Sacha wrote:
Old compost bags are useful for this, too. Used whole they can cover
plants in pots; slit up the sides, they can cover plants in the
ground. We sell our empty ones for a charitable donation of 50p and
I'd suggest anyone and everyone could ask local nurseries if they
would do the same. People also buy them to dispose of garden rubbish
and so forth. They're so strong and sturdy that it seems a shame not
to re-use them where possible.

Grrr, don't let Nick see that!
We have a pile of up-to-4-years-old compost/bark/etc bags tucked behind the
bike shed in a "we will use them one day" fashion, and I'd /almost/
convinced him to throw them out!