In article ,
Bertie Doe wrote:
"Dave Hill" wrote in message
...

/The main thing that kills dahlias left in the ground is the wet not so
/much the cold, though in a hard winter that will wipe them out.
/As you say Bob you have to put slug bait out from mid May onwards if
/you have left them in.
/Leaving dahlias tubers in plastic bags will almost certainly lead to
/rot unless they are 100% dry, store them in dry compost, slightly damp
/pearlite or vermiculite or peat.

I've noticed the plants don't seem to grow as tall as when I put them in,
say 5 years ago. I suspect the soil is exhausted, despite getting 3
wheelbarrows of cow manure in December.

Possible, but other likely causes are the poor summers we have had,
or parasite build-up (from nematodes to viruses).

Regards,
Nick.