1. Double posting is against the rules, don't do it. This is a message board, not a chat room.
2. There is a breeding sticky right above your thread that is the place to post all breeding related questions.
To answer your question, there are a few chains to breed Leech Seed from Cacnea to Treecko:
Cacnea > Tropius > Treecko
Cacnea > Chikorita > Treecko
Please post breeding questions in the sticky in the future, thanks!
-Answered, closed