The copious rainfall of the last few months and the arrival of the warmer, more spring-like, weather has boosted lots of tender, new plant growth and slugs and snails are seriously busy taking advantage of all that lush greenery.
Great for the snails but a tragedy if you've been watching and waiting for your hostas / lilies / carnations etc. to send up burgeoning new shoots only to find that overnight they've been ravaged by these voracious mollusks.
It's worth checking every pot on a daily basis, lifting it up and inspecting the base to see if there is anything hiding in the drainage holes or under the pot rim. Move pots away from overhanging plants that may also be harbouring the pests; irises are the worst, they seem be a favourite place for snails to hide.
Removing the top few centimetres of soil and replacing with fresh potting compost can also help as snails and slugs lay their eggs in the top few centimetres. It will also give your potted plants a boost.
Use chemical slug pellets only as a last resort.