In article , JohnWarden.d261758
@gardenbanter.co.uk says...

I'm blessed 10 months of the year with a garden surrounded by lots of
very large, lovely trees. However, for 2 months of the year I'm deluged
with immense quantities of leaves that are dutifully collected and
eventually turned into huge mounds of leaf mould - lovely stuff.

My query relates to the leaves that fall into the beds and borders
(predominantly perennials and shrubs) and form a very nice snug
environment, much like mulching. Clearly, the leaf cover will protect
emerging shoots from frost, provide a habitat for beneficial insects and
toads, plus the mulching effect won't do any harm. However this snug
environment must also be great for slugs and snails - of which we get
plenty!

Does anyone have a definitive answer to whether it is better to leave
fallen leaves in the borders or to clear them all out?

I leave them on. Mulches are the favourite restaurant for blackbirds
and thrushes and other birds ; they spend hours scratching around in it
hunting for creatures that feed on decaying vegetation.

I apply very heavy mulches every year but very rarely see slugs and
snails in the beds... or any plant damage from them.

Janet.