GOOD GOD! Don't use coins! found that out the hard way! Thought it would look cool to have afew coins in my tank...Whoops, FAIL! That said i was 8 at the time and thought 50 cents was a fair amount of money so having $2 in my tank was like a celebrity using diamonds for substrate.
I just smash them down into the gravel, try and spread the roots around an bit then mound the gravel up on top. If it keeps getting ripped up by a pesky fish (Felix the catfish is normally the culprit) I use a skillfully placed fork prong to keep it in place for a few weeks while it roots in.
In order to give them the best chance i really get the ferts going and of course i have CO2 on my tank to help out. more food they have, the faster they will root up and the more O2 they will make. Gotta love it when you see bubbles of O2 rising up off your plants

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