Dry Packing lime mortar

Hi, can anyone tell me if dry packing lime mortar (3:1 mix of plastering sand: Lime) is any good or does it need to be wet to start. I need to go round the edge of a patio where it meets the wall and is quite thin. Thanks

 

Just along one edge where it meets the wall, to wick away moisture, the wall is damp. The rest of the patio im using standard. I like lime mortar but have always used it wet before.