Why not try a surface rooting ground cover such as ajuga?

I wouldn't really add anything else to the pot as it will compete for water and nutrients. I'd probably mulch it with slate/gravel to stop birds squirrels ferreting in the compost.

Hi Sue, a 2 ltr pot doesn't sound very big to me for a grape vine which is going to be there for probably many years, I think you will eventually need a much larger container, are you going to feed it into your greenhouse, or will it be in the open ?, I think it would be better if you could improve the drainage, and plant it in the ground, or create a raised bed about 18" square, and the same depth, then you wouldn't need to disturb it, Derek.

The vine is a small one Derek and only grows to about 6 feet max. I don't have a greenhouse here but the garden slopes to the south and I thought it was worth a try for my trellis arch. The leaves will be attractive even it it doesn't fruit.I can't drain the area because its a soakaway for the overflow from water butt. I rang the supplier re pot size and that was what he recommended. Its not easy to find anything even quite as big as that but I haven't given up yet. Hadn't thought of a raised bed - decisions decisions...
Thanks Eileen and Andrew. I'll sleep on it!

My new grapevine is in a very large pot, must be at least 40L , I was advised to use a big pot to avoid continually repotting plus the roots need moisture all the time. Mine is a replacement for black Hamburg which fruited very well but the pips were a pain. I now have Autumn Royal which is going to be seedless.

Thanks Barbara - but presumably yours is an indoor variety which will get much bigger than 6 feet?

Hi Sue, all Vitis are hardy, the reason some people grow them into, or in, a greenhouse, is because we don't usually get enough summer heat to ripen the fruit, nothing to do with hardiness, its just that the greenhouse is warmer, later into the summer, to give more time to ripen the grapes, Derek.

That's encouraging Derek - maybe occasionally we will get another super summer. And there will be more chance of grapes than there would be on a clematis... Do they need direct sun or just warmth? This one won't get direct sun until mid morning.

Barbara, on second thoughts I wonder if 2l was a typo for 20 l - that would make a lot more sense wouldn't it?

Hi Sue, sun from mid morning should be fine, they need both but the heat is more important, to ripen the grapes.
Yes I wondered if the 2l was a typo, does seem very small, I think a 20l would be more appropriate, good luck with it, I hope we do get more summers like last year, it certainly hasn't been a good summer this year, I think we have had more wet days than dry every month since May, and we're still getting them, Derek.

I'm sure you're right about the misprint Derek. Anyway I've ordered the vine now and at least to begin with will start by potting it on as necessary. When it gets bigger I'll get it a big pot.
We actually had a reasonably good summer eventually, but it's more than made up for it this autumn...makes me glad we live on a hill...

Hi Sue, yes I think that's the way to go, I agree about living on a hill, much more sensible than living on a flood plain, Derek.