hedging

last year or the year before I posted about needing a fast growing hedge/barrier to keep the general public off one side of my plot where there is a path as my allotment site it open to the public.

2 years running I have grown fartachokes, about 20 plants of them. They have provided a lovely hedge thick, quick growing barrier, the plants dont mind being cut to 4 foot and the stems thinned out.
The disadvantages are I really cant eat this many or give them away! currently I've still got 6 plants in the ground and am feeding someones pigs with them.
Any plants grown near them dont seem to do too well, maybe its because they suck all the water up and shade a little. This means the ends of my rows dont get a good crop.

This year I want to try something new.
Rasberries would be great but I dont have enough plants, the plants are expensive, take a while to establish/become a thick barrier and the fruit would get picked.
I have really run out of ideas for fast growing tall veggies, any bright ideas?
If not I may have to resort to flowers....was thinking cosmos

I agree with Lardman or if you put up postS and wire and grow peas, beans and squashes. 

It would be easy to step over a row of cosmos, they're quite an airy plant.
I'd put up a row of canes, with a few beans/ tall peas/sweet peas to grow up them - Does it matter if the beans/peas get eaten - if it keeps people off your plot? After all you're giving away the artichokes at the moment?

Any that you do get to eat from your side will be a bonus

if your planning to move plots at the end of the year could you put raspberries in pots and sink them into the ground.

at least you will have healthier more established plants to take to your next plot

Phacelia - what do you think?