For what little I know about vine weevil, you will be better off using something like Bug Clear Vine Weevil Killer if treating the problem in containers as it kills the weevils and gives protection for a few months. I think you will find that nematodes are for treatment in the ground. The nematodes feed on the grubs and then when the vine weevils are eaten the nematodes then die out also.

I'd wait a bit longer to let the soil warm up. The nematodes are a good treatment for the grubs, in pots or the ground. On a night look around the tubs with a torch and pick off any adults you find and then crush/stand on them. The good thing is they can't fly.

Yeah…wait a few weeks. It’s very expensive stuff, you don’t want to waste it. Hopefully the weather will change soon! I had same problem with my sedums last year and it was so annoying watching them suffer while waiting for weather to improve. But once I got the stuff on it worked a treat.

Thanks guys, will hold off for now. Have lost a couple of heucheras unfortunately.

If weed seeds are germinating, the soil temperature is above 5C

Andrew, I seem to recall the advice on the packet was temps need to be at least above 10 for the nematode to work. However, we must be getting that by now I should think.