"Mary Fisher" wrote
I've taken to picking up deiscarded pop bottles in the street (we don't
drink it). After a thorough washing I cut off the bottom, unscrew the top
and bury it, top down, into the ground a few inches from the vegetables'
stems.

This also seems to work a treat in hanging baskets - tried it for the first
time this year, and the baskets managed to survive us going away for half
term week despite the heat (which seems a long time ago now!). Normally we
come back to a basket full of shrivelled sticks...

Martin