Though I've been checking the greenhouse regularly, I haven't thought
about going into the garden shed until today when I found every drop
of anything liquid frozen solid (glyphosate, compost wetting agent,
the lot). Some 5-litre containers of plant and lawn food that I bought
in a late season sale ready for next year were also solid and both of
those containers had split. they're now inside other containers so I
can hopefully recover the contents when they thaw out.

Moral - might be worth checking any containers of liquids you have to
make sure they're not frozen/broken and, maybe, put them onto trays or
something so there's no chance of them leaking where you don't want
them to.

I'm taking the approach of leaving mine in the cold to thaw gradually
when things warm up rather than bringing them suddenly into a warmer
climate and risking further container cracks.

Jake