No fines concrete mix ratio 6 : 1 . 6 x crushed blue metal 1 x Portland cement No fines concrete will allow water to pass through but still have a compressive strength of around MPa to about 14 MPa depending on the ratio chosen
Make cement cloth planters. Approximately a water/cement ratio. Add drainage holes in the planter before it completely hardens to prevent cracking. You may also want to apply a couple coats of cement sealer after the planter is dry.