Soil mix

Hey bro you can easily take more and i would put it on top not bottom of the plant , 11 Liter pot i would take up to 50-75 gram , because it is organic and as it dissolves incredibly slowly, if you have it as a liquid or you can dissolve into water , i would add start it 2 weeks before flowering stage ( (organic fertilizer without running the risk of over-fertilization) Gernerally speaking Use up to 50ml or g per 5L of water when watering every 15 days. Use up to 100ml or g per 15L of soil, mixed in the top layer of soil so that it dissolves slowly when watered. i hope i did anwer your Q, Have fun

If the palm ash is in the bottom then the roots will have to be developed to have access to it. It can't be a bad thing , palm ash is a good stuff for flowering if I remember well it's full of potassium ( K ) and have some phosphorus ( P ) too so it's more a floweing nuts