Scrunched up pots, agreed - and I fill in the gaps with crumpled up newspaper. When I use very big pots, filling with new compost is expensive and not necessary. I use the pots/newspaper method and then add old compost to at least half-way up. Works every time and I have some great summer displays. If I am potting up small pots, I just cover the hole in the bottom with pebble(s) and then some newspaper . Sometimes, just a folded up square of said newspaper … and it's biodegradable.
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