I know it seems that we are getting hung up on the name rather than yje issue but, to me anyway, both of those names miss the point.
We are trying to get MORE plots. Allotments for vegetables seems to imply that we are protesting other things happening to or growing on allotments and crops for plots implies some sort of farming. I appreciate the 2nd one is punchier though.
What about reusing the old "Digging for Victory" which everyone associates with growing food. It shows fighting spirit, determination and growth.
Or "Allotments for your Area", boring but sums it up.
Or "Health not Housing" (ooh political!). Could have an under slogan saying green spaces for growing or something.
Or "Growing Green in your Area"
Or "Outside spaces to feed our faces" - ooh this is the best one yet!
Ok, my ideas aren't great but there are loads of people on here that are good at this sort of thing. I'm sure someone can come up with a really catchy slogan.