Posted: 31/01/2016 at 10:50
Mags.....dig out the soil there and place on a board or sheet of plastic and search through it for small cream coloured,,brown snouted, curved grubs. Squash them or leave them exposed for the birds.
For other polyanthus use Provado vine weevil killer if you want to save them. You can use nematodes in mid spring but by then you will have lost your plants