Rendering garden wall

[Felix]

Hi there,

Ive built a raised flower bed in my garden(L9m X H 0.6m) that I want to render, it's made out of breeze block with a base layer of engineering bricks. Can I get away with just giving it one coat of render, to the depth of the angle beads so about 13mm, or will I have to scratch coat it first and then top coat it? If I can one coat it, is it best to just buy a one coat render, and if I two coat it are the following mixes ok:
1st 5x sand 1x lime 1x cement
2nd 6x sand 1x lime 1x cement

Feel free to correct anything, and add advice, thanks in advance.