the same compost - growise multi purpose.

How can I get the smaller ones to grow again? And why is there such a difference between the size of the chilli I started from seed? As an example I have 2 solero chilli plants growing. One is about a good high and the other is about 5 or 6 inches high. Why such a difference between them if they're looked after the same way?