Wash ragi with enough water and soak it overnight.
Next morning drain water from ragi and tie it in a clean, cotton cloth. Let it rest in dark place or within vessel for about 12 hours.
After 12 hours you can see ragi sprouted. Pat dry ragi in shade spreading it on a clean cloth.
Follow above three steps for the grains like wheat, chickpea and green gram. Green gram and chickpea needs less time to sprout. You can keep them tied in cotton cloth just for 4 hours.
Once all sprouted grains are well dried in shade, roast them separately in kadai/pan. Let it cool.
Grind them to fine powder using your mixer grinder. You can grind them in batches adding dry fruits in each batch. ( If you grind dry fruits separately, it will be sticky as nuts ooze out oil.)
Now sieve this powder. Healthy and nutritious multi grain home made baby cereal is now ready.
Store it in a airtight container. It lasts for a month if you give porridge 3 times a day.