Preparing a cacti/arid bed
Here in the southeast UK I will be constructing an arid bed this year, for some hardy cacti/succulents. It is in full sun and my main question is how to best prepare the soil? I have cleared all old plants/weeds and intend to improve the soil drainage, weed fabric on top and then obviously plant of gravel/rocks. My main question is how do I go about constructing it in terms of getting the optimum drainage, both below and above the weed fabric?