I am often asked “what are the differences between the different types of No Dig beds ?”
To begin with lets explore what the use of the term No dig means
A the one extreme there is the simple process of covering ground with a layer of compost, and here compost referes to homemade garden compost, greenwaste compost, well rotted animal manure and normally for most people these days this will be produced by horses or a mixture of the above
Then we have the no dig approach were we cover the ground with a weed suppressing mulch like cardboard or plastic to kill weeds wait a season or two for weeds to die then remove and plant this is very time intensive
The quicker method is place cardboard layers onto soil and cover this with a layer of compost this is sometimes referred to as sheet mulching or sheet composting and can work really well for potatoes in a NoDig potato bed and salads especially lettuce so are favoured by micro scale salad growers. the cardboard is essential for suppressing weeds but allowing roots to grow through into the soil beneath
Raised beds are as the name suggests are growing beds that are raised or higher than the soil level. this is achieved by either wooden sides which can give a neat very pleasing tidy effect and allowing the beds to be worked form the dividing paths.
In a more informal vegetable garden or allotment by turfs as in ‘Barra’ beds or 
deeper bed using hay or straw bales and these also could use “hotbed’ techniques
These raised beds and be filled with either compost as above or a mixture of compost and soil depending what is available. Raised beds warm up quicker and drain better and can be more intensively cropped,Beans, peas and root vegetables all prefer these conditions
Lasagna beds are simply beds that are made using layers as in a lasagna. These layers can be differentiated from the other two by a greater intricacy of layers and a predetermined focus on varying layers of nitrogen and carbon and can be taylor made for specific vegetables needs
these beds can be as shallow as 4 inches to as deep as 3 feet in the extreme but 4-6 inches can give fantastic growing conditions so then these are raised lasagna beds!
At its simplest you can grow some vegetables varieties in the sheet composted bed and they do ok but the time and effort it takes to prepare more specific growing conditions always is worth the effort
