I've used old pallet collars, got them free from few shop warehouses.
We have 4 pallet sizes in use, so I have small ones for herbs and europallet size for other stuff. http://www.palletcollars.org.uk/
Stacked 2 and filled the lower one with horse droppings and second with soil.
In the spring they are covered with old windows, as a miniature greenhouse.
Used "timbers mahogany" for treating, that is a solution of 1/3 wood tar, 1/3 linseed oil and 1/3 terpentine. Just mix all together and paint on.
Have had mine for 5 yrs now and not rotting.
We have 4 pallet sizes in use, so I have small ones for herbs and europallet size for other stuff. http://www.palletcollars.org.uk/
Stacked 2 and filled the lower one with horse droppings and second with soil.
In the spring they are covered with old windows, as a miniature greenhouse.
Used "timbers mahogany" for treating, that is a solution of 1/3 wood tar, 1/3 linseed oil and 1/3 terpentine. Just mix all together and paint on.
Have had mine for 5 yrs now and not rotting.