NOT psychadelic but very groovy.
Just had an article in the permaculture newsletter. The editted out bits were that the plastic sandbags were rubbish, weeds and the weather ruined them in 6 months so now other materials have been used to cover the banks and the weeds have died down. The weeds were couch grass and nettle which have herbal usage.
The aim is to fit more into a small space but using the vertical. Its a permaculture method and as well as being more intensive the idea is to conserve water as less is wasted. To describe it to people i have said its a helter skelter of plants.
In this case a round path was dug and filled with old road planings which were spare. The ground plus the soil from the 5m diameter herb spiral was used to fill sandbags. The weeds and soil filled the poly propolene bags and thus nothing was wasted. It was a physically demanding job but the result was a 50 sack bottom layer drawing a concentric spiral. layers were added each time starting back a bit nearer the centre. When each layer was laid we walked them to settle the contents of the sacks, a fun job. The gaps were infilled with spare soil and compost. Then planted up with herbs leaving spaces for the seedings sown in trays, the circle was bare and gleamed white with the bags. That was March 2009. Now in June its looking gret with the flowers just bursting out and the white sacks often covered up. The weeds are all herbs too. Nettle, Couch Grass and Mare's Tail, but i do weed them out if in wrong place.
The corner beds have 1: different mints with a witchhazel 2: chamomile and a gingko tree 3: culinary herbs with a viburnum opulus (cramp bark). the forth corner has the clay oven (see page on this website). there are two seating areas fashioned from willow with a woven willow and hazel fence. Inside the fence is a herbal hedge with lavender, rosemary and bay.
It is fantastic and now provides a workshop area for herbs as well as a pleasant place to chill. Herbs like licorice stagger people as money don't even realise it was a plant.
workshops can be arranged or visits for groups so get in touch.
UPDATE FEB 2011:
I no longer work at the People's Community Garden as I took up a job with Groundwork EAst of England promoting community environmental action. I have tended the herb spiral once and must visit again before Spring is sprung. Last year we recovered the white bags with mipex (black weed suppressant). It instantly tidies up the look of the spiral. I was well chuffed to see a picture of the herb spiral in the recent permculture magazine.