Blue Slate 20mmBlue Slate 20mm Blue is a rare colour in a garden, so adding blue slate to the landscape can provide a distinctive look to your garden. Slate is perfect for use as mulch around plants in a border or to top off containers, and this blue grey coloured slate would work well in an urban garden or a minimalist design. Blue Slate 20mm looks best when wet, so consider using it near a water feature or pond to maximise the effect. Also available as a 40mm Blue