hi merme,
i don't know much about prayer plants(although i think they are gorgeous) but i think they are ready to go. i know that some plants if left rooted in water too long have trouble adapting to the new soil medium. hopefully someone else will come along and verify. good luck! makes me want to get one.

I think my thumb may be turning green!
I have a Prayer plant clipping that I stuck staight in the dirt four weeks ago.
It did well for two weeks and then started to curl up...thought it was a gonner!I just gave it a little water every day for the first two weeks, then every two days since.
Threw open the curtains this morning and what do you know?It has spread out again and is a nice darkish green with beautiful spots!!!
I've tried this way of planting Prayer plants twice before and they both died.Who knows? Maybe this one will too.
I'll keep you posted

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Work hard. Play hard. Be HONEST !!!