Answer: Generally when seedlings stop growing it's because they are not getting the light, water and/or food they require. Even though you have yours in a window with good light, the light probably isn't adequate for your plants and they need to go outdoors to get the full spectrum of light waves the sun can provide. This is true even for plants that grow best in shade; as long as the sun's rays can bounce off other objects in the garden, the plants will be happy in the shade. So, take your seedlings outdoors and they should perk up.
Best wishes with your plants!
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