As everyone seems to be re vamping their tap root beds I have decided to follow suit. I am going down a slightly different road I have dug out one of my raised beds in the new tunnel, then constructed a framework to suspend the barrels 2 feet off the ground the space underneath has been filled with a mix of compost Vermiculite soil and sand which has been sieved and shredded. The barrels were placed on the framework and filled with the same mix with added nutrients Seaweed Meal Calcified Seaweed Powdered Vitax Q4 and a small amount of Dolomite Lime. I decided on this method instead of sand cored out because this is how I grew my Carrots and Parsnips last year and it worked very well, the total depth of compost is now 4 foot 6 inches I intend to place some 6" diameter pipes on top of one of the barrels to gain another few inches. I found that using compost only last year enabled me to get the roots out easier without loosing the ends and also I have loads of cheap compost to fill the barrels (this is purely experimental so please do not try this at home) as they say.