Shrubs and trees on a slope should be planted vertically rather than at right angles to the slope. I would suggest digging a 'minni terrace', just the size of the planting hole, then allowing natural erosion to finalise the ground surface.

Agree with Bulbaholic. I planted a bush into the slope in my garden and water accumulated underneath it as the soil must be compacted enough to form a slope in the first place, rotting the roots, everything else planted with the slope has been fine.

OK, thanks folks. Will try the mini terrace plan.

Bulbaholic wrote what I was going to - mini terraces are needed to give a flat surface for water & rain to soak into. I'd incorporate some compost, slow release fertilizer and water retaining gel crystals into the soil at the bottom of each planting hole as well. Keeping moisture on a slope is a major problem. I'm surprised by Kildermorie's finding that water accumulated underneath - my experience is the complete opposite, but I'm gardening on a mine waste tip, so it's extremely stony and hence supremely well drained.

i often actualy create a slight crater/indent wear i put bigger shrubs/plants etc so it just holds a bit more water untill its established .