Swiss Mint - Boom and Bust Cycle

My swiss mint is now a year old!  But it's not any bigger.  In fact, it's now smaller.  Let me explain.  Initially the mint grew really well.  Look how big the leaves were.  I even managed to prune it several times and grow new plants from cuttings.  I think most of those died months later.  The mother plant survived though, but barely.   

I'm not really sure why but the stems became spindly.  The plant started losing it's leaves and the new leaves that grew were small and a little rusty.  Still the plant survived.   Although, it's been sunny the past two months, the swiss mint still didn't recover completely.   So I decided to change the soil completely.  I figured maybe that would help. 

Since I had some extra vermicompost left from my various bins, I replaced the soil with vermicompost.  A few weeks later, my swiss mint looks small but well on its way to recovery.  Once again the stems are fat and the leaves are big.  I even have an accidental melon growing in the middle.  I think this is actually the most dramatic impact of vermicompost that I've seen among the many times I've used themf for my plants. Will the swiss mint recover for good or is it just teasing me?  We'll see in a couple of months.

By the way, my newly recovered chocolate mint is dying again.  I'll talk about that next time.

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