Raised bed

Need to make a raised bed because last year i bought fly resistant carrot and planted between 2 rows of garlick , still got fly damage.
Have not got a clue how to go about it or how deep to make it?.
Can anyone please help and advise
Cheers Micky v

 

Hi Micky last summer my DH was laying new slabs and instead of putting old to skip turned them on their side to make me a raised veggie bed ,soil is depth of the slab looks good.

Good luck