blue widow grow

hey peeps rite ive been growing for a while now...............I have 4 blue widow plants on the go they are in 10 ltr pots with coco balls at the bottom of the pots and planted in all mix soil............all 4 were started of in pint size pots and transplanted about 2 weeks ago.............the problem im having is the rates they are all growing at...... 1 is 10 inches tall while 1 is 6inches tall the other 2 are about 7 and 8 inches tall.............and i was wondering if any1 could tell me how i can help the others catch up