Just put a recycling idea into practice. After the torrents of rain a very large container flooded. After emptying out the sogginess, I found the drainage holes blocked, despite my having put broken crocks over them to keep clear.
I cut holes in 2 places in the rim of plastic seedling pots. Placed the pots upside down over the drainage holes. Put pea shingle around the inverted pots and refilled the container with fresh dry soil etc.
The drainage should work.
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